Document and Entity Information - USD ($)	12 Months Ended
Document and Entity Information - USD ($)	Dec. 31, 2017	Jan. 31, 2018	Jun. 30, 2017
Entity Information [Line Items]
Document Type	10-K
Amendment Flag	false
Document Period End Date	Dec. 31, 2017
Document Fiscal Year Focus	2017
Document Fiscal Period Focus	FY
Entity Registrant Name	Under Armour, Inc.
Entity Central Index Key	0001336917
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Class A Common Stock
Entity Information [Line Items]
Trading Symbol	UAA
Entity Common Stock, Shares Outstanding		185,279,913
Entity Public Float			$ 4,001,622,620
Class B Convertible Common Stock
Entity Information [Line Items]
Entity Common Stock, Shares Outstanding		34,450,000
Class C Common Stock
Entity Information [Line Items]
Trading Symbol	UA
Entity Common Stock, Shares Outstanding		222,442,673
Entity Public Float			$ 3,838,231,258

Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Current assets
Cash and cash equivalents	$ 312,483	$ 250,470
Accounts receivable, net	609,670	622,685
Inventories	1,158,548	917,491
Prepaid expenses and other current assets	256,978	174,507
Total current assets	2,337,679	1,965,153
Property and equipment, net	885,774	804,211
Goodwill	555,674	563,591
Intangible assets, net	46,995	64,310
Deferred income taxes	82,801	136,862
Other long term assets	97,444	110,204
Total assets	4,006,367	3,644,331
Current liabilities
Revolving credit facility, current	125,000	0
Accounts payable	561,108	409,679
Accrued expenses	296,841	208,750
Current maturities of long term debt	27,000	27,000
Other current liabilities	50,426	40,387
Total current liabilities	1,060,375	685,816
Long term debt, net of current maturities	765,046	790,388
Other long term liabilities	162,304	137,227
Total liabilities	1,987,725	1,613,431
Commitments and contingencies (see Note 6)
Stockholders’ equity
Additional paid-in capital	872,266	823,484
Retained earnings	1,184,441	1,259,414
Accumulated other comprehensive loss	(38,211)	(52,143)
Total stockholders’ equity	2,018,642	2,030,900
Total liabilities and stockholders’ equity	4,006,367	3,644,331
Class A Common Stock
Stockholders’ equity
Common Stock	61	61
Total stockholders’ equity	61
Class B Convertible Common Stock
Stockholders’ equity
Common Stock	11	11
Total stockholders’ equity	11
Class C Common Stock
Stockholders’ equity
Common Stock	74	$ 73
Total stockholders’ equity	$ 74

Consolidated Balance Sheets (Parenthetical) - $ / shares	Dec. 31, 2017	Dec. 31, 2016
Class A Common Stock
Par value per share (USD Per Share)	$ 0.0003	$ 0.0003
Shares authorized (in shares)	400,000,000	400,000,000
Shares issued (in shares)	185,257,423	183,814,911
Shares outstanding (in shares)	185,257,423	183,814,911
Class B Convertible Common Stock
Par value per share (USD Per Share)	$ 0.0003	$ 0.0003
Shares authorized (in shares)	34,450,000	34,450,000
Shares issued (in shares)	34,450,000	34,450,000
Shares outstanding (in shares)	34,450,000	34,450,000
Class C Common Stock
Par value per share (USD Per Share)	$ 0.0003	$ 0.0003
Shares authorized (in shares)	400,000,000	400,000,000
Shares issued (in shares)	222,375,079	220,174,048
Shares outstanding (in shares)	222,375,079	220,174,048

Consolidated Statements of Operations - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Net revenues	$ 4,976,553	$ 4,825,335	$ 3,963,313
Cost of goods sold	2,737,830	2,584,724	2,057,766
Gross profit	2,238,723	2,240,611	1,905,547
Selling, general and administrative expenses	2,086,831	1,823,140	1,497,000
Restructuring and impairment charges	124,049	0	0
Income from operations	27,843	417,471	408,547
Interest expense, net	(34,538)	(26,434)	(14,628)
Other expense, net	(3,614)	(2,755)	(7,234)
Income (loss) before income taxes	(10,309)	388,282	386,685
Income tax expense	37,951	131,303	154,112
Net income (loss)	(48,260)	256,979	232,573
Net income (loss) available to all stockholders	$ (48,260)	$ 197,979	$ 232,573
Class A Common Stock And Class B Convertible Common Stock
Net income available per common share
Basic net income (loss) per share (USD Per Share)	$ (0.11)	$ 0.45	$ 0.54
Diluted net income (loss) per share (USD Per Share)	$ (0.11)	$ 0.45	$ 0.53
Weighted average common shares outstanding
Basic (in shares)	219,254	217,707	215,498
Diluted (in shares)	219,254	221,944	220,868
Class C Common Stock
Adjustment payment to Class C capital stockholders	$ 0	$ 59,000	$ 0
Net income available per common share
Basic net income (loss) per share (USD Per Share)	$ (0.11)	$ 0.72	$ 0.54
Diluted net income (loss) per share (USD Per Share)	$ (0.11)	$ 0.71	$ 0.53
Weighted average common shares outstanding
Basic (in shares)	221,475	218,623	215,498
Diluted (in shares)	221,475	222,904	220,868

Consolidated Statements of Comprehensive Income (Loss) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Statement of Comprehensive Income [Abstract]
Net income (loss)	$ (48,260)	$ 256,979	$ 232,573
Other comprehensive income (loss):
Foreign currency translation adjustment	23,357	(13,798)	(31,816)
Unrealized gain (loss) on cash flow hedge, net of tax of $(5,668), $3,346 and $415 for the years ended December 31, 2017, 2016, and 2015 respectively.	(16,624)	9,084	1,611
Gain (loss) on intra-entity foreign currency transactions	7,199	(2,416)	0
Total other comprehensive income (loss)	13,932	(7,130)	(30,205)
Comprehensive income (loss)	$ (34,328)	$ 249,849	$ 202,368

Consolidated Statements of Stockholders' Equity - USD ($) shares in Thousands, $ in Thousands	Total	Class A Common Stock	Class C Common Stock	Class B Convertible Common Stock	Common Stock Class A Common Stock	Common Stock Class C Common Stock	Common Stock Class B Convertible Common Stock	Additional Paid-in-Capital	Additional Paid-in-Capital Class A Common Stock	Additional Paid-in-Capital Class C Common Stock	Retained Earnings	Retained Earnings Class C Common Stock	Accumulated Other Comprehensive Income (loss)
Beginning balance (shares) at Dec. 31, 2014					177,296	213,896	36,600
Beginning balance at Dec. 31, 2014	$ 1,350,300				$ 59	$ 71	$ 12	$ 508,279			$ 856,687		$ (14,808)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Exercise of stock options (shares)	720				360	360
Exercise of stock options	$ 2,852							2,852
Shares withheld in consideration of employee tax obligations relative to stock-based compensation arrangements (shares)					(172)	(172)
Shares withheld in consideration of employee tax obligations relative to stock-based compensation arrangements	(12,727)										(12,727)
Issuance of Common Stock, net of forfeitures (shares)					1,996
Issuance of Common Stock, net of forfeitures		$ 19,136			$ 1				$ 19,134
Class B Convertible Common Stock converted to Class A Common Stock (shares)					2,150		(2,150)
Class B Convertible Common Stock converted to Class A Common Stock	0				$ 1		$ (1)
Stock-based compensation expense	60,376							60,376
Net excess tax benefits from stock-based compensation arrangements	45,917							45,917
Comprehensive income	202,368										232,573		(30,205)
Ending balance (shares) at Dec. 31, 2015					181,630	216,080	34,450
Ending balance at Dec. 31, 2015	$ 1,668,222				$ 61	$ 72	$ 11	636,558			1,076,533		(45,013)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Exercise of stock options (shares)	1,763				792	971
Exercise of stock options	$ 6,203							6,203
Shares withheld in consideration of employee tax obligations relative to stock-based compensation arrangements (shares)					(199)	(276)
Shares withheld in consideration of employee tax obligations relative to stock-based compensation arrangements	(15,098)										(15,098)
Issuance of Common Stock, net of forfeitures (shares)					1,592	1,852
Issuance of Common Stock, net of forfeitures		$ 7,884	$ 25,835			$ 1			$ 7,884	$ 25,834
Issuance of Class C dividend (in shares)						1,547
Issuance of Class C dividend			(2,927)							56,073		$ (59,000)
Stock-based compensation expense	46,149							46,149
Net excess tax benefits from stock-based compensation arrangements	44,783							44,783
Comprehensive income	249,849										256,979		(7,130)
Ending balance (shares) at Dec. 31, 2016					183,815	220,174	34,450
Ending balance at Dec. 31, 2016	2,030,900				$ 61	$ 73	$ 11	823,484			1,259,414		(52,143)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Impact of adoption of accounting standard updates	$ (26,598)							(2,666)			(23,932)
Exercise of stock options (shares)	1,046				609	556
Exercise of stock options	$ 3,664							3,664
Shares withheld in consideration of employee tax obligations relative to stock-based compensation arrangements (shares)					(65)	(78)
Shares withheld in consideration of employee tax obligations relative to stock-based compensation arrangements	(2,781)										(2,781)
Issuance of Common Stock, net of forfeitures (shares)					898	1,723
Issuance of Common Stock, net of forfeitures			$ 7,853			$ 1				$ 7,852
Stock-based compensation expense	39,932							39,932
Comprehensive income	(34,328)										(48,260)		13,932
Ending balance (shares) at Dec. 31, 2017		185,257	222,375	34,450
Ending balance at Dec. 31, 2017	$ 2,018,642	$ 61	$ 74	$ 11				$ 872,266			$ 1,184,441		$ (38,211)

Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Cash flows from operating activities
Net income (loss)	$ (48,260)	$ 256,979	$ 232,573
Adjustments to reconcile net income (loss) to net cash used in operating activities
Depreciation and amortization	173,747	144,770	100,940
Unrealized foreign currency exchange rate loss (gains)	(29,247)	12,627	33,359
Impairment charges	71,378	0	0
Amortization of bond premium	254	0	0
Loss on disposal of property and equipment	2,313	1,580	549
Stock-based compensation	39,932	46,149	60,376
Excess tax benefit (loss) from stock-based compensation arrangements	(75)	44,783	45,917
Deferred income taxes	55,910	(43,004)	(4,426)
Changes in reserves and allowances	108,757	70,188	40,391
Changes in operating assets and liabilities (net of acquisitions):
Accounts receivable	(79,106)	(249,853)	(191,876)
Inventories	(222,391)	(148,055)	(278,524)
Prepaid expenses and other assets	(55,503)	(25,284)	(76,476)
Accounts payable	145,695	202,446	(22,583)
Accrued expenses and other liabilities	109,823	67,754	76,854
Income taxes payable and receivable	(39,164)	(16,712)	(2,533)
Net cash provided by operating activities	234,063	364,368	14,541
Cash flows from investing activities
Purchases of property and equipment	(281,339)	(316,458)	(298,928)
Purchases of property and equipment from related parties	0	(70,288)	0
Purchase of businesses, net of cash acquired	0	0	(539,460)
Purchases of available-for-sale securities	0	(24,230)	(103,144)
Sales of available-for-sale securities	0	30,712	96,610
Purchases of other assets	(1,648)	(875)	(2,553)
Net cash used in investing activities	(282,987)	(381,139)	(847,475)
Cash flows from financing activities
Proceeds from long term debt and revolving credit facility	763,000	1,327,601	650,000
Payments on long term debt and revolving credit facility	(665,000)	(1,170,750)	(265,202)
Employee taxes paid for shares withheld for income taxes	(2,781)	(15,098)	(12,728)
Proceeds from exercise of stock options and other stock issuances	11,540	15,485	10,310
Payments of debt financing costs	0	(6,692)	(947)
Cash dividends paid	0	(2,927)	0
Contingent consideration payments for acquisitions	0	(1,505)
Net cash provided by financing activities	106,759	146,114	381,433
Effect of exchange rate changes on cash and cash equivalents	4,178	(8,725)	(11,822)
Net increase (decrease) in cash and cash equivalents	62,013	120,618	(463,323)
Cash and cash equivalents
Beginning of period	250,470	129,852	593,175
End of period	312,483	250,470	129,852
Change in accrual for property and equipment	10,580	16,973	17,758
Non-cash dividends	0	(56,073)
Property and equipment acquired under build-to-suit leases	0	0	5,631
Cash paid for income taxes	36,921	135,959	99,708
Cash paid for interest, net of capitalized interest	$ 29,750	$ 21,412	$ 11,176

Summary of Significant Accounting Policies	12 Months Ended
Summary of Significant Accounting Policies	Dec. 31, 2017
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	Summary of Significant Accounting Policies Basis of Presentation The accompanying consolidated financial statements include the accounts of Under Armour, Inc. and its wholly owned subsidiaries (the “Company”). All intercompany balances and transactions have been eliminated. The accompanying consolidated financial statements were prepared in accordance with accounting principles generally accepted in the United States of America. On June 3, 2016, the Board of Directors approved the payment of a $59.0 million dividend to the holders of the Company's Class C stock in connection with shareholder litigation related to the creation of the Class C stock. The Company's Board of Directors approved the payment of this dividend in the form of additional shares of Class C stock, with cash in lieu of any fractional shares. This dividend was distributed on June 29, 2016, in the form of 1,470,256 shares of Class C stock and $2.9 million in cash. Cash and Cash Equivalents The Company considers all highly liquid investments with an original maturity of three months or less at date of inception to be cash and cash equivalents. Included in interest expense, net for the years ended December 31, 2017, 2016 and 2015 was interest income of $0.4 million, $0.3 million and $0.2 million, respectively, related to cash and cash equivalents. Concentration of Credit Risk Financial instruments that subject the Company to significant concentration of credit risk consist primarily of accounts receivable. The majority of the Company’s accounts receivable is due from large sporting goods retailers. Credit is extended based on an evaluation of the customer’s financial condition and collateral is not required. The Company's largest customer in North America accounted for 12% and 16% of accounts receivable as of December 31, 2017 and December 31, 2016, respectively. The Company's largest customer accounted for 10% and 12% of net revenues for the years ended December 31, 2016 and 2015, respectively. For the year ended December 31, 2017, no customer accounted for more than 10% of net revenues. Allowance for Doubtful Accounts The Company makes ongoing estimates relating to the collectability of accounts receivable and maintains an allowance for estimated losses resulting from the inability of its customers to make required payments. In determining the amount of the reserve, the Company considers historical levels of credit losses and significant economic developments within the retail environment that could impact the ability of its customers to pay outstanding balances and makes judgments about the creditworthiness of significant customers based on ongoing credit evaluations. Because the Company cannot predict future changes in the financial stability of its customers, actual future losses from uncollectible accounts may differ from estimates. If the financial condition of customers were to deteriorate, resulting in their inability to make payments, a larger reserve might be required. In the event the Company determines a smaller or larger reserve is appropriate, it would record a benefit or charge to selling, general and administrative expense in the period in which such a determination was made. As of December 31, 2017 and 2016, the allowance for doubtful accounts was $19.7 million and $11.3 million, respectively. Inventories Inventories consist primarily of finished goods. Costs of finished goods inventories include all costs incurred to bring inventory to its current condition, including inbound freight, duties and other costs. The Company values its inventory at standard cost which approximates landed cost, using the first-in, first-out method of cost determination. Market value is estimated based upon assumptions made about future demand and retail market conditions. If the Company determines that the estimated market value of its inventory is less than the carrying value of such inventory, it records a charge to cost of goods sold to reflect the lower of cost or market. If actual market conditions are less favorable than those projected by the Company, further adjustments may be required that would increase the cost of goods sold in the period in which such a determination was made. Income Taxes Income taxes are accounted for under the asset and liability method. Deferred income tax assets and liabilities are established for temporary differences between the financial reporting basis and the tax basis of the Company’s assets and liabilities at tax rates expected to be in effect when such assets or liabilities are realized or settled. Deferred income tax assets are reduced by valuation allowances when necessary. Assessing whether deferred tax assets are realizable requires significant judgment. The Company considers all available positive and negative evidence, including historical operating performance and expectations of future operating performance. The ultimate realization of deferred tax assets is often dependent upon future taxable income and therefore can be uncertain. To the extent the Company believes it is more likely than not that all or some portion of the asset will not be realized, valuation allowances are established against the Company’s deferred tax assets, which increase income tax expense in the period when such a determination is made. Income taxes include the largest amount of tax benefit for an uncertain tax position that is more likely than not to be sustained upon audit based on the technical merits of the tax position. Settlements with tax authorities, the expiration of statutes of limitations for particular tax positions, or obtaining new information on particular tax positions may cause a change to the effective tax rate. The Company recognizes accrued interest and penalties related to unrecognized tax benefits in the provision for income taxes on the consolidated statements of income. Property and Equipment Property and equipment are stated at cost, including the cost of internal labor for software customized for internal use, less accumulated depreciation and amortization. Property and equipment is depreciated using the straight-line method over the estimated useful lives of the assets: 3 to 10 years for furniture, office equipment, software and plant equipment and 10 to 35 years for site improvements, buildings and building equipment. Leasehold and tenant improvements are amortized over the shorter of the lease term or the estimated useful lives of the assets. The cost of in-store apparel and footwear fixtures and displays are capitalized, included in furniture, fixtures and displays, and depreciated over 3 years. The Company periodically reviews assets’ estimated useful lives based upon actual experience and expected future utilization. A change in useful life is treated as a change in accounting estimate and is applied prospectively. The Company capitalizes the cost of interest for long term property and equipment projects based on the Company’s weighted average borrowing rates in place while the projects are in progress. Capitalized interest was $2.1 million and $1.8 million as of December 31, 2017 and 2016, respectively. Upon retirement or disposition of property and equipment, the cost and accumulated depreciation are removed from the accounts and any resulting gain or loss is reflected in selling, general and administrative expenses for that period. Major additions and betterments are capitalized to the asset accounts while maintenance and repairs, which do not improve or extend the lives of assets, are expensed as incurred. As a part of the Company's 2017 restructuring plan, the Company abandoned the use of several assets included within Property and Equipment, resulting in an impairment charge of $30.7 million, reducing the carrying value of these assets to their estimated fair values. Goodwill, Intangible Assets and Long-Lived Assets Goodwill and intangible assets are recorded at their estimated fair values at the date of acquisition and are allocated to the reporting units that are expected to receive the related benefits. Goodwill and indefinite lived intangible assets are not amortized and are required to be tested for impairment at least annually or sooner whenever events or changes in circumstances indicate that the assets may be impaired. In conducting an annual impairment test, the Company first reviews qualitative factors to determine whether it is more likely than not that the fair value of the reporting unit is less than its carrying amount. If factors indicate that is the case, the Company performs the goodwill impairment test. The Company compares the fair value of the reporting unit with its carrying amount. The Company calculates fair value using the discounted cash flows model, which indicates the fair value of the reporting unit based on the present value of the cash flows that the Company expects the reporting unit to generate in the future. The Company's significant estimates in the discounted cash flows model include: the Company's weighted average cost of capital, long-term rate of growth and profitability of the reporting unit’s business, and working capital effects. If the carrying amount exceeds its fair value, goodwill is impaired to the extent that the carrying value exceeds the fair value of the reporting unit. During the third quarter of 2017, the Company made the strategic decision to not pursue certain planned future revenue streams in its Connected Fitness business in connection with the 2017 Restructuring Plan. The Company determined sufficient indication existed to trigger the performance of an interim impairment for the Company’s Connected Fitness reporting unit resulting in goodwill impairment of $28.6 million, which represents all goodwill allocated to this reporting unit. The Company performs its annual impairment tests in the fourth quarter of each fiscal year. As of December 31, 2017, no impairment of goodwill was identified and the fair value of each reporting unit substantially exceeded its carrying value. The Company continually evaluates whether events and circumstances have occurred that indicate the remaining estimated useful life of long-lived assets may warrant revision or that the remaining balance may not be recoverable. These factors may include a significant deterioration of operating results, changes in business plans, or changes in anticipated cash flows. When factors indicate that an asset should be evaluated for possible impairment, the Company reviews long-lived assets to assess recoverability from future operations using undiscounted cash flows. If future undiscounted cash flows are less than the carrying value, an impairment is recognized in earnings to the extent that the carrying value exceeds fair value. In connection with the Company's 2017 Restructuring Plan, strategic decisions were made during the third quarter in 2017 to abandon the use of certain intangible assets in the Company's Connected Fitness reporting unit. These intangible assets included technology and brand names, resulting in total intangible asset impairment charges of $12.1 million Accrued Expenses At December 31, 2017, accrued expenses primarily included $92.7 million and $47.0 million of accrued compensation and benefits and marketing expenses, respectively. At December 31, 2016, accrued expenses primarily included $60.8 million and $24.7 million of accrued compensation and benefits and marketing expenses, respectively. Foreign Currency Translation and Transactions The functional currency for each of the Company’s wholly owned foreign subsidiaries is generally the applicable local currency. The translation of foreign currencies into U.S. dollars is performed for assets and liabilities using current foreign currency exchange rates in effect at the balance sheet date and for revenue and expense accounts using average foreign currency exchange rates during the period. Capital accounts are translated at historical foreign currency exchange rates. Translation gains and losses are included in stockholders’ equity as a component of accumulated other comprehensive income. Adjustments that arise from foreign currency exchange rate changes on transactions, primarily driven by intercompany transactions, denominated in a currency other than the functional currency are included in other expense, net on the consolidated statements of income. Derivatives and Hedging Activities The Company uses derivative financial instruments in the form of foreign currency and interest rate swap contracts to minimize the risk associated with foreign currency exchange rate and interest rate fluctuations. The Company accounts for derivative financial instruments pursuant to applicable accounting guidance. This guidance establishes accounting and reporting standards for derivative financial instruments and requires all derivatives to be recognized as either assets or liabilities on the balance sheet and to be measured at fair value. Unrealized derivative gain positions are recorded as other current assets or other long term assets, and unrealized derivative loss positions are recorded as other current liabilities or other long term liabilities, depending on the derivative financial instrument’s maturity date. Currently, the majority of the Company’s foreign currency contracts are not designated as cash flow hedges, and accordingly, changes in their fair value are included in other expense, net on the consolidated statements of income. During 2014, the Company began entering into foreign currency contracts designated as cash flow hedges, and consequently, changes in fair value, excluding any ineffective portion, are recorded in other comprehensive income until net income is affected by the variability in cash flows of the hedged transaction. The effective portion is generally released to net income after the maturity of the related derivative and is classified in the same manner as the underlying exposure. Additionally, the Company has designated its interest rate swap contract as a cash flow hedge and accordingly, the effective portion of changes in fair value are recorded in other comprehensive income and reclassified into interest expense over the life of the underlying debt obligation. The ineffective portion, if any, is recognized in current period earnings. The Company does not enter into derivative financial instruments for speculative or trading purposes. Revenue Recognition The Company recognizes revenue pursuant to applicable accounting standards. Net revenues consist of both net sales and license and other revenues. Net sales are recognized upon transfer of ownership, including passage of title to the customer and transfer of risk of loss related to those goods. Transfer of title and risk of loss is based upon shipment under free on board shipping point for most goods or upon receipt by the customer depending on the country of the sale and the agreement with the customer. In some instances, transfer of title and risk of loss takes place at the point of sale, for example, at the Company’s brand and factory house stores. The Company may also ship product directly from its supplier to the customer and recognize revenue when the product is delivered to and accepted by the customer. License and other revenues are primarily recognized based upon shipment of licensed products sold by the Company’s licensees. Sales taxes imposed on the Company’s revenues from product sales are presented on a net basis on the consolidated statements of income and therefore do not impact net revenues or costs of goods sold. The Company records reductions to revenue for estimated customer returns, allowances, markdowns and discounts. The Company bases its estimates on historical rates of customer returns and allowances as well as the specific identification of outstanding returns, markdowns and allowances that have not yet been received by the Company. The actual amount of customer returns and allowances, which is inherently uncertain, may differ from the Company’s estimates. If the Company determines that actual or expected returns or allowances are significantly higher or lower than the reserves it established, it would record a reduction or increase, as appropriate, to net sales in the period in which it makes such a determination. Provisions for customer specific discounts are based on contractual obligations with certain major customers. Reserves for returns, allowances, markdowns and discounts are recorded as an offset to accounts receivable as settlements are made through offsets to outstanding customer invoices. As of December 31, 2017 and 2016, there were $246.6 million and $146.2 million, respectively, in reserves for customer returns, allowances, markdowns and discounts. Advertising Costs Advertising costs are charged to selling, general and administrative expenses. Advertising production costs are expensed the first time an advertisement related to such production costs is run. Media (television, print and radio) placement costs are expensed in the month during which the advertisement appears, and costs related to event sponsorships are expensed when the event occurs. In addition, advertising costs include sponsorship expenses. Accounting for sponsorship payments is based upon specific contract provisions and the payments are generally expensed uniformly over the term of the contract after recording expense related to specific performance incentives once they are deemed probable. Advertising expense, including amortization of in-store marketing fixtures and displays, was $565.1 million, $477.5 million and $417.8 million for the years ended December 31, 2017, 2016 and 2015, respectively. At December 31, 2017 and 2016, prepaid advertising costs were $41.2 million and $32.0 million, respectively. Shipping and Handling Costs The Company charges certain customers shipping and handling fees. These fees are recorded in net revenues. The Company includes the majority of outbound handling costs as a component of selling, general and administrative expenses. Outbound handling costs include costs associated with preparing goods to ship to customers and certain costs to operate the Company’s distribution facilities. These costs, included within selling, general and administrative expenses, were $101.5 million, $89.9 million and $63.7 million for the years ended December 31, 2017, 2016 and 2015, respectively. The Company includes outbound freight costs associated with shipping goods to customers as a component of cost of goods sold. Minority Investment The Company holds a minority investment in Dome Corporation (“Dome”), the Company’s Japanese licensee. The Company invested ¥1,140.0 million, or $15.5 million, in exchange for 19.5% common stock ownership in Dome. As of December 31, 2017 and 2016, the carrying value of the Company’s investment was $12.7 million and $11.7 million, respectively, and was included in other long term assets on the consolidated balance sheets. The investment is subject to foreign currency translation rate fluctuations as it is held by the Company’s European subsidiary. The Company accounts for its investment in Dome under the cost method given that it does not have the ability to exercise significant influence. Additionally, the Company concluded that no event or change in circumstances occurred during the year ended December 31, 2017 that may have a significant adverse effect on the fair value of the investment. Earnings per Share Basic earnings per common share is computed by dividing net income available to common stockholders for the period by the weighted average number of common shares outstanding during the period. Any stock-based compensation awards that are determined to be participating securities, which are stock-based compensation awards that entitle the holders to receive dividends prior to vesting, are included in the calculation of basic earnings per share using the two class method. Diluted earnings per common share is computed by dividing net income available to common stockholders for the period by the diluted weighted average common shares outstanding during the period. Diluted earnings per share reflects the potential dilution from common shares issuable through stock options, warrants, restricted stock units and other equity awards. Refer to Note 11 for further discussion of earnings per share. Stock-Based Compensation The Company accounts for stock-based compensation in accordance with accounting guidance that requires all stock-based compensation awards granted to employees and directors to be measured at fair value and recognized as an expense in the financial statements. In addition, this guidance requires that excess tax benefits related to stock-based compensation awards be reflected as operating cash flows. The Company uses the Black-Scholes option-pricing model to estimate the fair market value of stock-based compensation awards. The Company uses the “simplified method” to estimate the expected life of options, as permitted by accounting guidance. The “simplified method” calculates the expected life of a stock option equal to the time from grant to the midpoint between the vesting date and contractual term, taking into account all vesting tranches. The risk free interest rate is based on the yield for the U.S. Treasury bill with a maturity equal to the expected life of the stock option. Expected volatility is based on the Company's historical average. Compensation expense is recognized net of forfeitures on a straight-line basis over the total vesting period, which is the implied requisite service period. Compensation expense for performance-based awards is recorded over the implied requisite service period when achievement of the performance target is deemed probable. The Company issues new shares of Class A Common Stock and Class C Common Stock upon exercise of stock options, grant of restricted stock or share unit conversion. Refer to Note 12 for further details on stock-based compensation. Management Estimates The preparation of financial statements in conformity with accounting principles generally accepted in the United States of America requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the consolidated financial statements and the reported amounts of revenues and expenses during the reporting period. Actual results could differ from these estimates. Fair Value of Financial Instruments The carrying amounts shown for the Company’s cash and cash equivalents, accounts receivable and accounts payable approximate fair value because of the short term maturity of those instruments. The fair value of the Company's Senior Notes was $526.3 million and $568.1 million as of December 31, 2017 and 2016, respectively. The fair value of the Company's other long term debt approximates its carrying value based on the variable nature of interest rates and current market rates available to the Company. The fair value of foreign currency contracts is based on the net difference between the U.S. dollars to be received or paid at the contracts’ settlement date and the U.S. dollar value of the foreign currency to be sold or purchased at the current exchange rate. The fair value of the interest rate swap contract is based on the net difference between the fixed interest to be paid and variable interest to be received over the term of the contract based on current market rates. Recently Issued Accounting Standards In May 2014, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update ("ASU") 2014-09, which supersedes the most current revenue recognition requirements. This ASU requires entities to recognize revenue in a way that depicts the transfer of goods or services to customers in an amount that reflects the consideration which the entity expects to be entitled to in exchange for those goods or services. This ASU will be effective for annual and interim periods beginning after December 15, 2017, with early adoption for annual and interim periods beginning after December 15, 2016 permitted. The Company’s initial assessment of the guidance in this ASU has identified wholesale customer support costs, direct to consumer incentive programs and customer related returns as transactions potentially affected by this guidance. On the Consolidated Balance Sheet, reserves for returns, allowances, discounts and markdowns will be included as other current liabilities rather than accounts receivable, net and the value of inventory associated with reserves for sales returns will be included within prepaid expenses and other current assets. While the Company has not completed its evaluation, it expects the impact of the adoption of this ASU would primarily change presentation within its consolidated financial statements but is currently not expected to have a material effect on income from operations. The Company will adopt the guidance in this new ASU effective January 1, 2018, and plans to use the modified retrospective transition approach, which would result in an adjustment to retained earnings for the cumulative effect, if any, of applying this guidance to contracts in effect as of the adoption date. Under this approach, the Company would not restate the prior financial statements presented. The guidance in this ASU requires the Company to provide additional disclosures of the amount by which each financial statement line item is affected in the current reporting period during 2018 as compared to the guidance that was in effect before the change, and an explanation of the reasons for significant changes, if any. In January of 2016, the FASB issued ASU 2016-01 which simplifies the impairment assessment of equity investments. This ASU requires equity investments to be measured at fair value with changes recognized in net income. This ASU eliminates the requirement to disclose the methods and assumptions to estimate fair value for financial instruments, requires the use of the exit price for disclosure purposes, requires the change in liability due to a change in credit risk to be presented in other comprehensive income, requires separate presentation of financial assets and liabilities by measurement category and form of asset (securities and loans) and clarifies the need for a valuation allowance on a deferred tax asset related to available-for-sale securities. The guidance in this ASU becomes effective for fiscal periods beginning January 1, 2018 using a cumulative-effect adjustment to the balance sheet. The guidance related to equity securities without readily determinable fair values (including disclosure requirements) shall be applied prospectively to equity investments that exist as of the date of adoption of this update. The Company does not believe the adoption of this ASU will have a material impact on its consolidated financial statements. In February 2016, the FASB issued ASU 2016-02, which amends the existing guidance for leases and will require recognition of operating leases with lease terms of more than twelve months and all financing leases on the balance sheet. For these leases, companies will record assets for the rights and liabilities for the obligations that are created by the leases. This ASU will require disclosures that provide qualitative and quantitative information for the lease assets and liabilities recorded in the financial statements. This ASU is effective for fiscal years beginning after December 15, 2018. The Company is currently evaluating this ASU to determine the impact of its adoption on its consolidated financial statements. The Company currently anticipates adopting the new standard effective January 1, 2019. The Company has formed a committee and initiated the review process for adoption of this ASU. While the Company is still in the process of completing its analysis on the complete impact this ASU will have on its consolidated financial statements and related disclosures, it expects the ASU to have a material impact on its consolidated balance sheet for recognition of lease-related assets and liabilities. In January 2018, the FASB released guidance on the accounting for tax on the global intangible low-taxed income ("GILTI") provisions of the Tax Act. The GILTI provisions impose a tax on foreign income in excess of a deemed return on tangible assets of foreign corporations. The guidance indicates that either accounting for deferred taxes related to GILTI inclusions or to treat any taxes on GILTI inclusions as period costs are both acceptable methods subject to an accounting policy election. The Company has not yet made an accounting policy election in regards to the GILTI provisions under the Tax Act. The Company will make its GILTI accounting policy election during the one-year measurement period as allowed by the SEC. No amounts have been recorded in the Company's 2017 financial statements for the impact of GILTI provisions. Recently Adopted Accounting Standards In March 2016, the FASB issued ASU 2016-09, which affects all entities that issue share-based payment awards to their employees. The amendments in this ASU cover such areas as the recognition of excess tax benefits and deficiencies, the classification of those excess tax benefits on the statement of cash flows, an accounting policy election for forfeitures and the classification of those taxes paid on the statement of cash flows. The Company adopted the provisions of this ASU on January 1, 2017 on a prospective basis and recorded an excess tax deficiency of $1.3 million as an increase in income tax expense related to share-based compensation for vested awards. Additionally, the Company made a policy election under the provisions of this ASU to account for forfeitures when they occur rather than estimating the number of awards that are expected to vest. As a result of this election, upon adoption of the guidance in this ASU, the Company recorded a $1.9 million cumulative-effect benefit to retained earnings as of the date of adoption. The Company adopted the provisions of this ASU related to changes on the Consolidated Statement of Cash Flows on a retrospective basis. Excess tax benefits and deficiencies have been classified within cash flows from operating activities and employee taxes paid for shares withheld for income taxes have been classified within cash flows from financing activities on the Consolidated Statement of Cash Flows. This resulted in increases of $44.8 million and $45.9 million to cash flows from operating activities for the years ended December 31, 2016 and 2015, respectively. This also resulted in decreases of $15.1 million and $12.7 million to cash flows from financing activities for the year ended December 31, 2015 and 2016, respectively. In October 2016, the FASB issued ASU 2016-16, which requires an entity to recognize the income tax consequences of an intra-entity transfer of an asset, other than inventory, when the transfer occurs. The Company adopted the provisions of this ASU on a modified retrospective basis on January 1, 2017, resulting in a cumulative-effect benefit to retained earnings of $26.0 million as of the date of adoption. In January 2017, the FASB issued ASU 2017-04, which simplifies how an entity is required to test goodwill for impairment by eliminating step two of the test. The Company adopted the provisions of this ASU on July 1, 2017, and recorded an impairment charge of $28.6 million during its interim goodwill impairment test for the Connected Fitness reporting unit.

Restructuring and Impairments

12 Months Ended

Dec. 31, 2017

Restructuring and Related Activities [Abstract]

Restructuring and Impairments

Restructuring and Impairment

A description of significant restructuring and related impairment charges is included below:

2017 Restructuring Plan

On July 27, 2017, the Company’s Board of Directors approved a restructuring plan (the “2017 restructuring plan”) to more closely align its financial resources with the critical priorities of the business. After completion of the 2017 restructuring plan, the Company recognized approximately $100.4 million of pre-tax charges in connection with this restructuring plan. In addition to these charges, the Company also recognized restructuring related goodwill impairment charges of approximately $28.6 million for its Connected Fitness business.

Impairment

As a part of the 2017 restructuring plan, the Company abandoned the use of several assets included within Property and Equipment, resulting in an impairment charge of $30.7 million, reducing the carrying value of these assets to their estimated fair values. Fair value was estimated using an income-approach based on management’s forecast of future cash flows expected to be derived from the assets' use.

Additionally, in connection with the 2017 restructuring plan, strategic decisions were made during the third quarter of 2017 to abandon the use of certain intangible assets in the Company's Connected Fitness reporting unit. These intangible assets included technology and brand names, resulting in total intangible asset impairment charges of $12.1 million, reducing the carrying value of these assets to their estimated fair values. Fair value was estimated using an income-approach based on management’s forecast of future cash flows expected to be derived from the assets use. In addition, the Company also made the strategic decision to not pursue certain other planned future revenue streams in connection with the 2017 restructuring plan.

The Company determined sufficient indication existed to trigger the performance of an interim goodwill impairment for the Company’s Connected Fitness reporting unit. Using updated cash flow projections, the Company calculated the fair value of the Connected Fitness reporting unit based on the discounted cash flows model. The carrying value exceeded the fair value, resulting in an impairment of goodwill. As the excess of the carrying value for the Connected Fitness reporting unit was greater than the goodwill for this reporting unit, all of the goodwill was impaired.

The summary of the costs incurred during the year ended December 31, 2017 in connection with the 2017 restructuring plan are as follows:



	Year Ended December 31,
(In thousands)	2017
Costs recorded in cost of goods sold:
Inventory write-offs (1)	$	5,077
Total costs recorded in cost of goods sold	5,077

Costs recorded in restructuring and impairment charges:
Goodwill impairment	28,647
Property and equipment impairment	30,677
Employee related costs	14,572
Intangible asset impairment	12,054
Contract exit costs	12,029
Other restructuring costs	26,070
Total costs recorded in restructuring and impairment charges	124,049
Total restructuring, impairment and restructuring related costs	$	129,126

(1) This table includes an additional non-cash charge of $5.1 million for the year ended December 31, 2017 associated with the disposition of inventory outside of current liquidation channels in line with the 2017 restructuring plan.

A summary of the activity in the restructuring reserve related to the 2017 Restructuring Plan is as follows:



	Employee Related costs			Contract Exit Costs			Other Restructuring Related Costs
Balance at January 1, 2017	$	—		$	—		$	—
Additions charged to expense	14,572			12,029			13,070
Cash payments charged against reserve	(10,017		)	(9,181		)	(10,070		)
Balance at December 31, 2017	$	4,555		$	2,848		$	3,000

2018 Restructuring Plan

On February 9, 2018, the Company's Board of Directors approved an additional restructuring plan (the "2018 restructuring plan") identifying further opportunities to optimize operations. In conjunction with this plan, approximately $110 to $130 million of pre-tax restructuring and related charges are expected to be incurred during the Company's 2018 fiscal year, including:


•	Up to $105.0 million in cash charges, consisting of up to: $55.0 million in facility and lease terminations and $50.0 million in contract termination and other restructuring charges; and,


•	Up to $25.0 million in non-cash charges comprised of approximately $10.0 million of inventory related charges and approximately $15.0 million of intangibles and other asset related impairments.

Property and Equipment, Net

12 Months Ended

Dec. 31, 2017

Property, Plant and Equipment [Abstract]

Property and Equipment, Net

Property and equipment consisted of the following:



	December 31,
(In thousands)	2017			2016
Leasehold and tenant improvements	$	431,761		$	326,617
Furniture, fixtures and displays	204,926			168,720
Buildings	47,625			47,216
Software	232,660			151,059
Office equipment	98,802			75,196
Plant equipment	144,484			124,140
Land	83,574			83,574
Construction in progress	148,488			204,362
Other	20,438			20,383
Subtotal property and equipment	1,412,758			1,201,267
Accumulated depreciation	(526,984		)	(397,056		)
Property and equipment, net	$	885,774		$	804,211

Construction in progress primarily includes costs incurred for software systems, leasehold improvements and in-store fixtures and displays not yet placed in use.

Depreciation expense related to property and equipment was $164.3 million, $130.7 million and $86.3 million for the years ended December 31, 2017, 2016 and 2015, respectively.

Goodwill and Intangible Assets, Net

12 Months Ended

Dec. 31, 2017

Goodwill and Intangible Assets Disclosure [Abstract]

Goodwill and Intangible Assets, Net

The following table summarizes changes in the carrying amount of the Company’s goodwill by reportable segment as of the periods indicated:



	North America		EMEA		Asia-Pacific		Latin America		Connected Fitness			Total
Balance as of December 31, 2016	$	317,323	$	99,245	$	77,586	$	42,436	$	27,001		$	563,591
Effect of currency translation adjustment	1,132		11,910		3,737		2,305		1,646			20,730
Impairment	—		—		—		—		(28,647		)	(28,647		)
Balance as of December 31, 2017	$	318,455	$	111,155	$	81,323	$	44,741	$	—		$	555,674

The following table summarizes the Company’s intangible assets as of the periods indicated:



		December 31, 2017										December 31, 2016
(In thousands)	Useful Lives from Date of Acquisitions (in years)	Gross Carrying Amount		Accumulated Amortization			Impairment			Net Carrying Amount		Gross Carrying Amount		Accumulated Amortization			Net Carrying Amount
Intangible assets subject to amortization:
User base	10	$	48,561	$	(13,499	)	$	—		$	35,062	$	47,653	$	(8,733	)	$	38,920
Technology	5-7	19,611		(9,524		)	(10,087		)	—		19,612		(8,221		)	11,391
Customer relationships	2-3	9,527		(9,527		)	—			—		9,527		(9,527		)	—
Trade name	4-5	7,653		(5,686		)	(1,967		)	—		7,653		(4,816		)	2,837
Nutrition database	10	4,500		(1,256		)	—			3,244		4,500		(806		)	3,694
Lease-related intangible assets	1-15	3,896		(3,232		)	—			664		3,896		(3,075		)	821
Other	5-10	1,353		(892		)	—			461		1,373		(666		)	707
Total		$	95,101	$	(43,616	)	$	(12,054	)	$	39,431	$	94,214	$	(35,844	)	$	58,370
Indefinite-lived intangible assets										7,564							5,940
Intangible assets, net										$	46,995						$	64,310

Amortization expense, which is included in selling, general and administrative expenses, was $8.2 million, $13.0 million and $13.9 million for the years ended December 31, 2017, 2016 and 2015, respectively. The following is the estimated amortization expense for the Company’s intangible assets as of December 31, 2017:



(In thousands)
2018	$	5,715
2019	5,608
2020	5,536
2021	5,447
2022	5,428
2023 and thereafter	11,697
Amortization expense of intangible assets	$	39,431

- Definition

The entire disclosure for the aggregate amount of goodwill and a description of intangible assets, which may include (a) for amortizable intangible assets (also referred to as finite-lived intangible assets), the carrying amount, the amount of any significant residual value, and the weighted-average amortization period, (b) for intangible assets not subject to amortization (also referred to as indefinite-lived intangible assets), the carrying amount, and (c) the amount of research and development assets acquired and written off in the period, including the line item in the income statement in which the amounts written off are aggregated, if not readily apparent from the income statement. Also discloses (a) for amortizable intangibles assets in total and by major class, the gross carrying amount and accumulated amortization, the total amortization expense for the period, and the estimated aggregate amortization expense for each of the five succeeding fiscal years, (b) for intangible assets not subject to amortization the carrying amount in total and by major class, and (c) for goodwill, in total and for each reportable segment, the changes in the carrying amount of goodwill during the period (including the aggregate amount of goodwill acquired, the aggregate amount of impairment losses recognized, and the amount of goodwill included in the gain (loss) on disposal of a reporting unit). If any part of goodwill has not been allocated to a reportable segment, discloses the unallocated amount and the reasons for not allocating. For each impairment loss recognized related to an intangible asset (excluding goodwill), discloses: (a) a description of the impaired intangible asset and the facts and circumstances leading to the impairment, (b) the amount of the impairment loss and the method for determining fair value, (c) the caption in the income statement or the statement of activities in which the impairment loss is aggregated, and (d) the segment in which the impaired intangible asset is reported. For each goodwill impairment loss recognized, discloses: (a) a description of the facts and circumstances leading to the impairment, (b) the amount of the impairment loss and the method of determining the fair value of the associated reporting unit, and (c) if a recognized impairment loss is an estimate not finalized and the reasons why the estimate is not final. May also disclose the nature and amount of any significant adjustments made to a previous estimate of an impairment loss.

+ References + Details

Credit Facility and Long Term Debt

12 Months Ended

Dec. 31, 2017

Debt Disclosure [Abstract]

Credit Facility and Long Term Debt

Credit Facility and Other Long Term Debt

Credit Facility

The Company is party to a credit agreement that provides revolving commitments for up to $1.25 billion of borrowings, as well as term loan commitments, in each case maturing in January 2021. As of December 31, 2017 the outstanding balance under the revolving credit facility was $125.0 million and $161.3 million of term loan borrowings remained outstanding.

At the Company's request and the lender's consent, revolving and or term loan borrowings may be increased by up to $300.0 million in aggregate, subject to certain conditions as set forth in the credit agreement, as amended. Incremental borrowings are uncommitted and the availability thereof, will depend on market conditions at the time the Company seeks to incur such borrowings.

The borrowings under the revolving credit facility have maturities of less than one year. Up to $50.0 million of the facility may be used for the issuance of letters of credit. There were $4.5 million of letters of credit outstanding as of December 31, 2017.

The credit agreement contains negative covenants that, subject to significant exceptions, limit the ability of the Company and its subsidiaries to, among other things, incur additional indebtedness, make restricted payments, pledge their assets as security, make investments, loans, advances, guarantees and acquisitions, undergo fundamental changes and enter into transactions with affiliates. The Company is also required to maintain a ratio of consolidated EBITDA, as defined in the credit agreement, to consolidated interest expense of not less than 3.50 to 1.00 and is not permitted to allow the ratio of consolidated total indebtedness to consolidated EBITDA to be greater than 3.25 to 1.00 ("consolidated leverage ratio"). As of December 31, 2017, the Company was in compliance with these ratios. In February 2018, the Company amended the credit agreement to amend the definition of consolidated EBITDA, and to provide that the Company's trailing four-quarter consolidated leverage ratio may not exceed 3.75 to 1.00 for the four quarters ended June 30, 2018, and 4.00 to 1.00 for the four quarters ended September 30, 3018. Beginning with the four quarters ended December 31, 2018 and thereafter, the consolidated leverage ratio requirement will return to 3.25 to 1.00. In addition, the credit agreement contains events of default that are customary for a facility of this nature, and includes a cross default provision whereby an event of default under other material indebtedness, as defined in the credit agreement, will be considered an event of default under the credit agreement.

Borrowings under the credit agreement bear interest at a rate per annum equal to, at the Company’s option, either (a) an alternate base rate, or (b) a rate based on the rates applicable for deposits in the interbank market for U.S. Dollars or the applicable currency in which the loans are made (“adjusted LIBOR”), plus in each case an applicable margin. The applicable margin for loans will be adjusted by reference to a grid (the “Pricing Grid”) based on the consolidated leverage ratio and ranges between 1.00% to 1.25% for adjusted LIBOR loans and 0.00% to 0.25% for alternate base rate loans. The weighted average interest rate under the outstanding term loans and revolving credit facility borrowings was 2.2% and 1.6% during the years ended December 31, 2017 and 2016, respectively. The Company pays a commitment fee on the average daily unused amount of the revolving credit facility and certain fees with respect to letters of credit. As of December 31, 2017, the commitment fee was 17.5 basis points. Since inception, the Company incurred and deferred $3.9 million in financing costs in connection with the credit agreement.

3.250% Senior Notes

In June 2016, the Company issued $600.0 million aggregate principal amount of 3.250% senior unsecured notes due June 15, 2026 (the “Notes”). The proceeds were used to pay down amounts outstanding under the revolving credit facility. Interest is payable semi-annually on June 15 and December 15 beginning December 15, 2016. Prior to March 15, 2026 (three months prior to the maturity date of the Notes), the Company may redeem some or all of the Notes at any time or from time to time at a redemption price equal to the greater of 100% of the principal amount of the Notes to be redeemed or a “make-whole” amount applicable to such Notes as described in the indenture governing the Notes, plus accrued and unpaid interest to, but excluding, the redemption date. On or after March 15, 2026 (three months prior to the maturity date of the Notes), the Company may redeem some or all of the Notes at any time or from time to time at a redemption price equal to 100% of the principal amount of the Notes to be redeemed, plus accrued and unpaid interest to, but excluding, the redemption date.

The indenture governing the Notes contains covenants, including limitations that restrict the Company’s ability and the ability of certain of its subsidiaries to create or incur secured indebtedness and enter into sale and leaseback transactions and the Company’s ability to consolidate, merge or transfer all or substantially all of its properties or assets to another person, in each case subject to material exceptions described in the indenture. The Company incurred and deferred $5.3 million in financing costs in connection with the Notes.

Other Long Term Debt

In December 2012, the Company entered into a $50.0 million recourse loan collateralized by the land, buildings and tenant improvements comprising the Company's corporate headquarters. The loan has a seven year term and maturity date of December 2019. The loan bears interest at one month LIBOR plus a margin of 1.50%, and allows for prepayment without penalty. The loan includes covenants and events of default substantially consistent with the Company's credit agreement discussed above. The loan also requires prior approval of the lender for certain matters related to the property, including transfers of any interest in the property. As of December 31, 2017 and 2016, the outstanding balance on the loan was $40.0 million and $42.0 million, respectively. The weighted average interest rate on the loan was 2.5% and 2.0% for the years ended December 31, 2017 and 2016, respectively.

The following are the scheduled maturities of long term debt as of December 31, 2017:



(In thousands)
2018	$	27,000
2019	63,000
2020	25,000
2021	86,250
2022	—
2023 and thereafter	600,000
Total scheduled maturities of long term debt	$	801,250

Current maturities of long term debt	$	27,000

Interest expense, net was $34.5 million, $26.4 million, and $14.6 million for the years ended December 31, 2017, 2016 and 2015, respectively. Interest expense includes the amortization of deferred financing costs, bank fees, capital and built-to-suit lease interest and interest expense under the credit and other long term debt facilities. Amortization of deferred financing costs was $1.3 million, $1.2 million, and $0.8 million for the years ended December 31, 2017, 2016 and 2015, respectively.

The Company monitors the financial health and stability of its lenders under the credit and other long term debt facilities, however during any period of significant instability in the credit markets lenders could be negatively impacted in their ability to perform under these facilities.

Commitments And Contingencies

12 Months Ended

Dec. 31, 2017

Commitments and Contingencies Disclosure [Abstract]

Commitments And Contingencies

Commitments and Contingencies

Obligations Under Operating Leases

The Company leases warehouse space, office facilities, space for its brand and factory house stores and certain equipment under non-cancelable operating leases. The leases expire at various dates through 2033, excluding extensions at the Company’s option, and include provisions for rental adjustments. The table below includes executed lease agreements for brand and factory house stores that the Company did not yet occupy as of December 31, 2017 and does not include contingent rent the Company may incur at its stores based on future sales above a specified minimum or payments made for maintenance, insurance and real estate taxes. The following is a schedule of future minimum lease payments for non-cancelable real property operating leases as of December 31, 2017 as well as significant operating lease agreements entered into during the period after December 31, 2017 through the date of this report:



(In thousands)
2018	140,257
2019	139,304
2020	158,455
2021	147,094
2022	132,312
2023 and thereafter	772,047
Total future minimum lease payments	$	1,489,469

Included in selling, general and administrative expense was rent expense of $141.2 million, $109.0 million and $83.0 million for the years ended December 31, 2017, 2016 and 2015, respectively, under non-cancelable operating lease agreements. Included in these amounts was contingent rent expense of $15.5 million, $13.0 million and $11.0 million for the years ended December 31, 2017, 2016 and 2015, respectively.

Sports Marketing and Other Commitments

Within the normal course of business, the Company enters into contractual commitments in order to promote the Company’s brand and products. These commitments include sponsorship agreements with teams and athletes on the collegiate and professional levels, official supplier agreements, athletic event sponsorships and other marketing commitments. The following is a schedule of the Company’s future minimum payments under its sponsorship and other marketing agreements as of December 31, 2017, as well as significant sponsorship and other marketing agreements entered into during the period after December 31, 2017 through the date of this report:



(In thousands)
2018	150,428
2019	135,165
2020	126,026
2021	121,710
2022	119,783
2023 and thereafter	517,736
Total future minimum sponsorship and other payments	$	1,170,848

The amounts listed above are the minimum compensation obligations and guaranteed royalty fees required to be paid under the Company’s sponsorship and other marketing agreements. The amounts listed above do not include additional performance incentives and product supply obligations provided under certain agreements. It is not possible to determine how much the Company will spend on product supply obligations on an annual basis as contracts generally do not stipulate specific cash amounts to be spent on products. The amount of product provided to the sponsorships depends on many factors including general playing conditions, the number of sporting events in which they participate and the Company’s decisions regarding product and marketing initiatives. In addition, the costs to design, develop, source and purchase the products furnished to the endorsers are incurred over a period of time and are not necessarily tracked separately from similar costs incurred for products sold to customers.

Other

In connection with various contracts and agreements, the Company has agreed to indemnify counterparties against certain third party claims relating to the infringement of intellectual property rights and other items. Generally, such indemnification obligations do not apply in situations in which the counterparties are grossly negligent, engage in willful misconduct, or act in bad faith. Based on the Company’s historical experience and the estimated probability of future loss, the Company has determined that the fair value of such indemnifications is not material to its consolidated financial position or results of operations.

From time to time, the Company is involved in litigation and other proceedings, including matters related to commercial and intellectual property disputes, as well as trade, regulatory and other claims related to its business. Other than as described below, the Company believes that all current proceedings are routine in nature and incidental to the conduct of its business, and that the ultimate resolution of any such proceedings will not have a material adverse effect on its consolidated financial position, results of operations or cash flows.

On March 23, 2017, three separate securities cases previously filed against the Company in the United States District Court for the District of Maryland (the “Court”) were consolidated under the caption In re Under Armour Securities Litigation, Case No. 17-cv-00388-RDB (the “Consolidated Action”). On August 4, 2017, the lead plaintiff in the Consolidated Action, North East Scotland Pension Fund, joined by named plaintiff Bucks County Employees Retirement Fund, filed a consolidated amended complaint (the “Amended Complaint”) against the Company, the Company’s Chief Executive Officer and former Chief Financial Officers, Lawrence Molloy and Brad Dickerson. The Amended Complaint alleges violations of Section 10(b) (and Rule 10b-5) of the Securities Exchange Act of 1934, as amended (the “Exchange Act”) and Section 20(a) control person liability under the Exchange Act against the officers named in the Amended Complaint, claiming that the defendants made material misstatements and omissions regarding, among other things, the Company's growth and consumer demand for certain of the Company's products. The class period identified in the Amended Complaint is September 16, 2015 through January 30, 2017. The Amended Complaint also asserts claims under Sections 11 and 15 of the Securities Act of 1933, as amended (the “Securities Act”), in connection with the Company’s public offering of senior unsecured notes in June 2016. The Securities Act claims are asserted against the Company, the Company’s Chief Executive Officer, Mr. Molloy, the Company’s directors who signed the registration statement pursuant to which the offering was made and the underwriters that participated in the offering. The Amended Complaint alleges that the offering materials utilized in connection with the offering contained false and/or misleading statements and omissions regarding, among other things, the Company’s growth and consumer demand for certain of the Company’s products. On November 9, 2017, the Company and the other defendants filed a motion to dismiss the Amended Complaint, which is still pending with the Court. The Company believes that the claims asserted in the Consolidated Action are without merit and intends to defend the lawsuit vigorously. However, because of the inherent uncertainty as to the outcome of this proceeding, the Company is unable at this time to estimate the possible impact of the outcome of this matter.

Stockholders' Equity	12 Months Ended
Stockholders' Equity	Dec. 31, 2017
Stockholders' Equity Note [Abstract]
Stockholders' Equity	Stockholders’ Equity The Company’s Class A Common Stock and Class B Convertible Common Stock have an authorized number of shares at December 31, 2017 of 400.0 million shares and 34.5 million shares, respectively, and each have a par value of $0.0003 1/3 per share. Holders of Class A Common Stock and Class B Convertible Common Stock have identical rights, including liquidation preferences, except that the holders of Class A Common Stock are entitled to one vote per share and holders of Class B Convertible Common Stock are entitled to 10 votes per share on all matters submitted to a stockholder vote. Class B Convertible Common Stock may only be held by Kevin Plank, the Company’s founder and Chief Executive Officer, or a related party of Mr. Plank, as specified in the Company’s charter. As a result, Mr. Plank has a majority voting control over the Company. Upon the transfer of shares of Class B Convertible Stock to a person other than Mr. Plank or a related party of Mr. Plank, the shares automatically convert into shares of Class A Common Stock on a one-for-one basis. In addition, all of the outstanding shares of Class B Convertible Common Stock will automatically convert into shares of Class A Common Stock on a one-for-one basis upon the death or disability of Mr. Plank or on the record date for any stockholders’ meeting upon which the shares of Class A Common Stock and Class B Convertible Common Stock beneficially owned by Mr. Plank is less than 15% of the total shares of Class A Common Stock and Class B Convertible Common Stock outstanding or upon the other events specified in the Class C Charter. Holders of the Company’s common stock are entitled to receive dividends when and if authorized and declared out of assets legally available for the payment of dividends. In June 2015, the Company's Board of Directors (the “Board”) approved Articles Supplementary to the Company's charter which designated 400.0 million shares of common stock as a new class of common stock, referred to as the Class C common stock, par value $0.0003 1/3 per share. The Articles Supplementary became effective on June 15, 2015. In April 2016, the Company issued shares of Class C common stock as a dividend to the Company's holders of Class A and Class B common stock on a one-for-one basis. The terms of the Class C common stock are substantially identical to those of the Company's Class A common stock, except that the Class C common stock has no voting rights (except in limited circumstances), will automatically convert into Class A common stock under certain circumstances and includes provisions intended to ensure equal treatment of Class C common stock and Class B common stock in certain corporate transactions, such as mergers, consolidations, statutory share exchanges, conversions or negotiated tender offers, and including consideration incidental to these transactions.

Fair Value Measurements

12 Months Ended

Dec. 31, 2017

Fair Value Disclosures [Abstract]

Fair Value Measurements

Fair value is defined as the price that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date (an exit price). The fair value accounting guidance outlines a valuation framework, creates a fair value hierarchy in order to increase the consistency and comparability of fair value measurements and the related disclosures, and prioritizes the inputs used in measuring fair value as follows:



Level 1:	Observable inputs such as quoted prices in active markets;

Level 2:	Inputs, other than quoted prices in active markets, that are observable either directly or indirectly; and

Level 3:	Unobservable inputs for which there is little or no market data, which require the reporting entity to develop its own assumptions.

Financial assets and (liabilities) measured at fair value are set forth in the table below:



	December 31, 2017							December 31, 2016
(In thousands)	Level 1		Level 2			Level 3		Level 1		Level 2			Level 3
Derivative foreign currency contracts (see Note 8)	$	—	$	(6,818	)	$	—	$	—	$	15,238		$	—
Interest rate swap contracts (see Note 8)	—		1,088			—		—		(420		)	—
TOLI policies held by the Rabbi Trust	—		5,756			—		—		4,880			—
Deferred Compensation Plan obligations	—		(7,971		)	—		—		(7,023		)	—

Fair values of the financial assets and liabilities listed above are determined using inputs that use as their basis readily observable market data that are actively quoted and are validated through external sources, including third-party pricing services and brokers. The Company purchases marketable securities that are designated as available-for-sale. The foreign currency contracts represent gains and losses on derivative contracts, which is the net difference between the U.S. dollar value to be received or paid at the contracts’ settlement date and the U.S. dollar value of the foreign currency to be sold or purchased at the current market exchange rate. The interest rate swap contracts represent gains and losses on the derivative contracts, which is the net difference between the fixed interest to be paid and variable interest to be received over the term of the contract based on current market rates. The fair value of the trust owned life insurance (“TOLI”) policies held by the Rabbi Trust is based on the cash-surrender value of the life insurance policies, which are invested primarily in mutual funds and a separately managed fixed income fund. These investments are initially made in the same funds and purchased in substantially the same amounts as the selected investments of participants in the Under Armour, Inc. Deferred Compensation Plan (the “Deferred Compensation Plan”), which represent the underlying liabilities to participants in the Deferred Compensation Plan. Liabilities under the Deferred Compensation Plan are recorded at amounts due to participants, based on the fair value of participants’ selected investments.

As of the fair value of the Company's Senior Notes was $526.3 million and $568.1 million as of December 31, 2017 and 2016, respectively. The carrying value of the Company's other long term debt approximated its fair value as of December 31, 2017 and 2016. The fair value of long-term debt is estimated based upon quoted prices for similar instruments or quoted prices for identical instruments in inactive markets (Level 2).

Provision for Income Taxes

12 Months Ended

Dec. 31, 2017

Income Tax Disclosure [Abstract]

Provision for Income Taxes

On December 22, 2017, the Tax Cuts and Jobs Act (the “Tax Act”) was enacted in the United States. The Tax Act includes a number of changes to existing U.S. tax laws that impact the Company including the reduction of the U.S. corporate income tax rate from 35 percent to 21 percent for tax years beginning after December 31, 2017. The Tax Act also provides for a one-time transition tax on indefinitely reinvested foreign earnings and the acceleration of depreciation for certain assets placed into service after September 27, 2017, as well as prospective change beginning in 2018, including the elimination of certain domestic deductions and credits, capitalization of research and development expenditures, and additional limitations on the deductibility of executive compensation and interest.

The Company recognized the income tax effects of the Tax Act in its 2017 financial statements in accordance with Staff Accounting Bulletin No. 118, which provides SEC staff guidance for the application of ASC Topic 740, Income Taxes, in the reporting period in which the Tax Act was signed into law. As such, the Company’s financial results reflect the income tax effects of the Tax Act for which accounting under ASC Topic 740 is incomplete but a reasonable estimate could be determined. The Company did not identify items for which the income tax effects of the Tax Act have not been completed and a reasonable estimate could not be determined as of December 31, 2017.

The changes to existing U.S. tax laws as a result of the Tax Act, which have the most significant impact on the company’s provision for income taxes as of December 31, 2017 are as follows:

Reduction of the U.S. Corporate Income Tax Rate

The company measures deferred tax assets and liabilities using enacted tax rates that will apply in the years in which the temporary differences are expected to be recovered or paid. Accordingly, the company’s deferred tax assets and liabilities were adjusted to reflect the reduction in the U.S. corporate income tax rate from 35 percent to 21 percent, resulting in a $24.9 million increase in income tax expense for the year ended December 31, 2017 and a corresponding $24.9 million decrease in net deferred tax assets as of December 31, 2017.

Transition Tax on Foreign Earnings

The company recognized a provisional income tax expense of $13.9 million for the year ended December 31, 2017 related to the one-time transition tax on indefinitely reinvested foreign earnings. The determination of the transition tax requires further analysis regarding the amount and composition of the company’s historical foreign earnings, the amount of foreign tax credits available, and the ability to utilize certain foreign tax credits, which is expected to be completed in 2018.

The adjustments to the deferred tax assets and liabilities and the liability for the transition tax on indefinitely reinvested foreign earnings, including the analysis of our ability to fully utilize foreign tax credits associated with the transition tax, are provisional amounts estimated based on information reviewed as of December 31, 2017. As we complete our analysis of the Tax Act, review all information, collect and prepare necessary data, and interpret any additional guidance, we may make adjustments to the provisional amounts that we have recorded as of December 31, 2017 that may materially impact our provision for income taxes. Any subsequent adjustment will be recorded to current income tax expense in the quarter of 2018 when the analysis is completed.

Income (loss) before income taxes is as follows:



	Year Ended December 31,
(In thousands)	2017			2016		2015
Income (loss) before income taxes:
United States	$	(131,475	)	$	251,321	$	272,739
Foreign	121,166			136,961		113,946
Total	$	(10,309	)	$	388,282	$	386,685

The components of the provision for income taxes consisted of the following:



	Year Ended December 31,
(In thousands)	2017			2016			2015
Current
Federal	$	(46,931	)	$	116,637		$	102,317
State	(8,336		)	29,989			27,500
Other foreign countries	34,005			32,394			28,336
	(21,262		)	179,020			158,153
Deferred
Federal	51,447			(35,748		)	707
State	12,080			(10,658		)	(5,703		)
Other foreign countries	(4,314		)	(1,311		)	955
	59,213			(47,717		)	(4,041		)
Provision for income taxes	$	37,951		$	131,303		$	154,112

A reconciliation from the U.S. statutory federal income tax rate to the effective income tax rate is as follows:



	Year Ended December 31,
	2017					2016					2015
U.S. federal statutory income tax rate	$	(3,608	)	35.0	%	$	135,899		35.0	%	$	135,340		35.0	%
State taxes, net of federal tax impact	(9,537		)	92.5		9,447			2.4		12,252			3.2
Unrecognized tax benefits	1,178			(11.4	)	4,377			1.1		12,931			3.4
Permanent tax benefits/nondeductible expenses	2,246			(21.8	)	(5,177		)	(1.3	)	8,475			2.2
Goodwill impairment	8,522			(82.7	)	—			—		—			—
Foreign rate differential	(25,563		)	248.0		(25,768		)	(6.6	)	(21,262		)	(5.5	)
Valuation allowance	29,563			(290.3	)	8,798			2.3		10,504			2.7
Impacts related to Tax Act	38,833			(376.7	)	—			—		—			—
Other	(3,683		)	39.2		3,727			0.9		(4,128		)	(1.1	)
Effective income tax rate	$	37,951		(368.2	)%	$	131,303		33.8	%	$	154,112		39.9	%

The decrease in the 2017 full year effective income tax rate, as compared to 2016, is primarily attributable to the significant decrease in pre-tax earnings. In 2017, the Company recorded tax benefits for losses in the United States and reductions in the Company's total liability for unrecognized tax benefits as a result of a lapse in the statute of limitations during the current period. These benefits were offset by the impact of the Tax Act, non-deductible goodwill impairment charges and the recording of certain valuation allowances.

Deferred tax assets and liabilities consisted of the following:



	December 31,
(In thousands)	2017			2016
Deferred tax asset
Allowance for doubtful accounts and sales return reserves	$	52,745		$	53,811
Foreign net operating loss carry-forwards	34,542			26,964
Tax basis inventory adjustment	30,531			25,776
Reserves and accrued liabilities	20,500			38,819
Stock-based compensation	19,002			32,910
Deferred rent	18,735			21,168
U.S. net operating loss carryforward	13,382			3,032
Foreign tax credit carry-forwards	11,918			8,664
State tax credits, net of federal impact	8,555			7,408
Inventory obsolescence reserves	5,241			15,479
Other	4,340			3,107
Total deferred tax assets	219,491			237,138
Less: valuation allowance	(73,544		)	(37,969		)
Total net deferred tax assets	145,947			199,169

Deferred tax liability
Property, plant and equipment	(43,924		)	(45,178		)
Prepaid expenses	(18,336		)	(8,628		)
Intangible assets	—			(6,815		)
Other	(1,218		)	(2,506		)
Total deferred tax liabilities	(63,478		)	(63,127		)
Total deferred tax assets, net	$	82,469		$	136,042

All deferred tax assets and liabilities are classified in non-current on the Consolidated Balance Sheets as of December 31, 2017 and December 31, 2016. In evaluating its ability to realize the net deferred tax assets, the Company considered all available positive and negative evidence, including its past operating results and the forecast of future market growth, forecasted earnings, future taxable income, and prudent and feasible tax planning strategies. The assumptions utilized in determining future taxable income require significant judgment and actual operating results in future years could differ from our current assumptions, judgments and estimates.

A significant portion of the Company's deferred tax assets relate to U.S. federal and state taxing jurisdictions. Realization of these deferred tax assets is dependent on future U.S. pre-tax earnings. Due to the Company's losses in the United States, the Company incurred significant net operating losses (“NOLs”) in these jurisdictions in 2017. Based on these factors, the Company has evaluated its ability to utilize these deferred tax assets in future years. In evaluating the recoverability of these deferred tax assets at December 31, 2017, the Company has considered all available evidence, both positive and negative, including but not limited to the following:

Positive


•	Availability of taxable income in the U.S. federal and certain state NOL carryback periods;


•	U.S. federal NOLs have an indefinite carryforward period beginning in 2018, pursuant to the Tax Act.


•	Definite lived tax attributes with relatively long carryforward periods; a majority from 10 to 20 years;


•	No history of U.S. federal and state tax attributes expiring unused;


•	Three year cumulative U.S. federal and state pre-tax income;


•	Relatively low values of pre-tax income required to realized deferred tax assets relative to historic income levels;


•	Restructuring plans being undertaken to improve profitability; and


•	Availability of prudent and feasible tax planning strategies.

Negative


•	Inherent challenges in forecasting future pre-tax earnings which rely on improved profitability from our restructuring efforts;


•	The continuing challenge of changes in the U.S. consumer retail business environment; and


•	While relatively long, existence of definite lived tax attributes of certain U.S. federal tax credits and state NOLs.

Based on all available evidence considered, the Company believes it is more likely than not, that most of the U.S. federal and state deferred tax assets recorded will ultimately be realized. However, as of December 31, 2017, a valuation allowance of $15.9 million has been recorded against certain state deferred tax assets where the Company has determined realization is not more likely than not. Additionally, valuation allowances have been recorded against certain deferred tax assets associated with foreign and state net operating loss carryforwards and foreign and state tax credit carryforwards as discussed further below.

As of December 31, 2017, the Company had $34.5 million in deferred tax assets associated with approximately $116.0 million in foreign net operating loss carryforwards, the majority of which have an indefinite carryforward period. As of December 31, 2017, the Company is not able to forecast the utilization of the majority of the deferred tax assets associated with foreign net operating loss carryforwards. Therefore, a valuation allowance of $32.8 million was recorded against the Company's net deferred tax assets in 2017.

As of December 31, 2017 the Company had $13.4 million in deferred tax assets associated with $207.5 million in state net operating loss carryforwards, which will begin to expire in 3 to 20 years. As of December 31, 2017 the Company believes certain deferred tax assets associated with state net operating loss carryforwards will expire unused based on the Company’s projections. Therefore, a valuation allowance of $11.7 million is recorded against these net deferred tax assets as of December 31, 2017.

As of December 31, 2017, the Company had $11.9 million in deferred tax assets associated with foreign tax credits. As of December 31, 2017 the Company believes that a portion of the foreign taxes paid would not be creditable against its future income taxes. Therefore, a valuation allowance of $9.9 million was recorded against the Company's net deferred tax assets as of December 31, 2017.

As of December 31, 2017, the Company had $8.6 million in deferred tax assets associated with state tax credits, net of federal impact, which will begin to expire in 5 to 20 years. As of December 31, 2017, the Company is not able to forecast the utilization of certain deferred tax assets associated with state tax credits. Therefore a valuation allowance of $3.2 million is recorded against these net deferred tax assets as of December 31, 2017.

As of December 31, 2017, approximately $158.7 million of cash and cash equivalents was held by the Company's non-U.S. subsidiaries whose cumulative undistributed earnings total $488.4 million. These earnings were subject to the one-time transition tax on indefinitely reinvested foreign earnings required by the Tax Act. The Company will continue to permanently reinvest these earnings, as well as future earnings from our foreign subsidiaries, to fund international growth and operations.

As of December 31, 2017 and 2016, the total liability for unrecognized tax benefits, including related interest and penalties, was approximately $55.3 million and $70.4 million, respectively. The following table represents a reconciliation of the Company's total unrecognized tax benefits balances, excluding interest and penalties, for the years ended December 31, 2017, 2016 and 2015.



	Year Ended December 31,
(In thousands)	2017			2016			2015
Beginning of year	$	64,359		$	42,611		$	28,353
Increases as a result of tax positions taken in a prior period	457			661			203
Decreases as a result of tax positions taken in a prior period	(40		)	—			—
Increases as a result of tax positions taken during the current period	14,580			26,482			14,382
Decreases as a result of tax positions taken during the current period	—			—			—
Decreases as a result of settlements during the current period	(13,885		)	—			—
Reductions as a result of a lapse of statute of limitations during the current period	(13,656		)	(5,395		)	(327		)
End of year	$	51,815		$	64,359		$	42,611

As of December 31, 2017, $46.2 million of unrecognized tax benefits, excluding interest and penalties, would impact the Company's effective tax rate if recognized.

As of December 31, 2017 and 2016, the liability for unrecognized tax benefits included $3.5 million and $6.1 million, respectively, for the accrual of interest and penalties. For each of the years ended December 31, 2017, 2016 and 2015, the Company recorded $1.6 million, $3.1 million and $1.7 million, respectively, for the accrual of interest and penalties in its consolidated statements of operations. The Company recognizes accrued interest and penalties related to unrecognized tax benefits in the provision for income taxes on the consolidated statements of operations.

The Company files income tax returns in the U.S. federal jurisdiction and various state and foreign jurisdictions. The Company is currently under audit by the Internal Revenue Service for the 2015 and 2016 tax years. The majority of the Company's returns for years before 2014 are no longer subject to U.S. federal, state and local or foreign income tax examinations by tax authorities.

The total amount of unrecognized tax benefits relating to the Company's tax positions is subject to change based on future events including, but not limited to, the settlements of ongoing tax audits and assessments and the expiration of applicable statutes of limitations. Although the outcomes and timing of such events are highly uncertain, the Company does not anticipate that the balance of gross unrecognized tax benefits, excluding interest and penalties, will change significantly during the next twelve months. However, changes in the occurrence, expected outcomes, and timing of such events could cause the Company's current estimate to change materially in the future.

Earnings per Share

12 Months Ended

Dec. 31, 2017

Earnings Per Share [Abstract]

Earnings per Share

The calculation of earnings per share for common stock shown below excludes the income attributable to outstanding restricted stock awards from the numerator and excludes the impact of these awards from the denominator. The following is a reconciliation of basic earnings per share to diluted earnings per share:



	Year Ended December 31,
(In thousands, except per share amounts)	2017			2016		2015
Numerator
Net income (loss)	$	(48,260	)	$	256,979	$	232,573
Adjustment payment to Class C capital stockholders	—			59,000		—
Net income (loss) available to all stockholders	$	(48,260	)	$	197,979	$	232,573

Denominator - Class A and B shares
Weighted average common shares outstanding	219,254			217,707		215,498
Effect of dilutive securities	—			4,237		5,370
Weighted average common shares and dilutive securities outstanding	219,254			221,944		220,868
Earnings per share Class A and B —basic	$	(0.11	)	$	0.45	$	0.54
Earnings per share Class A and B—diluted	$	(0.11	)	$	0.45	$	0.53

Denominator - Class C shares
Weighted average common shares outstanding	221,475			218,623		215,498
Effect of dilutive securities	—			4,281		5,370
Weighted average common shares and dilutive securities outstanding	221,475			222,904		220,868
Earnings (loss) per share Class C — basic	$	(0.11	)	$	0.72	$	0.54
Earnings (loss) per share Class C — diluted	$	(0.11	)	$	0.71	$	0.53

Effects of potentially dilutive securities are presented only in periods in which they are dilutive. Stock options, restricted stock units and warrants representing 256.0 thousand, 114.0 thousand and 770.0 thousand shares of Class A common stock outstanding for the years ended December 31, 2017, 2016 and 2015, respectively, were excluded from the computation of diluted earnings per share because their effect would be anti-dilutive. Stock options, restricted stock units and warrants representing 4.7 million, 691.6 thousand and 770.0 thousand shares of Class C common stock outstanding for the years ended December 31, 2017, 2016 and 2015, respectively, were excluded from the computation of diluted earnings per share because their effect would be anti-dilutive.

Stock-Based Compensation

12 Months Ended

Dec. 31, 2017

Disclosure of Compensation Related Costs, Share-based Payments [Abstract]

Stock-Based Compensation

Stock Compensation Plans

The Under Armour, Inc. Second Amended and Restated 2005 Omnibus Long-Term Incentive Plan as amended (the “2005 Plan”) provides for the issuance of stock options, restricted stock, restricted stock units and other equity awards to officers, directors, key employees and other persons. Stock options and restricted stock and restricted stock unit awards under the 2005 Plan generally vest ratably over a two to five year period. The contractual term for stock options is generally ten years from the date of grant. The Company generally receives a tax deduction for any ordinary income recognized by a participant in respect to an award under the 2005 Plan. The 2005 Plan terminates in 2025. As of December 31, 2017, 7.9 million Class A shares and 15.5 million Class C shares are available for future grants of awards under the 2005 Plan.

Total stock-based compensation expense for the years ended December 31, 2017, 2016 and 2015 was $39.9 million, $46.1 million and $60.4 million, respectively. As of December 31, 2017, the Company had $87.7 million of unrecognized compensation expense expected to be recognized over a weighted average period of 3.2 years. This unrecognized compensation expense does not include any expense related to performance-based restricted stock units and stock options for which the performance targets have not been deemed probable as of December 31, 2017. Refer to “Stock Options” and “Restricted Stock and Restricted Stock Units” below for further information on these awards.

Employee Stock Purchase Plan

The Company’s Employee Stock Purchase Plan (the “ESPP”) allows for the purchase of Class A Common Stock and Class C Common Stock by all eligible employees at a 15% discount from fair market value subject to certain limits as defined in the ESPP. As of December 31, 2017, 2.7 million Class A shares and 1.2 million Class C shares are available for future purchases under the ESPP. During the years ended December 31, 2017, 2016 and 2015, 563.9 thousand, 290.8 thousand and 103.3 thousand shares were purchased under the ESPP, respectively.

Non-Employee Director Compensation Plan and Deferred Stock Unit Plan

The Company’s Non-Employee Director Compensation Plan (the “Director Compensation Plan”) provides for cash compensation and equity awards to non-employee directors of the Company under the 2005 Plan. Non-employee directors have the option to defer the value of their annual cash retainers as deferred stock units in accordance with the Under Armour, Inc. Non-Employee Deferred Stock Unit Plan (the “DSU Plan”). Each new non-employee director receives an award of restricted stock units upon the initial election to the Board of Directors, with the units covering stock valued at $100.0 thousand on the grant date and vesting in three equal annual installments. In addition, each non-employee director receives, following each annual stockholders’ meeting, a grant under the 2005 Plan of restricted stock units covering stock valued at $150.0 thousand on the grant date. Each award vests 100% on the date of the next annual stockholders’ meeting following the grant date.

The receipt of the shares otherwise deliverable upon vesting of the restricted stock units automatically defers into deferred stock units under the DSU Plan. Under the DSU Plan each deferred stock unit represents the Company’s obligation to issue one share of the Company’s Class C Common Stock with the shares delivered six months following the termination of the director’s service.

Stock Options

The weighted average fair value of a stock option granted for the years ended December 31, 2017, 2016, and 2015 was $19.04, $14.87, and $27.21 respectively. The fair value of each stock option granted is estimated on the date of grant using the Black-Scholes option-pricing model with the following weighted average assumptions:



	Year Ended December 31,
	2017		2016		2015
Risk-free interest rate	2.1	%	1.4	%	1.8	%
Average expected life in years	6.50		6.50		6.00
Expected volatility	39.6	%	39.5	%	44.3	%
Expected dividend yield	—	%	—	%	—	%

A summary of the Company’s stock options as of December 31, 2017, 2016 and 2015, and changes during the years then ended is presented below:



(In thousands, except per share amounts)	Year Ended December 31,
(In thousands, except per share amounts)	2017				2016				2015
	Number of Stock Options		Weighted Average Exercise Price		Number of Stock Options		Weighted Average Exercise Price		Number of Stock Options		Weighted Average Exercise Price
Outstanding, beginning of year	4,265		$	9.63	6,008		$	7.26	5,622		$	4.14
Granted, at fair market value	734		19.04		335		36.05		1,158		20.15
Exercised	(1,046	)	3.72		(1,763	)	3.52		(720	)	3.96
Expired	—		—		—		—		—		—
Forfeited	(171	)	17.59		(315	)	26.26		(52	)	2.27
Outstanding, end of year	3,782		$	12.71	4,265		$	9.63	6,008		$	7.26
Options exercisable, end of year	2,512		$	5.85	3,385		$	4.30	4,892		$	4.13

Included in the table above are 0.5 million and 0.3 million performance-based stock options awarded to certain executives and key employees under the 2005 Plan during the years ended December 31, 2017 and 2016, respectively. The performance-based stock options awarded in 2017 and 2016 have weighted average grant date fair values of $19.04 and $14.87, respectively, and have vesting that is tied to the achievement of certain combined annual operating income targets.

The intrinsic value of stock options exercised during the years ended December 31, 2017, 2016 and 2015 was $16.3 million, $63.9 million and $27.5 million, respectively.

The following table summarizes information about stock options outstanding and exercisable as of December 31, 2017:

(In thousands, except per share amounts)



Options Outstanding						Options Exercisable
Number of Underlying Shares	Weighted Average Exercise Price Per Share		Weighted Average Remaining Contractual Life (Years)	Total Intrinsic Value		Number of Underlying Shares	Weighted Average Exercise Price Per Share		Weighted Average Remaining Contractual Life (Years)	Total Intrinsic Value
3,782	$	12.71	4.55	$	22,679	2,512	$	5.85	2.52	$	22,553

Restricted Stock and Restricted Stock Units

A summary of the Company’s restricted stock and restricted stock units as of December 31, 2017, 2016 and 2015, and changes during the years then ended is presented below:



	Year Ended December 31,
	2017				2016				2015
(In thousands, except per share amounts)	Number of Restricted Shares		Weighted Average Grant Date Fair Value		Number of Restricted Shares		Weighted Average Fair Value		Number of Restricted Shares		Weighted Average Fair Value
Outstanding, beginning of year	6,771		$	19.68	6,760		$	23.23	9,020		$	15.21
Granted	7,630		18.84		4,002		35.20		2,030		38.36
Forfeited	(2,290	)	28.71		(935	)	30.35		(652	)	24.29
Vested	(2,188	)	24.78		(3,056	)	16.25		(3,638	)	11.61
Outstanding, end of year	9,923		24.41		6,771		19.68		6,760		23.23

Included in the table above are 1.9 million, 2.5 million and 1.7 million performance-based restricted stock units awarded to certain executives and key employees under the 2005 Plan during the years ended December 31, 2017, 2016 and 2015, respectively. The performance-based restricted stock units awarded in 2017, 2016 and 2015 have weighted average grant date fair values of $18.76, $35.71 and $37.87, respectively, and have vesting that is tied to the achievement of certain combined annual operating income targets.

During the year ended December 31, 2017, the Company deemed the achievement of certain revenue and operating income targets improbable for the performance-based stock options and restricted stock units granted in 2017, and recorded a reversal of expense of $4.2 million for the three months ended December 31, 2017. During the year ended December 31, 2016, the Company deemed the achievement of certain operating income targets improbable for the performance-based stock options and restricted stock units granted in 2015 and 2016, and recorded reversals of expense of $3.6 million and $8.0 million, respectively, for the three months ended December 31, 2016. During the year ended December 31, 2015, the Company deemed the achievement of certain operating income targets probable for the performance-based stock options and restricted stock units granted in 2015 and 2014, and recorded $33.2 million for these awards, including a cumulative adjustment of $10.0 million during the three months ended September 30, 2015. The Company will assess the probability of the achievement of the operating income targets at the end of each reporting period. If it becomes probable that any remaining performance targets related to these performance-based stock options and restricted stock units will be achieved, a cumulative adjustment will be recorded as if ratable stock-based compensation expense had been recorded since the grant date. Additional stock based compensation of up to $5.7 million would have been recorded through December 31, 2017 for all performance-based stock options and restricted stock units granted in 2017 had the full achievement of these operating income targets been deemed probable.

Warrants

In 2006, the Company issued fully vested and non-forfeitable warrants to purchase 1.92 million shares of the Company's Class A Common Stock and 1.93 million shares of the Company’s Class C Common Stock to NFL Properties as partial consideration for footwear promotional rights which were recorded as an intangible asset. The warrants have a term of 12 years from the date of issuance and an exercise price of $4.66 per Class A share and $4.59 per Class C share. As of December 31, 2017, all outstanding warrants were exercisable, and no warrants were exercised.

Other Employee Benefits	12 Months Ended
Other Employee Benefits	Dec. 31, 2017
Compensation Related Costs [Abstract]
Other Employee Benefits	Other Employee Benefits The Company offers a 401(k) Deferred Compensation Plan for the benefit of eligible employees. Employee contributions are voluntary and subject to Internal Revenue Service limitations. The Company matches a portion of the participant’s contribution and recorded expense of $7.4 million, $9.0 million and $7.0 million for the years ended December 31, 2017, 2016 and 2015, respectively. Shares of the Company’s Class A Common Stock and Class C common stock are not investment options in this plan. In addition, the Company offers the Under Armour, Inc. Deferred Compensation Plan which allows a select group of management or highly compensated employees, as approved by the Compensation Committee, to make an annual base salary and/or bonus deferral for each year. As of December 31, 2017 and 2016, the Deferred Compensation Plan obligations were $8.0 million and $7.0 million, respectively, and were included in other long term liabilities on the consolidated balance sheets. The Company established the Rabbi Trust to fund obligations to participants in the Deferred Compensation Plan. As of December 31, 2017 and 2016, the assets held in the Rabbi Trust were TOLI policies with cash-surrender values of $5.8 million and $4.9 million, respectively. These assets are consolidated and are included in other long term assets on the consolidated balance sheet. Refer to Note 9 for a discussion of the fair value measurements of the assets held in the Rabbi Trust and the Deferred Compensation Plan obligations.

Risk Management and Derivatives

12 Months Ended

Dec. 31, 2017

Derivative Instruments and Hedging Activities Disclosure [Abstract]

Foreign Currency Risk Management and Derivatives

Risk Management and Derivatives

Foreign Currency Risk Management

The Company is exposed to gains and losses resulting from fluctuations in foreign currency exchange rates relating to transactions generated by its international subsidiaries in currencies other than their local currencies. These gains and losses are primarily driven by intercompany transactions and inventory purchases denominated in currencies other than the functional currency of the purchasing entity. From time to time, the Company may elect to enter into foreign currency contracts to reduce the risk associated with foreign currency exchange rate fluctuations on intercompany transactions and projected inventory purchases for its international subsidiaries.

As of December 31, 2017, the aggregate notional value of the Company's outstanding foreign currency contracts was $601.0 million, which had contract maturities ranging from one to eleven months. A portion of the Company's foreign currency contracts are not designated as cash flow hedges, and accordingly, changes in their fair value are recorded in earnings. The Company enters into foreign currency contracts designated as cash flow hedges. For foreign currency contracts designated as cash flow hedges, changes in fair value, excluding any ineffective portion, are recorded in other comprehensive income until net income is affected by the variability in cash flows of the hedged transaction. The effective portion is generally released to net income after the maturity of the related derivative and is classified in the same manner as the underlying exposure. During the years ended December 31, 2017 and 2016, the Company reclassified $0.4 million and $0.3 million from other comprehensive income to cost of goods sold related to foreign currency contracts designated as cash flow hedges, respectively. The fair value of the Company’s foreign currency contracts was a liability of $6.8 million as of December 31, 2017 and was included in other current liabilities on the consolidated balance sheet. The fair value of the Company's foreign currency contracts was an asset of $15.2 million as of December 31, 2016 and was included in prepaid expenses and other current assets on the consolidated balance sheet. Refer to Note 9 for a discussion of the fair value measurements. Included in other expense, net were the following amounts related to changes in foreign currency exchange rates and derivative foreign currency contracts:



(In thousands)	Year Ended December 31,
(In thousands)	2017			2016			2015
Unrealized foreign currency exchange rate gains (losses)	$	29,246		$	(12,627	)	$	(33,359	)
Realized foreign currency exchange rate gains (losses)	611			(6,906		)	7,643
Unrealized derivative gains (losses)	(1,217		)	729			388
Realized derivative gains (losses)	(26,537		)	15,192			16,404

Interest Rate Risk Management

In order to maintain liquidity and fund business operations, the Company enters into long term debt arrangements with various lenders which bear a range of fixed and variable rates of interest. The nature and amount of the Company's long-term debt can be expected to vary as a result of future business requirements, market conditions and other factors. The Company may elect to enter into interest rate swap contracts to reduce the impact associated with interest rate fluctuations. The Company utilizes interest rate swap contracts to convert a portion of variable rate debt to fixed rate debt. The contracts pay fixed and receive variable rates of interest. The interest rate swap contracts are accounted for as cash flow hedges and accordingly, the effective portion of the changes in their fair value are recorded in other comprehensive income and reclassified into interest expense over the life of the underlying debt obligation. Refer to Note 6 for a discussion of long term debt.

As of December 31, 2017, the notional value of the Company's outstanding interest rate swap contracts was $135.6 million . During the years ended December 31, 2017 and 2016, the Company recorded a $0.9 million and $2.0 million increase in interest expense, respectively, representing the effective portion of the contracts reclassified from accumulated other comprehensive income. The fair value of the interest rate swap contracts was an asset of $1.1 million as of December 31, 2017 and was included in other long term assets on the consolidated balance sheet. The fair value of the interest rate swap contracts was a liability of $0.4 million as of December 31, 2016 and was included in other long term liabilities on the consolidated balance sheet.

The Company enters into derivative contracts with major financial institutions with investment grade credit ratings and is exposed to credit losses in the event of non-performance by these financial institutions. This credit risk is generally limited to the unrealized gains in the derivative contracts. However, the Company monitors the credit quality of these financial institutions and considers the risk of counterparty default to be minimal.

Related Party Transactions	12 Months Ended
Related Party Transactions	Dec. 31, 2017
Related Party Transactions [Abstract]
Related Party Transactions	Related Party Transactions The Company has an operating lease agreement with an entity controlled by the Company’s Chief Executive Officer to lease an aircraft for business purposes. The Company paid $2.0 million, $2.0 million, and $2.0 million in lease payments to the entity for its use of the aircraft during the years ended December 31, 2017, 2016 and 2015, respectively. No amounts were payable to this related party as of December 31, 2017 and 2016. The Company determined the lease payments were at fair market lease rates. In June 2016, the Company purchased parcels of land from an entity controlled by the Company's CEO, to be utilized to expand the Company’s corporate headquarters to accommodate its growth needs. The purchase price for these parcels totaled $70.3 million. The Company determined that the purchase price for the land represented the fair market value of the parcels and approximated the cost to the seller to purchase and develop the parcels, including costs related to the termination of a lease encumbering the parcels. In connection with the purchase of these parcels, in September 2016, the parties entered into an agreement pursuant to which the parties will share the burden of any special taxes arising due to infrastructure projects in the surrounding area. The allocation to the Company is based on the expected benefits to the Company’s parcels from these projects. No obligations were owed by either party under this agreement as of December 31, 2017.

Segment Data and Related Information

12 Months Ended

Dec. 31, 2017

Segment Reporting [Abstract]

Segment Data and Related Information

The Company’s operating segments are based on how the Chief Operating Decision Maker (“CODM”) makes decisions about allocating resources and assessing performance. As such, the CODM receives discrete financial information for the Company's principal business by geographic region based on the Company’s strategy to become a global brand. These geographic regions include North America; Latin America; Europe, the Middle East and Africa (“EMEA”); and Asia-Pacific. Each geographic segment operates exclusively in one industry: the development, marketing and distribution of branded performance apparel, footwear and accessories. The CODM also receives discrete financial information for the Company's Connected Fitness business.

The net revenues and operating income (loss) associated with the Company's segments are summarized in the following tables. Net revenues represent sales to external customers for each segment. Intercompany balances were eliminated for separate disclosure. The majority of corporate service costs within North America have not been allocated to the Company's other segments. As the Company continues to grow its business outside of North America, a larger portion of its corporate overhead costs have begun to support global functions. Total expenditures for additions to long-lived assets are not disclosed as this information is not regularly provided to the CODM.



(In thousands)	Year Ended December 31,
(In thousands)	2017		2016			2015
Net revenues
North America	$	3,802,406	$	4,005,314		$	3,455,737
EMEA	469,997		330,584			203,109
Asia-Pacific	433,647		268,607			144,877
Latin America	181,324		141,793			106,175
Connected Fitness	89,179		80,447			53,415
Intersegment Eliminations	—		(1,410		)	—
Total net revenues	$	4,976,553	$	4,825,335		$	3,963,313

Net revenues in the United States were $3,626.6 million, $3,843.7 million, and $3,317.0 million for the years ended December 31, 2017, 2016 and 2015, respectively.



(In thousands)	Year Ended December 31,
(In thousands)	2017			2016			2015
Operating income (loss)
North America	$	20,179		$	408,424		$	460,961
EMEA	17,976			11,420			3,122
Asia-Pacific	82,039			68,338			36,358
Latin America	(37,085		)	(33,891		)	(30,593		)
Connected Fitness	(55,266		)	(36,820		)	(61,301		)
Total operating income	27,843			417,471			408,547
Interest expense, net	(34,538		)	(26,434		)	(14,628		)
Other expense, net	(3,614		)	(2,755		)	(7,234		)
Income (loss) before income taxes	$	(10,309	)	$	388,282		$	386,685

The operating income information presented above includes the impact of restructuring and impairment charges related to each of the Company's 2017 restructuring plan and 2018 restructuring plan. Charges incurred and expected to be incurred by segment in connection with each of the respective restructuring plans are as follows:



(In thousands)	Costs Incurred During the Year Ended December 31, 2017 (1)		Costs to be Incurred During the Year Ending December 31, 2018
Costs recorded in restructuring and impairment charges:
North America	$	63,170	$	109,000
EMEA	1,525		6,000
Asia-Pacific	38		—
Latin America	11,506		18,000
Connected Fitness	47,810		—
Total costs recorded in restructuring and impairment charges	$	124,049	$	133,000

(1) This table excludes additional non-cash charges of $5.1 million associated with the reduction of inventory outside of current liquidation channels in line with the 2017 restructuring plan.

Long-lived assets are primarily composed of Property and equipment, net. The Company's long-lived assets by geographic area were as follows:



(In thousands)	Year Ended December 31,
(In thousands)	2017		2016
Long-lived assets
United States	$	763,477	$	728,841
Canada	14,077		11,126
Total North America	777,554		739,967
Other foreign countries	108,220		64,244
Total long lived assets	$	885,774	$	804,211

Net revenues by product category are as follows:



(In thousands)	Year Ended December 31,
(In thousands)	2017		2016			2015
Apparel	$	3,287,121	$	3,229,142		$	2,801,062
Footwear	1,037,840		1,010,693			677,744
Accessories	445,838		406,614			346,885
Total net sales	4,770,799		4,646,449			3,825,691
Licensing revenues	116,575		99,849			84,207
Connected Fitness	89,179		80,447			53,415
Intersegment Eliminations	—		(1,410		)	—
Total net revenues	$	4,976,553	$	4,825,335		$	3,963,313

Net revenues in the United States were $3,626.6 million, $3,843.7 million, and $3,317.0 million for the years ended December 31, 2017, 2016 and 2015, respectively.

Unaudited Quarterly Financial Data

12 Months Ended

Dec. 31, 2017

Quarterly Financial Data [Abstract]

Unaudited Quarterly Financial Data



(In thousands)	Quarter Ended (unaudited)											Year Ended December 31,
(In thousands)	March 31,			June 30,			September 30,		December 31,			Year Ended December 31,
2017
Net revenues	$	1,117,331		$	1,088,245		$	1,405,615	$	1,365,362		$	4,976,553
Gross profit	505,423			498,246			645,350		589,704			2,238,723
Income (loss) from operations	7,536			(4,785		)	62,180		(37,088		)	27,843
Net income (loss)	(2,272		)	(12,308		)	54,242		(87,922		)	(48,260		)
Net income (loss) available to all stockholders	$	(2,272	)	$	(12,308	)	$	54,242	$	(87,922	)	$	(48,260	)
Basic net income (loss) per share of Class A and B common stock	$	(0.01	)	$	(0.03	)	$	0.12	$	(0.20	)	$	(0.11	)
Basic net income (loss) per share of Class C common stock	$	(0.01	)	$	(0.03	)	$	0.12	$	(0.20	)	$	(0.11	)
Diluted net income (loss) per share of Class A and B common stock	$	(0.01	)	$	(0.03	)	$	0.12	$	(0.20	)	$	(0.11	)
Diluted net income (loss) per share of Class C common stock	$	(0.01	)	$	(0.03	)	$	0.12	$	(0.20	)	$	(0.11	)

2016
Net revenues	$	1,047,702		$	1,000,783		$	1,471,573	$	1,305,277		$	4,825,335
Gross profit	480,636			477,647			698,624		583,704			2,240,611
Income from operations	34,883			19,378			199,310		163,900			417,471
Net income	19,180			6,344			128,225		103,230			256,979
Adjustment payment to Class C capital stockholders	—			59,000			—		—			59,000
Net income (loss) available to all stockholders	19,180			(52,656		)	128,225		103,230			197,979
Basic net income (loss) per share of Class A and B common stock	$	0.04		$	(0.12	)	$	0.29	$	0.24		$	0.45
Basic net income (loss) per share of Class C common stock	$	0.04		$	0.15		$	0.29	$	0.24		$	0.72
Diluted net income (loss) per share of Class A and B common stock	$	0.04		$	(0.12	)	$	0.29	$	0.23		$	0.45
Diluted net income (loss) per share of Class C common stock	$	0.04		$	0.15		$	0.29	$	0.23		$	0.71

Basic and diluted net income (loss) per share are computed independently for each of the periods presented. Accordingly, the sum of the quarterly EPS amounts may not equal the total for the year.

Schedule II - Valuation And Qualifying Accounts

12 Months Ended

Dec. 31, 2017

Valuation and Qualifying Accounts [Abstract]

Valuation And Qualifying Accounts

Schedule II

Valuation and Qualifying Accounts

(In thousands)



Description	Balance at Beginning of Year		Charged to Costs and Expenses		Write-Offs Net of Recoveries			Balance at End of Year
Allowance for doubtful accounts
For the year ended December 31, 2017	$	11,341	$	9,520	$	(1,149	)	$	19,712
For the year ended December 31, 2016	5,930		23,575		(18,164		)	11,341
For the year ended December 31, 2015	3,693		2,951		(714		)	5,930
Sales returns and allowances
For the year ended December 31, 2017	$	121,286	$	285,474	$	(215,966	)	$	190,794
For the year ended December 31, 2016	72,615		179,445		(130,774		)	121,286
For the year ended December 31, 2015	52,973		145,828		(126,186		)	72,615
Deferred tax asset valuation allowance
For the year ended December 31, 2017	$	37,969	$	40,282	$	(4,707	)	$	73,544
For the year ended December 31, 2016	24,043		13,951		(25		)	37,969
For the year ended December 31, 2015	15,550		8,493		—			24,043

Summary of Significant Accounting Policies (Policies)	12 Months Ended
Summary of Significant Accounting Policies (Policies)	Dec. 31, 2017
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation The accompanying consolidated financial statements include the accounts of Under Armour, Inc. and its wholly owned subsidiaries (the “Company”). All intercompany balances and transactions have been eliminated. The accompanying consolidated financial statements were prepared in accordance with accounting principles generally accepted in the United States of America.
Cash and Cash Equivalents	Cash and Cash Equivalents The Company considers all highly liquid investments with an original maturity of three months or less at date of inception to be cash and cash equivalents.
Concentration of Credit Risk	Concentration of Credit Risk Financial instruments that subject the Company to significant concentration of credit risk consist primarily of accounts receivable. The majority of the Company’s accounts receivable is due from large sporting goods retailers. Credit is extended based on an evaluation of the customer’s financial condition and collateral is not required.
Allowance for Doubtful Accounts	Allowance for Doubtful Accounts The Company makes ongoing estimates relating to the collectability of accounts receivable and maintains an allowance for estimated losses resulting from the inability of its customers to make required payments. In determining the amount of the reserve, the Company considers historical levels of credit losses and significant economic developments within the retail environment that could impact the ability of its customers to pay outstanding balances and makes judgments about the creditworthiness of significant customers based on ongoing credit evaluations. Because the Company cannot predict future changes in the financial stability of its customers, actual future losses from uncollectible accounts may differ from estimates. If the financial condition of customers were to deteriorate, resulting in their inability to make payments, a larger reserve might be required. In the event the Company determines a smaller or larger reserve is appropriate, it would record a benefit or charge to selling, general and administrative expense in the period in which such a determination was made.
Inventories	Inventories Inventories consist primarily of finished goods. Costs of finished goods inventories include all costs incurred to bring inventory to its current condition, including inbound freight, duties and other costs. The Company values its inventory at standard cost which approximates landed cost, using the first-in, first-out method of cost determination. Market value is estimated based upon assumptions made about future demand and retail market conditions. If the Company determines that the estimated market value of its inventory is less than the carrying value of such inventory, it records a charge to cost of goods sold to reflect the lower of cost or market. If actual market conditions are less favorable than those projected by the Company, further adjustments may be required that would increase the cost of goods sold in the period in which such a determination was made.
Income Taxes	Income Taxes Income taxes are accounted for under the asset and liability method. Deferred income tax assets and liabilities are established for temporary differences between the financial reporting basis and the tax basis of the Company’s assets and liabilities at tax rates expected to be in effect when such assets or liabilities are realized or settled. Deferred income tax assets are reduced by valuation allowances when necessary. Assessing whether deferred tax assets are realizable requires significant judgment. The Company considers all available positive and negative evidence, including historical operating performance and expectations of future operating performance. The ultimate realization of deferred tax assets is often dependent upon future taxable income and therefore can be uncertain. To the extent the Company believes it is more likely than not that all or some portion of the asset will not be realized, valuation allowances are established against the Company’s deferred tax assets, which increase income tax expense in the period when such a determination is made. Income taxes include the largest amount of tax benefit for an uncertain tax position that is more likely than not to be sustained upon audit based on the technical merits of the tax position. Settlements with tax authorities, the expiration of statutes of limitations for particular tax positions, or obtaining new information on particular tax positions may cause a change to the effective tax rate. The Company recognizes accrued interest and penalties related to unrecognized tax benefits in the provision for income taxes on the consolidated statements of income.
Property and Equipment	Property and Equipment Property and equipment are stated at cost, including the cost of internal labor for software customized for internal use, less accumulated depreciation and amortization. Property and equipment is depreciated using the straight-line method over the estimated useful lives of the assets: 3 to 10 years for furniture, office equipment, software and plant equipment and 10 to 35 years for site improvements, buildings and building equipment. Leasehold and tenant improvements are amortized over the shorter of the lease term or the estimated useful lives of the assets. The cost of in-store apparel and footwear fixtures and displays are capitalized, included in furniture, fixtures and displays, and depreciated over 3 years. The Company periodically reviews assets’ estimated useful lives based upon actual experience and expected future utilization. A change in useful life is treated as a change in accounting estimate and is applied prospectively. The Company capitalizes the cost of interest for long term property and equipment projects based on the Company’s weighted average borrowing rates in place while the projects are in progress. Capitalized interest was $2.1 million and $1.8 million as of December 31, 2017 and 2016, respectively. Upon retirement or disposition of property and equipment, the cost and accumulated depreciation are removed from the accounts and any resulting gain or loss is reflected in selling, general and administrative expenses for that period. Major additions and betterments are capitalized to the asset accounts while maintenance and repairs, which do not improve or extend the lives of assets, are expensed as incurred.
Goodwill, Intangible Assets and Long-Lived Assets	Goodwill, Intangible Assets and Long-Lived Assets Goodwill and intangible assets are recorded at their estimated fair values at the date of acquisition and are allocated to the reporting units that are expected to receive the related benefits. Goodwill and indefinite lived intangible assets are not amortized and are required to be tested for impairment at least annually or sooner whenever events or changes in circumstances indicate that the assets may be impaired. In conducting an annual impairment test, the Company first reviews qualitative factors to determine whether it is more likely than not that the fair value of the reporting unit is less than its carrying amount. If factors indicate that is the case, the Company performs the goodwill impairment test. The Company compares the fair value of the reporting unit with its carrying amount. The Company calculates fair value using the discounted cash flows model, which indicates the fair value of the reporting unit based on the present value of the cash flows that the Company expects the reporting unit to generate in the future. The Company's significant estimates in the discounted cash flows model include: the Company's weighted average cost of capital, long-term rate of growth and profitability of the reporting unit’s business, and working capital effects. If the carrying amount exceeds its fair value, goodwill is impaired to the extent that the carrying value exceeds the fair value of the reporting unit. During the third quarter of 2017, the Company made the strategic decision to not pursue certain planned future revenue streams in its Connected Fitness business in connection with the 2017 Restructuring Plan. The Company determined sufficient indication existed to trigger the performance of an interim impairment for the Company’s Connected Fitness reporting unit resulting in goodwill impairment of $28.6 million, which represents all goodwill allocated to this reporting unit. The Company performs its annual impairment tests in the fourth quarter of each fiscal year. As of December 31, 2017, no impairment of goodwill was identified and the fair value of each reporting unit substantially exceeded its carrying value. The Company continually evaluates whether events and circumstances have occurred that indicate the remaining estimated useful life of long-lived assets may warrant revision or that the remaining balance may not be recoverable. These factors may include a significant deterioration of operating results, changes in business plans, or changes in anticipated cash flows. When factors indicate that an asset should be evaluated for possible impairment, the Company reviews long-lived assets to assess recoverability from future operations using undiscounted cash flows. If future undiscounted cash flows are less than the carrying value, an impairment is recognized in earnings to the extent that the carrying value exceeds fair value. In connection with the Company's 2017 Restructuring Plan, strategic decisions were made during the third quarter in 2017 to abandon the use of certain intangible assets in the Company's Connected Fitness reporting unit.
Accrued Expenses	Accrued Expenses At December 31, 2017, accrued expenses primarily included $92.7 million and $47.0 million of accrued compensation and benefits and marketing expenses, respectively. At December 31, 2016, accrued expenses primarily included $60.8 million and $24.7 million of accrued compensation and benefits and marketing expenses, respectively.
Foreign Currency Translation and Transactions	Foreign Currency Translation and Transactions The functional currency for each of the Company’s wholly owned foreign subsidiaries is generally the applicable local currency. The translation of foreign currencies into U.S. dollars is performed for assets and liabilities using current foreign currency exchange rates in effect at the balance sheet date and for revenue and expense accounts using average foreign currency exchange rates during the period. Capital accounts are translated at historical foreign currency exchange rates. Translation gains and losses are included in stockholders’ equity as a component of accumulated other comprehensive income. Adjustments that arise from foreign currency exchange rate changes on transactions, primarily driven by intercompany transactions, denominated in a currency other than the functional currency are included in other expense, net on the consolidated statements of income.
Derivatives and Hedging Activities	Derivatives and Hedging Activities The Company uses derivative financial instruments in the form of foreign currency and interest rate swap contracts to minimize the risk associated with foreign currency exchange rate and interest rate fluctuations. The Company accounts for derivative financial instruments pursuant to applicable accounting guidance. This guidance establishes accounting and reporting standards for derivative financial instruments and requires all derivatives to be recognized as either assets or liabilities on the balance sheet and to be measured at fair value. Unrealized derivative gain positions are recorded as other current assets or other long term assets, and unrealized derivative loss positions are recorded as other current liabilities or other long term liabilities, depending on the derivative financial instrument’s maturity date. Currently, the majority of the Company’s foreign currency contracts are not designated as cash flow hedges, and accordingly, changes in their fair value are included in other expense, net on the consolidated statements of income. During 2014, the Company began entering into foreign currency contracts designated as cash flow hedges, and consequently, changes in fair value, excluding any ineffective portion, are recorded in other comprehensive income until net income is affected by the variability in cash flows of the hedged transaction. The effective portion is generally released to net income after the maturity of the related derivative and is classified in the same manner as the underlying exposure. Additionally, the Company has designated its interest rate swap contract as a cash flow hedge and accordingly, the effective portion of changes in fair value are recorded in other comprehensive income and reclassified into interest expense over the life of the underlying debt obligation. The ineffective portion, if any, is recognized in current period earnings. The Company does not enter into derivative financial instruments for speculative or trading purposes.
Revenue Recognition	Revenue Recognition The Company recognizes revenue pursuant to applicable accounting standards. Net revenues consist of both net sales and license and other revenues. Net sales are recognized upon transfer of ownership, including passage of title to the customer and transfer of risk of loss related to those goods. Transfer of title and risk of loss is based upon shipment under free on board shipping point for most goods or upon receipt by the customer depending on the country of the sale and the agreement with the customer. In some instances, transfer of title and risk of loss takes place at the point of sale, for example, at the Company’s brand and factory house stores. The Company may also ship product directly from its supplier to the customer and recognize revenue when the product is delivered to and accepted by the customer. License and other revenues are primarily recognized based upon shipment of licensed products sold by the Company’s licensees. Sales taxes imposed on the Company’s revenues from product sales are presented on a net basis on the consolidated statements of income and therefore do not impact net revenues or costs of goods sold. The Company records reductions to revenue for estimated customer returns, allowances, markdowns and discounts. The Company bases its estimates on historical rates of customer returns and allowances as well as the specific identification of outstanding returns, markdowns and allowances that have not yet been received by the Company. The actual amount of customer returns and allowances, which is inherently uncertain, may differ from the Company’s estimates. If the Company determines that actual or expected returns or allowances are significantly higher or lower than the reserves it established, it would record a reduction or increase, as appropriate, to net sales in the period in which it makes such a determination. Provisions for customer specific discounts are based on contractual obligations with certain major customers. Reserves for returns, allowances, markdowns and discounts are recorded as an offset to accounts receivable as settlements are made through offsets to outstanding customer invoices.
Advertising Costs	Advertising Costs Advertising costs are charged to selling, general and administrative expenses. Advertising production costs are expensed the first time an advertisement related to such production costs is run. Media (television, print and radio) placement costs are expensed in the month during which the advertisement appears, and costs related to event sponsorships are expensed when the event occurs. In addition, advertising costs include sponsorship expenses. Accounting for sponsorship payments is based upon specific contract provisions and the payments are generally expensed uniformly over the term of the contract after recording expense related to specific performance incentives once they are deemed probable.
Shipping and Handling Costs	Shipping and Handling Costs The Company charges certain customers shipping and handling fees. These fees are recorded in net revenues. The Company includes the majority of outbound handling costs as a component of selling, general and administrative expenses. Outbound handling costs include costs associated with preparing goods to ship to customers and certain costs to operate the Company’s distribution facilities. These costs, included within selling, general and administrative expenses, were $101.5 million, $89.9 million and $63.7 million for the years ended December 31, 2017, 2016 and 2015, respectively. The Company includes outbound freight costs associated with shipping goods to customers as a component of cost of goods sold.
Minority Investment	Minority Investment The Company holds a minority investment in Dome Corporation (“Dome”), the Company’s Japanese licensee. The Company invested ¥1,140.0 million, or $15.5 million, in exchange for 19.5% common stock ownership in Dome. As of December 31, 2017 and 2016, the carrying value of the Company’s investment was $12.7 million and $11.7 million, respectively, and was included in other long term assets on the consolidated balance sheets. The investment is subject to foreign currency translation rate fluctuations as it is held by the Company’s European subsidiary. The Company accounts for its investment in Dome under the cost method given that it does not have the ability to exercise significant influence. Additionally, the Company concluded that no event or change in circumstances occurred during the year ended December 31, 2017 that may have a significant adverse effect on the fair value of the investment.
Earnings per Share	Earnings per Share Basic earnings per common share is computed by dividing net income available to common stockholders for the period by the weighted average number of common shares outstanding during the period. Any stock-based compensation awards that are determined to be participating securities, which are stock-based compensation awards that entitle the holders to receive dividends prior to vesting, are included in the calculation of basic earnings per share using the two class method. Diluted earnings per common share is computed by dividing net income available to common stockholders for the period by the diluted weighted average common shares outstanding during the period. Diluted earnings per share reflects the potential dilution from common shares issuable through stock options, warrants, restricted stock units and other equity awards.
Stock-Based Compensation	Stock-Based Compensation The Company accounts for stock-based compensation in accordance with accounting guidance that requires all stock-based compensation awards granted to employees and directors to be measured at fair value and recognized as an expense in the financial statements. In addition, this guidance requires that excess tax benefits related to stock-based compensation awards be reflected as operating cash flows. The Company uses the Black-Scholes option-pricing model to estimate the fair market value of stock-based compensation awards. The Company uses the “simplified method” to estimate the expected life of options, as permitted by accounting guidance. The “simplified method” calculates the expected life of a stock option equal to the time from grant to the midpoint between the vesting date and contractual term, taking into account all vesting tranches. The risk free interest rate is based on the yield for the U.S. Treasury bill with a maturity equal to the expected life of the stock option. Expected volatility is based on the Company's historical average. Compensation expense is recognized net of forfeitures on a straight-line basis over the total vesting period, which is the implied requisite service period. Compensation expense for performance-based awards is recorded over the implied requisite service period when achievement of the performance target is deemed probable. The Company issues new shares of Class A Common Stock and Class C Common Stock upon exercise of stock options, grant of restricted stock or share unit conversion.
Management Estimates	Management Estimates The preparation of financial statements in conformity with accounting principles generally accepted in the United States of America requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the consolidated financial statements and the reported amounts of revenues and expenses during the reporting period. Actual results could differ from these estimates.
Fair Value of Financial Instruments	Fair Value of Financial Instruments The carrying amounts shown for the Company’s cash and cash equivalents, accounts receivable and accounts payable approximate fair value because of the short term maturity of those instruments. The fair value of the Company's Senior Notes was $526.3 million and $568.1 million as of December 31, 2017 and 2016, respectively. The fair value of the Company's other long term debt approximates its carrying value based on the variable nature of interest rates and current market rates available to the Company. The fair value of foreign currency contracts is based on the net difference between the U.S. dollars to be received or paid at the contracts’ settlement date and the U.S. dollar value of the foreign currency to be sold or purchased at the current exchange rate. The fair value of the interest rate swap contract is based on the net difference between the fixed interest to be paid and variable interest to be received over the term of the contract based on current market rates.
Recently Issued Accounting Standards	Recently Issued Accounting Standards In May 2014, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update ("ASU") 2014-09, which supersedes the most current revenue recognition requirements. This ASU requires entities to recognize revenue in a way that depicts the transfer of goods or services to customers in an amount that reflects the consideration which the entity expects to be entitled to in exchange for those goods or services. This ASU will be effective for annual and interim periods beginning after December 15, 2017, with early adoption for annual and interim periods beginning after December 15, 2016 permitted. The Company’s initial assessment of the guidance in this ASU has identified wholesale customer support costs, direct to consumer incentive programs and customer related returns as transactions potentially affected by this guidance. On the Consolidated Balance Sheet, reserves for returns, allowances, discounts and markdowns will be included as other current liabilities rather than accounts receivable, net and the value of inventory associated with reserves for sales returns will be included within prepaid expenses and other current assets. While the Company has not completed its evaluation, it expects the impact of the adoption of this ASU would primarily change presentation within its consolidated financial statements but is currently not expected to have a material effect on income from operations. The Company will adopt the guidance in this new ASU effective January 1, 2018, and plans to use the modified retrospective transition approach, which would result in an adjustment to retained earnings for the cumulative effect, if any, of applying this guidance to contracts in effect as of the adoption date. Under this approach, the Company would not restate the prior financial statements presented. The guidance in this ASU requires the Company to provide additional disclosures of the amount by which each financial statement line item is affected in the current reporting period during 2018 as compared to the guidance that was in effect before the change, and an explanation of the reasons for significant changes, if any. In January of 2016, the FASB issued ASU 2016-01 which simplifies the impairment assessment of equity investments. This ASU requires equity investments to be measured at fair value with changes recognized in net income. This ASU eliminates the requirement to disclose the methods and assumptions to estimate fair value for financial instruments, requires the use of the exit price for disclosure purposes, requires the change in liability due to a change in credit risk to be presented in other comprehensive income, requires separate presentation of financial assets and liabilities by measurement category and form of asset (securities and loans) and clarifies the need for a valuation allowance on a deferred tax asset related to available-for-sale securities. The guidance in this ASU becomes effective for fiscal periods beginning January 1, 2018 using a cumulative-effect adjustment to the balance sheet. The guidance related to equity securities without readily determinable fair values (including disclosure requirements) shall be applied prospectively to equity investments that exist as of the date of adoption of this update. The Company does not believe the adoption of this ASU will have a material impact on its consolidated financial statements. In February 2016, the FASB issued ASU 2016-02, which amends the existing guidance for leases and will require recognition of operating leases with lease terms of more than twelve months and all financing leases on the balance sheet. For these leases, companies will record assets for the rights and liabilities for the obligations that are created by the leases. This ASU will require disclosures that provide qualitative and quantitative information for the lease assets and liabilities recorded in the financial statements. This ASU is effective for fiscal years beginning after December 15, 2018. The Company is currently evaluating this ASU to determine the impact of its adoption on its consolidated financial statements. The Company currently anticipates adopting the new standard effective January 1, 2019. The Company has formed a committee and initiated the review process for adoption of this ASU. While the Company is still in the process of completing its analysis on the complete impact this ASU will have on its consolidated financial statements and related disclosures, it expects the ASU to have a material impact on its consolidated balance sheet for recognition of lease-related assets and liabilities. In January 2018, the FASB released guidance on the accounting for tax on the global intangible low-taxed income ("GILTI") provisions of the Tax Act. The GILTI provisions impose a tax on foreign income in excess of a deemed return on tangible assets of foreign corporations. The guidance indicates that either accounting for deferred taxes related to GILTI inclusions or to treat any taxes on GILTI inclusions as period costs are both acceptable methods subject to an accounting policy election. The Company has not yet made an accounting policy election in regards to the GILTI provisions under the Tax Act. The Company will make its GILTI accounting policy election during the one-year measurement period as allowed by the SEC. No amounts have been recorded in the Company's 2017 financial statements for the impact of GILTI provisions. Recently Adopted Accounting Standards In March 2016, the FASB issued ASU 2016-09, which affects all entities that issue share-based payment awards to their employees. The amendments in this ASU cover such areas as the recognition of excess tax benefits and deficiencies, the classification of those excess tax benefits on the statement of cash flows, an accounting policy election for forfeitures and the classification of those taxes paid on the statement of cash flows. The Company adopted the provisions of this ASU on January 1, 2017 on a prospective basis and recorded an excess tax deficiency of $1.3 million as an increase in income tax expense related to share-based compensation for vested awards. Additionally, the Company made a policy election under the provisions of this ASU to account for forfeitures when they occur rather than estimating the number of awards that are expected to vest. As a result of this election, upon adoption of the guidance in this ASU, the Company recorded a $1.9 million cumulative-effect benefit to retained earnings as of the date of adoption. The Company adopted the provisions of this ASU related to changes on the Consolidated Statement of Cash Flows on a retrospective basis. Excess tax benefits and deficiencies have been classified within cash flows from operating activities and employee taxes paid for shares withheld for income taxes have been classified within cash flows from financing activities on the Consolidated Statement of Cash Flows. This resulted in increases of $44.8 million and $45.9 million to cash flows from operating activities for the years ended December 31, 2016 and 2015, respectively. This also resulted in decreases of $15.1 million and $12.7 million to cash flows from financing activities for the year ended December 31, 2015 and 2016, respectively. In October 2016, the FASB issued ASU 2016-16, which requires an entity to recognize the income tax consequences of an intra-entity transfer of an asset, other than inventory, when the transfer occurs. The Company adopted the provisions of this ASU on a modified retrospective basis on January 1, 2017, resulting in a cumulative-effect benefit to retained earnings of $26.0 million as of the date of adoption. In January 2017, the FASB issued ASU 2017-04, which simplifies how an entity is required to test goodwill for impairment by eliminating step two of the test. The Company adopted the provisions of this ASU on July 1, 2017, and recorded an impairment charge of $28.6 million during its interim goodwill impairment test for the Connected Fitness reporting unit.

Restructuring and Impairments (Tables)

12 Months Ended

Dec. 31, 2017

Restructuring and Related Activities [Abstract]

Restructuring and Related Costs

The summary of the costs incurred during the year ended December 31, 2017 in connection with the 2017 restructuring plan are as follows:



	Year Ended December 31,
(In thousands)	2017
Costs recorded in cost of goods sold:
Inventory write-offs (1)	$	5,077
Total costs recorded in cost of goods sold	5,077

Costs recorded in restructuring and impairment charges:
Goodwill impairment	28,647
Property and equipment impairment	30,677
Employee related costs	14,572
Intangible asset impairment	12,054
Contract exit costs	12,029
Other restructuring costs	26,070
Total costs recorded in restructuring and impairment charges	124,049
Total restructuring, impairment and restructuring related costs	$	129,126

Schedule of Restructuring Reserve by Type of Cost

A summary of the activity in the restructuring reserve related to the 2017 Restructuring Plan is as follows:



	Employee Related costs			Contract Exit Costs			Other Restructuring Related Costs
Balance at January 1, 2017	$	—		$	—		$	—
Additions charged to expense	14,572			12,029			13,070
Cash payments charged against reserve	(10,017		)	(9,181		)	(10,070		)
Balance at December 31, 2017	$	4,555		$	2,848		$	3,000

Property and Equipment, Net Property and Equipment, Net (Tables)

12 Months Ended

Dec. 31, 2017

Property, Plant and Equipment [Abstract]

Components of Property and Equipment

Property and equipment consisted of the following:



	December 31,
(In thousands)	2017			2016
Leasehold and tenant improvements	$	431,761		$	326,617
Furniture, fixtures and displays	204,926			168,720
Buildings	47,625			47,216
Software	232,660			151,059
Office equipment	98,802			75,196
Plant equipment	144,484			124,140
Land	83,574			83,574
Construction in progress	148,488			204,362
Other	20,438			20,383
Subtotal property and equipment	1,412,758			1,201,267
Accumulated depreciation	(526,984		)	(397,056		)
Property and equipment, net	$	885,774		$	804,211

Goodwill and Intangible Assets, Net (Tables)

12 Months Ended

Dec. 31, 2017

Goodwill and Intangible Assets Disclosure [Abstract]

Schedule of Goodwill

The following table summarizes changes in the carrying amount of the Company’s goodwill by reportable segment as of the periods indicated:



	North America		EMEA		Asia-Pacific		Latin America		Connected Fitness			Total
Balance as of December 31, 2016	$	317,323	$	99,245	$	77,586	$	42,436	$	27,001		$	563,591
Effect of currency translation adjustment	1,132		11,910		3,737		2,305		1,646			20,730
Impairment	—		—		—		—		(28,647		)	(28,647		)
Balance as of December 31, 2017	$	318,455	$	111,155	$	81,323	$	44,741	$	—		$	555,674

Summary Of Intangible Assets

The following table summarizes the Company’s intangible assets as of the periods indicated:



		December 31, 2017										December 31, 2016
(In thousands)	Useful Lives from Date of Acquisitions (in years)	Gross Carrying Amount		Accumulated Amortization			Impairment			Net Carrying Amount		Gross Carrying Amount		Accumulated Amortization			Net Carrying Amount
Intangible assets subject to amortization:
User base	10	$	48,561	$	(13,499	)	$	—		$	35,062	$	47,653	$	(8,733	)	$	38,920
Technology	5-7	19,611		(9,524		)	(10,087		)	—		19,612		(8,221		)	11,391
Customer relationships	2-3	9,527		(9,527		)	—			—		9,527		(9,527		)	—
Trade name	4-5	7,653		(5,686		)	(1,967		)	—		7,653		(4,816		)	2,837
Nutrition database	10	4,500		(1,256		)	—			3,244		4,500		(806		)	3,694
Lease-related intangible assets	1-15	3,896		(3,232		)	—			664		3,896		(3,075		)	821
Other	5-10	1,353		(892		)	—			461		1,373		(666		)	707
Total		$	95,101	$	(43,616	)	$	(12,054	)	$	39,431	$	94,214	$	(35,844	)	$	58,370
Indefinite-lived intangible assets										7,564							5,940
Intangible assets, net										$	46,995						$	64,310

Schedule of Finite-Lived Intangible Assets, Future Amortization Expense

The following is the estimated amortization expense for the Company’s intangible assets as of December 31, 2017:



(In thousands)
2018	$	5,715
2019	5,608
2020	5,536
2021	5,447
2022	5,428
2023 and thereafter	11,697
Amortization expense of intangible assets	$	39,431

Commitments And Contingencies (Tables)

12 Months Ended

Dec. 31, 2017

Commitments and Contingencies Disclosure [Abstract]

Future Minimum Lease Payments For Non-Cancelable Real Property Operating Leases

The following is a schedule of future minimum lease payments for non-cancelable real property operating leases as of December 31, 2017 as well as significant operating lease agreements entered into during the period after December 31, 2017 through the date of this report:



(In thousands)
2018	140,257
2019	139,304
2020	158,455
2021	147,094
2022	132,312
2023 and thereafter	772,047
Total future minimum lease payments	$	1,489,469

Future Minimum Payments Under Sponsorship And Other Marketing Agreements

The following is a schedule of the Company’s future minimum payments under its sponsorship and other marketing agreements as of December 31, 2017, as well as significant sponsorship and other marketing agreements entered into during the period after December 31, 2017 through the date of this report:



(In thousands)
2018	150,428
2019	135,165
2020	126,026
2021	121,710
2022	119,783
2023 and thereafter	517,736
Total future minimum sponsorship and other payments	$	1,170,848

Fair Value Measurements (Tables)

12 Months Ended

Dec. 31, 2017

Fair Value Disclosures [Abstract]

Financial Assets and (Liabilities) Measured at Fair Value

Financial assets and (liabilities) measured at fair value are set forth in the table below:



	December 31, 2017							December 31, 2016
(In thousands)	Level 1		Level 2			Level 3		Level 1		Level 2			Level 3
Derivative foreign currency contracts (see Note 8)	$	—	$	(6,818	)	$	—	$	—	$	15,238		$	—
Interest rate swap contracts (see Note 8)	—		1,088			—		—		(420		)	—
TOLI policies held by the Rabbi Trust	—		5,756			—		—		4,880			—
Deferred Compensation Plan obligations	—		(7,971		)	—		—		(7,023		)	—

Provision for Income Taxes Schedule of Income before Income Tax (Tables)

12 Months Ended

Dec. 31, 2017

Income Tax Disclosure [Abstract]

Schedule of Income before Income Tax, Domestic and Foreign

Income (loss) before income taxes is as follows:



	Year Ended December 31,
(In thousands)	2017			2016		2015
Income (loss) before income taxes:
United States	$	(131,475	)	$	251,321	$	272,739
Foreign	121,166			136,961		113,946
Total	$	(10,309	)	$	388,282	$	386,685

Schedule of Components of Income Tax Expense (Benefit)

The components of the provision for income taxes consisted of the following:



	Year Ended December 31,
(In thousands)	2017			2016			2015
Current
Federal	$	(46,931	)	$	116,637		$	102,317
State	(8,336		)	29,989			27,500
Other foreign countries	34,005			32,394			28,336
	(21,262		)	179,020			158,153
Deferred
Federal	51,447			(35,748		)	707
State	12,080			(10,658		)	(5,703		)
Other foreign countries	(4,314		)	(1,311		)	955
	59,213			(47,717		)	(4,041		)
Provision for income taxes	$	37,951		$	131,303		$	154,112

Schedule of Effective Income Tax Rate Reconciliation

A reconciliation from the U.S. statutory federal income tax rate to the effective income tax rate is as follows:



	Year Ended December 31,
	2017					2016					2015
U.S. federal statutory income tax rate	$	(3,608	)	35.0	%	$	135,899		35.0	%	$	135,340		35.0	%
State taxes, net of federal tax impact	(9,537		)	92.5		9,447			2.4		12,252			3.2
Unrecognized tax benefits	1,178			(11.4	)	4,377			1.1		12,931			3.4
Permanent tax benefits/nondeductible expenses	2,246			(21.8	)	(5,177		)	(1.3	)	8,475			2.2
Goodwill impairment	8,522			(82.7	)	—			—		—			—
Foreign rate differential	(25,563		)	248.0		(25,768		)	(6.6	)	(21,262		)	(5.5	)
Valuation allowance	29,563			(290.3	)	8,798			2.3		10,504			2.7
Impacts related to Tax Act	38,833			(376.7	)	—			—		—			—
Other	(3,683		)	39.2		3,727			0.9		(4,128		)	(1.1	)
Effective income tax rate	$	37,951		(368.2	)%	$	131,303		33.8	%	$	154,112		39.9	%

Schedule of Deferred Tax Assets and Liabilities

Deferred tax assets and liabilities consisted of the following:



	December 31,
(In thousands)	2017			2016
Deferred tax asset
Allowance for doubtful accounts and sales return reserves	$	52,745		$	53,811
Foreign net operating loss carry-forwards	34,542			26,964
Tax basis inventory adjustment	30,531			25,776
Reserves and accrued liabilities	20,500			38,819
Stock-based compensation	19,002			32,910
Deferred rent	18,735			21,168
U.S. net operating loss carryforward	13,382			3,032
Foreign tax credit carry-forwards	11,918			8,664
State tax credits, net of federal impact	8,555			7,408
Inventory obsolescence reserves	5,241			15,479
Other	4,340			3,107
Total deferred tax assets	219,491			237,138
Less: valuation allowance	(73,544		)	(37,969		)
Total net deferred tax assets	145,947			199,169

Deferred tax liability
Property, plant and equipment	(43,924		)	(45,178		)
Prepaid expenses	(18,336		)	(8,628		)
Intangible assets	—			(6,815		)
Other	(1,218		)	(2,506		)
Total deferred tax liabilities	(63,478		)	(63,127		)
Total deferred tax assets, net	$	82,469		$	136,042

Summary of Income Tax Contingencies

The following table represents a reconciliation of the Company's total unrecognized tax benefits balances, excluding interest and penalties, for the years ended December 31, 2017, 2016 and 2015.



	Year Ended December 31,
(In thousands)	2017			2016			2015
Beginning of year	$	64,359		$	42,611		$	28,353
Increases as a result of tax positions taken in a prior period	457			661			203
Decreases as a result of tax positions taken in a prior period	(40		)	—			—
Increases as a result of tax positions taken during the current period	14,580			26,482			14,382
Decreases as a result of tax positions taken during the current period	—			—			—
Decreases as a result of settlements during the current period	(13,885		)	—			—
Reductions as a result of a lapse of statute of limitations during the current period	(13,656		)	(5,395		)	(327		)
End of year	$	51,815		$	64,359		$	42,611

Earnings per Share (Tables)

12 Months Ended

Dec. 31, 2017

Earnings Per Share [Abstract]

Schedule of Reconciliation of Basic Earnings per Share to Diluted Earnings per Share

The following is a reconciliation of basic earnings per share to diluted earnings per share:



	Year Ended December 31,
(In thousands, except per share amounts)	2017			2016		2015
Numerator
Net income (loss)	$	(48,260	)	$	256,979	$	232,573
Adjustment payment to Class C capital stockholders	—			59,000		—
Net income (loss) available to all stockholders	$	(48,260	)	$	197,979	$	232,573

Denominator - Class A and B shares
Weighted average common shares outstanding	219,254			217,707		215,498
Effect of dilutive securities	—			4,237		5,370
Weighted average common shares and dilutive securities outstanding	219,254			221,944		220,868
Earnings per share Class A and B —basic	$	(0.11	)	$	0.45	$	0.54
Earnings per share Class A and B—diluted	$	(0.11	)	$	0.45	$	0.53

Denominator - Class C shares
Weighted average common shares outstanding	221,475			218,623		215,498
Effect of dilutive securities	—			4,281		5,370
Weighted average common shares and dilutive securities outstanding	221,475			222,904		220,868
Earnings (loss) per share Class C — basic	$	(0.11	)	$	0.72	$	0.54
Earnings (loss) per share Class C — diluted	$	(0.11	)	$	0.71	$	0.53

Stock-Based Compensation (Tables)

12 Months Ended

Dec. 31, 2017

Disclosure of Compensation Related Costs, Share-based Payments [Abstract]

Schedule of Share-based Payment Award, Valuation Assumptions

The fair value of each stock option granted is estimated on the date of grant using the Black-Scholes option-pricing model with the following weighted average assumptions:



	Year Ended December 31,
	2017		2016		2015
Risk-free interest rate	2.1	%	1.4	%	1.8	%
Average expected life in years	6.50		6.50		6.00
Expected volatility	39.6	%	39.5	%	44.3	%
Expected dividend yield	—	%	—	%	—	%

Summary Of Stock Options Activity

A summary of the Company’s stock options as of December 31, 2017, 2016 and 2015, and changes during the years then ended is presented below:



(In thousands, except per share amounts)	Year Ended December 31,
(In thousands, except per share amounts)	2017				2016				2015
	Number of Stock Options		Weighted Average Exercise Price		Number of Stock Options		Weighted Average Exercise Price		Number of Stock Options		Weighted Average Exercise Price
Outstanding, beginning of year	4,265		$	9.63	6,008		$	7.26	5,622		$	4.14
Granted, at fair market value	734		19.04		335		36.05		1,158		20.15
Exercised	(1,046	)	3.72		(1,763	)	3.52		(720	)	3.96
Expired	—		—		—		—		—		—
Forfeited	(171	)	17.59		(315	)	26.26		(52	)	2.27
Outstanding, end of year	3,782		$	12.71	4,265		$	9.63	6,008		$	7.26
Options exercisable, end of year	2,512		$	5.85	3,385		$	4.30	4,892		$	4.13

Stock Options Outstanding And Exercisable

The following table summarizes information about stock options outstanding and exercisable as of December 31, 2017:

(In thousands, except per share amounts)



Options Outstanding						Options Exercisable
Number of Underlying Shares	Weighted Average Exercise Price Per Share		Weighted Average Remaining Contractual Life (Years)	Total Intrinsic Value		Number of Underlying Shares	Weighted Average Exercise Price Per Share		Weighted Average Remaining Contractual Life (Years)	Total Intrinsic Value
3,782	$	12.71	4.55	$	22,679	2,512	$	5.85	2.52	$	22,553

Summary Of Restricted Stock And Restricted Stock Units

A summary of the Company’s restricted stock and restricted stock units as of December 31, 2017, 2016 and 2015, and changes during the years then ended is presented below:



	Year Ended December 31,
	2017				2016				2015
(In thousands, except per share amounts)	Number of Restricted Shares		Weighted Average Grant Date Fair Value		Number of Restricted Shares		Weighted Average Fair Value		Number of Restricted Shares		Weighted Average Fair Value
Outstanding, beginning of year	6,771		$	19.68	6,760		$	23.23	9,020		$	15.21
Granted	7,630		18.84		4,002		35.20		2,030		38.36
Forfeited	(2,290	)	28.71		(935	)	30.35		(652	)	24.29
Vested	(2,188	)	24.78		(3,056	)	16.25		(3,638	)	11.61
Outstanding, end of year	9,923		24.41		6,771		19.68		6,760		23.23

Risk Management and Derivatives (Tables)

12 Months Ended

Dec. 31, 2017

Derivative Instruments and Hedging Activities Disclosure [Abstract]

Changes in Foreign Currency Exchange Rates and Derivative Foreign Currency Forward Contracts

Included in other expense, net were the following amounts related to changes in foreign currency exchange rates and derivative foreign currency contracts:



(In thousands)	Year Ended December 31,
(In thousands)	2017			2016			2015
Unrealized foreign currency exchange rate gains (losses)	$	29,246		$	(12,627	)	$	(33,359	)
Realized foreign currency exchange rate gains (losses)	611			(6,906		)	7,643
Unrealized derivative gains (losses)	(1,217		)	729			388
Realized derivative gains (losses)	(26,537		)	15,192			16,404

Segment Data and Related Information (Tables)

12 Months Ended

Dec. 31, 2017

Segment Reporting [Abstract]

Reconciliation of Revenue from Segments to Consolidated



(In thousands)	Year Ended December 31,
(In thousands)	2017		2016			2015
Net revenues
North America	$	3,802,406	$	4,005,314		$	3,455,737
EMEA	469,997		330,584			203,109
Asia-Pacific	433,647		268,607			144,877
Latin America	181,324		141,793			106,175
Connected Fitness	89,179		80,447			53,415
Intersegment Eliminations	—		(1,410		)	—
Total net revenues	$	4,976,553	$	4,825,335		$	3,963,313

Reconciliation of Operating Profit (Loss) from Segments to Consolidated



(In thousands)	Year Ended December 31,
(In thousands)	2017			2016			2015
Operating income (loss)
North America	$	20,179		$	408,424		$	460,961
EMEA	17,976			11,420			3,122
Asia-Pacific	82,039			68,338			36,358
Latin America	(37,085		)	(33,891		)	(30,593		)
Connected Fitness	(55,266		)	(36,820		)	(61,301		)
Total operating income	27,843			417,471			408,547
Interest expense, net	(34,538		)	(26,434		)	(14,628		)
Other expense, net	(3,614		)	(2,755		)	(7,234		)
Income (loss) before income taxes	$	(10,309	)	$	388,282		$	386,685

Net Revenues by Product Category

Net revenues by product category are as follows:



(In thousands)	Year Ended December 31,
(In thousands)	2017		2016			2015
Apparel	$	3,287,121	$	3,229,142		$	2,801,062
Footwear	1,037,840		1,010,693			677,744
Accessories	445,838		406,614			346,885
Total net sales	4,770,799		4,646,449			3,825,691
Licensing revenues	116,575		99,849			84,207
Connected Fitness	89,179		80,447			53,415
Intersegment Eliminations	—		(1,410		)	—
Total net revenues	$	4,976,553	$	4,825,335		$	3,963,313

Charges incurred and expected to be incurred by segment in connection with each of the respective restructuring plans are as follows:



(In thousands)	Costs Incurred During the Year Ended December 31, 2017 (1)		Costs to be Incurred During the Year Ending December 31, 2018
Costs recorded in restructuring and impairment charges:
North America	$	63,170	$	109,000
EMEA	1,525		6,000
Asia-Pacific	38		—
Latin America	11,506		18,000
Connected Fitness	47,810		—
Total costs recorded in restructuring and impairment charges	$	124,049	$	133,000

(1) This table excludes additional non-cash charges of $5.1 million associated with the reduction of inventory outside of current liquidation channels in line with the 2017 restructuring plan.

Schedule of Revenue from External Customers and Long-Lived Assets, by Geographical Areas

Long-lived assets are primarily composed of Property and equipment, net. The Company's long-lived assets by geographic area were as follows:



(In thousands)	Year Ended December 31,
(In thousands)	2017		2016
Long-lived assets
United States	$	763,477	$	728,841
Canada	14,077		11,126
Total North America	777,554		739,967
Other foreign countries	108,220		64,244
Total long lived assets	$	885,774	$	804,211

Unaudited Quarterly Financial Data (Tables)

12 Months Ended

Dec. 31, 2017

Quarterly Financial Data [Abstract]

Selected Quarterly Financial Data



(In thousands)	Quarter Ended (unaudited)											Year Ended December 31,
(In thousands)	March 31,			June 30,			September 30,		December 31,			Year Ended December 31,
2017
Net revenues	$	1,117,331		$	1,088,245		$	1,405,615	$	1,365,362		$	4,976,553
Gross profit	505,423			498,246			645,350		589,704			2,238,723
Income (loss) from operations	7,536			(4,785		)	62,180		(37,088		)	27,843
Net income (loss)	(2,272		)	(12,308		)	54,242		(87,922		)	(48,260		)
Net income (loss) available to all stockholders	$	(2,272	)	$	(12,308	)	$	54,242	$	(87,922	)	$	(48,260	)
Basic net income (loss) per share of Class A and B common stock	$	(0.01	)	$	(0.03	)	$	0.12	$	(0.20	)	$	(0.11	)
Basic net income (loss) per share of Class C common stock	$	(0.01	)	$	(0.03	)	$	0.12	$	(0.20	)	$	(0.11	)
Diluted net income (loss) per share of Class A and B common stock	$	(0.01	)	$	(0.03	)	$	0.12	$	(0.20	)	$	(0.11	)
Diluted net income (loss) per share of Class C common stock	$	(0.01	)	$	(0.03	)	$	0.12	$	(0.20	)	$	(0.11	)

2016
Net revenues	$	1,047,702		$	1,000,783		$	1,471,573	$	1,305,277		$	4,825,335
Gross profit	480,636			477,647			698,624		583,704			2,240,611
Income from operations	34,883			19,378			199,310		163,900			417,471
Net income	19,180			6,344			128,225		103,230			256,979
Adjustment payment to Class C capital stockholders	—			59,000			—		—			59,000
Net income (loss) available to all stockholders	19,180			(52,656		)	128,225		103,230			197,979
Basic net income (loss) per share of Class A and B common stock	$	0.04		$	(0.12	)	$	0.29	$	0.24		$	0.45
Basic net income (loss) per share of Class C common stock	$	0.04		$	0.15		$	0.29	$	0.24		$	0.72
Diluted net income (loss) per share of Class A and B common stock	$	0.04		$	(0.12	)	$	0.29	$	0.23		$	0.45
Diluted net income (loss) per share of Class C common stock	$	0.04		$	0.15		$	0.29	$	0.23		$	0.71

Summary of Significant Accounting Policies (Narrative) (Detail) ¥ in Millions				3 Months Ended						12 Months Ended
	Jul. 27, 2017 USD ($)	Jun. 29, 2016 USD ($) shares	Jun. 03, 2016 USD ($)	Dec. 31, 2017 USD ($)	Sep. 30, 2017 USD ($)	Dec. 31, 2016 USD ($)	Sep. 30, 2016 USD ($)	Jun. 30, 2016 USD ($)	Mar. 31, 2016 USD ($)	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)	Dec. 31, 2017 JPY (¥)	Dec. 31, 2017 USD ($)	Jan. 01, 2017 USD ($)
Summary Of Significant Accounting Policies [Line Items]
Adjustment payment to Class C capital stockholders			$ 59,000,000
Dividends paid, cash		$ 2,900,000								$ 0	$ 2,927,000	$ 0
Interest income related to cash and cash equivalents										400,000	300,000	200,000
Allowance for doubtful accounts receivable						$ 11,300,000					11,300,000			$ 19,700,000
Capitalized interest										2,100,000	1,800,000
Property and equipment impairment										30,677,000
Goodwill impairment	$ 28,600,000			$ 0	$ 28,600,000					28,647,000
Intangible asset impairment					$ 12,100,000					12,054,000
Accrued liabilities accrued compensation and benefits						60,800,000					60,800,000			92,700,000
Accrued liabilities, accrued marketing expenses						24,700,000					24,700,000			47,000,000
Reserves for customer returns allowances markdowns and discounts										246,600,000	146,200,000
Advertising expense										565,100,000	477,500,000	417,800,000
Prepaid advertising						32,000,000					32,000,000			41,200,000
Shipping and handling costs										101,500,000	89,900,000	63,700,000
Cost method investments						11,700,000					11,700,000			12,700,000
Impact of adoption of accounting standard updates						(26,598,000)					(26,598,000)
Increase to cash flows from operating activities										75,000	(44,783,000)	(45,917,000)
Decrease to cash flows from financing activities										$ (2,781,000)	(15,098,000)	$ (12,728,000)
Retained Earnings
Summary Of Significant Accounting Policies [Line Items]
Impact of adoption of accounting standard updates						(23,932,000)					(23,932,000)
Accounting Standards Update 2016-09 \| Retained Earnings
Summary Of Significant Accounting Policies [Line Items]
Impact of adoption of accounting standard updates															$ 1,300,000
Cumulative-effect benefit to retained earnings															1,900,000
Accounting Standards Update 2016-16 \| Retained Earnings
Summary Of Significant Accounting Policies [Line Items]
Cumulative-effect benefit to retained earnings															$ 26,000,000
Senior Notes
Summary Of Significant Accounting Policies [Line Items]
Fair value of senior notes						568,100,000					$ 568,100,000			526,300,000
Dome Corporation
Summary Of Significant Accounting Policies [Line Items]
Ownership percentage, cost method investment										19.50%
Dome Corporation \| Japan, Yen
Summary Of Significant Accounting Policies [Line Items]
Cost method investments \| ¥													¥ 1,140.0
Dome Corporation \| United States of America, Dollars
Summary Of Significant Accounting Policies [Line Items]
Cost method investments														$ 15,500,000
Furniture Office Equipment And Software \| Minimum
Summary Of Significant Accounting Policies [Line Items]
Property and equipment, useful life										3 years
Furniture Office Equipment And Software \| Maximum
Summary Of Significant Accounting Policies [Line Items]
Property and equipment, useful life										10 years
Site Improvement Buildings And Building Equipment \| Minimum
Summary Of Significant Accounting Policies [Line Items]
Property and equipment, useful life										10 years
Site Improvement Buildings And Building Equipment \| Maximum
Summary Of Significant Accounting Policies [Line Items]
Property and equipment, useful life										35 years
Fixtures And Displays
Summary Of Significant Accounting Policies [Line Items]
Property and equipment, useful life										3 years
Customer Concentration Risk \| Accounts Receivable \| Largest customer
Summary Of Significant Accounting Policies [Line Items]
Concentration risk percentage										12.00%	16.00%
Customer Concentration Risk \| Sales Revenue, Goods, Net \| Largest customer
Summary Of Significant Accounting Policies [Line Items]
Concentration risk percentage											10.00%	12.00%
Class C Common Stock
Summary Of Significant Accounting Policies [Line Items]
Adjustment payment to Class C capital stockholders						$ 0	$ 0	$ 59,000,000	$ 0	$ 0	$ 59,000,000	$ 0
Dividends distributed (in shares) \| shares		1,470,256

Restructuring and Impairments - Narrative (Details) - USD ($)		3 Months Ended		12 Months Ended
	Jul. 27, 2017	Dec. 31, 2017	Sep. 30, 2017	Dec. 31, 2017	Feb. 09, 2018
Restructuring Cost and Reserve [Line Items]
Additions charged to expense	$ 100,400,000			$ 13,070,000
Goodwill impairment	$ 28,600,000	$ 0	$ 28,600,000	28,647,000
Property and equipment impairment				30,677,000
Intangible asset impairment			$ 12,100,000	$ 12,054,000
2018 Plan \| Minimum \| Subsequent Event
Restructuring Cost and Reserve [Line Items]
Restructuring and related charges expected, cash					$ 110,000,000
2018 Plan \| Maximum \| Subsequent Event
Restructuring Cost and Reserve [Line Items]
Restructuring and related charges expected, cash					130,000,000
2018 Plan \| Maximum \| Subsequent Event \| Facility Closing, Lease and Contract Termination, and Other Restructuring
Restructuring Cost and Reserve [Line Items]
Restructuring and related charges expected, cash					105,000,000
2018 Plan \| Maximum \| Subsequent Event \| Facility Closing and Lease Termination
Restructuring Cost and Reserve [Line Items]
Restructuring and related charges expected, cash					55,000,000
2018 Plan \| Maximum \| Subsequent Event \| Contract Termination and Other Restructuring
Restructuring Cost and Reserve [Line Items]
Restructuring and related charges expected, cash					50,000,000
2018 Plan \| Maximum \| Subsequent Event \| Inventory and Intangible and Other Asset Impairments
Restructuring Cost and Reserve [Line Items]
Restructuring and related charges expected, cash					25,000,000
2018 Plan \| Maximum \| Subsequent Event \| Inventory Related
Restructuring Cost and Reserve [Line Items]
Restructuring and related charges expected, cash					10,000,000
2018 Plan \| Maximum \| Subsequent Event \| Intangible and Other Asset Impairment
Restructuring Cost and Reserve [Line Items]
Restructuring and related charges expected, cash					$ 15,000,000

Restructuring and Impairments - Summary of Cost Incurred (Details) - USD ($)		3 Months Ended		12 Months Ended
	Jul. 27, 2017	Dec. 31, 2017	Sep. 30, 2017	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Restructuring and Related Activities [Abstract]
Inventory write-offs				$ 5,077,000
Goodwill impairment	$ 28,600,000	$ 0	$ 28,600,000	28,647,000
Property and equipment impairment				30,677,000
Employee related costs				14,572,000
Intangible asset impairment			$ 12,100,000	12,054,000
Contract exit costs				12,029,000
Other restructuring costs				26,070,000
Total costs recorded in restructuring and impairment charges				124,049,000	$ 0	$ 0
Total restructuring, impairment and restructuring related costs				$ 129,126,000

Restructuring and Impairments - Activity in the Restructuring Reserve (Details) - USD ($) $ in Thousands		12 Months Ended
	Jul. 27, 2017	Dec. 31, 2017
Restructuring Cost and Reserve [Line Items]
Balance at January 1, 2017		$ 0
Additions charged to expense	$ 100,400	13,070
Cash payments charged against reserve		(10,070)
Balance at December 31, 2017		3,000
Employee Related costs
Restructuring Cost and Reserve [Line Items]
Balance at January 1, 2017		0
Additions charged to expense		14,572
Cash payments charged against reserve		(10,017)
Balance at December 31, 2017		4,555
Contract Exit Costs
Restructuring Cost and Reserve [Line Items]
Balance at January 1, 2017		0
Additions charged to expense		12,029
Cash payments charged against reserve		(9,181)
Balance at December 31, 2017		$ 2,848

Property and Equipment, Net - Components of Property And Equipment (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Property, Plant and Equipment [Line Items]
Property and equipment	$ 1,412,758	$ 1,201,267
Accumulated depreciation	(526,984)	(397,056)
Property and equipment, net	885,774	804,211
Leasehold and tenant improvements
Property, Plant and Equipment [Line Items]
Property and equipment	431,761	326,617
Furniture, fixtures and displays
Property, Plant and Equipment [Line Items]
Property and equipment	204,926	168,720
Buildings
Property, Plant and Equipment [Line Items]
Property and equipment	47,625	47,216
Software
Property, Plant and Equipment [Line Items]
Property and equipment	232,660	151,059
Office equipment
Property, Plant and Equipment [Line Items]
Property and equipment	98,802	75,196
Plant equipment
Property, Plant and Equipment [Line Items]
Property and equipment	144,484	124,140
Land
Property, Plant and Equipment [Line Items]
Property and equipment	83,574	83,574
Construction in progress
Property, Plant and Equipment [Line Items]
Property and equipment	148,488	204,362
Other
Property, Plant and Equipment [Line Items]
Property and equipment	$ 20,438	$ 20,383

Property and Equipment, Net - Narrative (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Property, Plant and Equipment [Line Items]
Depreciation expense	$ 173,747	$ 144,770	$ 100,940
Property And Equipment [Member]
Property, Plant and Equipment [Line Items]
Depreciation expense	$ 164,300	$ 130,700	$ 86,300

Goodwill and Intangible Assets, Net - Schedule of Goodwill (Details) - USD ($)		3 Months Ended		12 Months Ended
	Jul. 27, 2017	Dec. 31, 2017	Sep. 30, 2017	Dec. 31, 2017
Goodwill [Roll Forward]
Balance as of December 31, 2016				$ 563,591,000
Effect of currency translation adjustment				20,730,000
Impairment	$ (28,600,000)	$ 0	$ (28,600,000)	(28,647,000)
Balance as of December 31, 2017		555,674,000		555,674,000
North America
Goodwill [Roll Forward]
Balance as of December 31, 2016				317,323,000
Effect of currency translation adjustment				1,132,000
Impairment				0
Balance as of December 31, 2017		318,455,000		318,455,000
EMEA
Goodwill [Roll Forward]
Balance as of December 31, 2016				99,245,000
Effect of currency translation adjustment				11,910,000
Impairment				0
Balance as of December 31, 2017		111,155,000		111,155,000
Asia-Pacific
Goodwill [Roll Forward]
Balance as of December 31, 2016				77,586,000
Effect of currency translation adjustment				3,737,000
Impairment				0
Balance as of December 31, 2017		81,323,000		81,323,000
Latin America
Goodwill [Roll Forward]
Balance as of December 31, 2016				42,436,000
Effect of currency translation adjustment				2,305,000
Impairment				0
Balance as of December 31, 2017		44,741,000		44,741,000
Connected Fitness
Goodwill [Roll Forward]
Balance as of December 31, 2016				27,001,000
Effect of currency translation adjustment				1,646,000
Impairment				(28,647,000)
Balance as of December 31, 2017		$ 0		$ 0

Goodwill and Intangible Assets, Net - Summary of Intangible Assets (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Sep. 30, 2017	Dec. 31, 2017	Dec. 31, 2016
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount		$ 95,101	$ 94,214
Accumulated Amortization		(43,616)	(35,844)
Impairment	$ (12,100)	(12,054)
Net Carrying Amount		39,431	58,370
Indefinite-lived intangible assets		7,564	5,940
Intangible assets, net		$ 46,995	64,310
User base
Finite-Lived Intangible Assets [Line Items]
Useful Lives from Date of Acquisitions (in years)		10 years
Gross Carrying Amount		$ 48,561	47,653
Accumulated Amortization		(13,499)	(8,733)
Impairment		0
Net Carrying Amount		35,062	38,920
Technology
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount		19,611	19,612
Accumulated Amortization		(9,524)	(8,221)
Impairment		(10,087)
Net Carrying Amount		0	11,391
Customer relationships
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount		9,527	9,527
Accumulated Amortization		(9,527)	(9,527)
Impairment		0
Net Carrying Amount		0	0
Trade name
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount		7,653	7,653
Accumulated Amortization		(5,686)	(4,816)
Impairment		(1,967)
Net Carrying Amount		$ 0	2,837
Nutrition database
Finite-Lived Intangible Assets [Line Items]
Useful Lives from Date of Acquisitions (in years)		10 years
Gross Carrying Amount		$ 4,500	4,500
Accumulated Amortization		(1,256)	(806)
Impairment		0
Net Carrying Amount		3,244	3,694
Lease-related intangible assets
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount		3,896	3,896
Accumulated Amortization		(3,232)	(3,075)
Impairment		0
Net Carrying Amount		664	821
Other
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount		1,353	1,373
Accumulated Amortization		(892)	(666)
Impairment		0
Net Carrying Amount		$ 461	$ 707
Minimum \| Technology
Finite-Lived Intangible Assets [Line Items]
Useful Lives from Date of Acquisitions (in years)		5 years
Minimum \| Customer relationships
Finite-Lived Intangible Assets [Line Items]
Useful Lives from Date of Acquisitions (in years)		2 years
Minimum \| Trade name
Finite-Lived Intangible Assets [Line Items]
Useful Lives from Date of Acquisitions (in years)		4 years
Minimum \| Lease-related intangible assets
Finite-Lived Intangible Assets [Line Items]
Useful Lives from Date of Acquisitions (in years)		1 year
Minimum \| Other
Finite-Lived Intangible Assets [Line Items]
Useful Lives from Date of Acquisitions (in years)		5 years
Maximum \| Technology
Finite-Lived Intangible Assets [Line Items]
Useful Lives from Date of Acquisitions (in years)		7 years
Maximum \| Customer relationships
Finite-Lived Intangible Assets [Line Items]
Useful Lives from Date of Acquisitions (in years)		3 years
Maximum \| Trade name
Finite-Lived Intangible Assets [Line Items]
Useful Lives from Date of Acquisitions (in years)		5 years
Maximum \| Lease-related intangible assets
Finite-Lived Intangible Assets [Line Items]
Useful Lives from Date of Acquisitions (in years)		15 years
Maximum \| Other
Finite-Lived Intangible Assets [Line Items]
Useful Lives from Date of Acquisitions (in years)		10 years

Goodwill and Intangible Assets, Net - Estimated Future Amortization Expense (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Goodwill and Intangible Assets Disclosure [Abstract]
2018	$ 5,715
2019	5,608
2020	5,536
2021	5,447
2022	5,428
2023 and thereafter	11,697
Amortization expense of intangible assets	$ 39,431	$ 58,370

Credit Facility and Long Term Debt - Additional Information (Detail)	1 Months Ended		3 Months Ended			12 Months Ended
	Jun. 30, 2015	Dec. 31, 2012 USD ($) Rate	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Dec. 31, 2017 USD ($) Rate	Dec. 31, 2016 USD ($) Rate	Dec. 31, 2015 USD ($)	Jun. 30, 2016 USD ($) Rate
Debt Disclosure [Line Items]
Revolving credit facility, current						$ 125,000,000	$ 0
Letters of credit outstanding						$ 4,500,000
Commitment fee as percentage of the committed line amount less outstanding borrowings and letters of credit						0.175%
Interest expense, net						$ (34,538,000)	(26,434,000)	$ (14,628,000)
Amortization of deferred financing costs						$ 1,300,000	$ 1,200,000	$ 800,000
LIBOR Rate
Debt Disclosure [Line Items]
Interest rate margin minimum						1.00%
Interest rate margin, maximum						1.25%
Prime Rate
Debt Disclosure [Line Items]
Interest rate margin minimum						0.00%
Interest rate margin, maximum						0.25%
Debt
Debt Disclosure [Line Items]
Covenant terms						3.25
EBITDA
Debt Disclosure [Line Items]
Covenant terms						1.00
EBITDA
Debt Disclosure [Line Items]
Covenant terms						3.50
Interest Expense
Debt Disclosure [Line Items]
Covenant terms						1.00
Letter of Credit
Debt Disclosure [Line Items]
Credit facility maximum borrowing capacity						$ 50,000,000.0
Revolving Credit Facility
Debt Disclosure [Line Items]
Credit facility maximum borrowing capacity						1,250,000,000.00
Remaining borrowing capacity						$ 300,000,000.0
Debt instrument, term		1 year
Covenant terms, minimum EBITDA						3.5
Covenant terms, minimum indebtedness to EBITDA						3.25
Financing costs						$ 3,900,000
Revolving Credit Facility \| Forecast
Debt Disclosure [Line Items]
Maximum trailing four-quarter leverage ratio			3.25	4.00	3.75
Term Loan Facility
Debt Disclosure [Line Items]
Long term debt agreements principal outstanding						$ 161,300,000
Weighted Average Interest Rate \| Rate						2.20%	1.60%
Senior Notes \| 3.250% Senior Notes
Debt Disclosure [Line Items]
Financing costs									$ 5,300,000
Senior Notes									$ 600,000,000.0
Stated percentage rate \| Rate									3.25%
Senior Notes \| 3.250% Senior Notes \| Prior to March 15, 2026
Debt Disclosure [Line Items]
Redemption price percentage	100.00%
Senior Notes \| 3.250% Senior Notes \| On or After March 15, 2026
Debt Disclosure [Line Items]
Redemption price percentage	100.00%
Secured Debt
Debt Disclosure [Line Items]
Debt instrument, term		7 years
Weighted Average Interest Rate \| Rate						2.50%	2.00%
Secured Debt		$ 50,000,000.0				$ 40,000,000	$ 42,000,000
Secured Debt \| LIBOR Rate
Debt Disclosure [Line Items]
Basis spread on variable rate \| Rate		1.50%

Credit Facility and Long Term Debt - Scheduled Maturities Of Long Term Debt (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Debt Disclosure [Abstract]
2018	$ 27,000
2019	63,000
2020	25,000
2021	86,250
2022	0
2023 and thereafter	600,000
Total scheduled maturities of long term debt	801,250
Current maturities of long term debt	$ 27,000	$ 27,000

Commitments And Contingencies (Narrative) (Details) $ in Millions	12 Months Ended
	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)	Mar. 23, 2017 case
Commitments and Contingencies Disclosure [Abstract]
Rent expense included in selling, general and administrative expense	$ 141.2	$ 109.0	$ 83.0
Contingent rent expense	$ 15.5	$ 13.0	$ 11.0
Consolidated Action \| Pending Litigation
Loss Contingencies [Line Items]
Number of cases previously filed \| case				3

- Definition

The increases or decreases in lease payments that result from changes occurring after the inception of the lease in the factors (other than the passage of time) on which lease payments are based, except that any escalation of minimum lease payments relating to increases in construction or acquisition cost of the leased property or for increases in some measure of cost or value during the construction or preconstruction period, are excluded from contingent rentals. Contingent rentals also may include amounts for which the triggering events have not yet occurred or the specified targets for which have not yet been achieved (such as sales based percentage rent), but which events are considered probable of occurring or which specified targets are considered probable of being achieved.

+ References + Details

Commitments And Contingencies (Future Minimum Lease Payments For Non-Cancelable Real Property Operating Leases) (Details) $ in Thousands	Dec. 31, 2017 USD ($)
Operating Leased Assets
2018	$ 140,257
2019	139,304
2020	158,455
2021	147,094
2022	132,312
2023 and thereafter	772,047
Total future minimum lease payments	$ 1,489,469

Commitments And Contingencies (Future Minimum Payments Under Sponsorship And Other Marketing Agreements) (Details) $ in Thousands	Dec. 31, 2017 USD ($)
Schedule of Future Minimum Payments on Sponsorship and Other Marketing Agreements [Line Items]
2018	$ 150,428
2019	135,165
2020	126,026
2021	121,710
2022	119,783
2023 and thereafter	517,736
Total future minimum sponsorship and other payments	$ 1,170,848

Stockholders' Equity (Details)	12 Months Ended
Stockholders' Equity (Details)	Dec. 31, 2017 vote $ / shares shares	Dec. 31, 2016 $ / shares shares	Jun. 30, 2015 $ / shares shares
Class A Common Stock
Class of Stock [Line Items]
Shares authorized (in shares) \| shares	400,000,000	400,000,000
Par value per share (USD Per Share) \| $ / shares	$ 0.0003	$ 0.0003
Number of votes per share \| vote	1
Class B Convertible Common Stock
Class of Stock [Line Items]
Shares authorized (in shares) \| shares	34,450,000	34,450,000
Par value per share (USD Per Share) \| $ / shares	$ 0.0003	$ 0.0003
Number of votes per share \| vote	10
Conversion ratio	1
Class A Common Stock And Class B Convertible Common Stock \| Minimum
Class of Stock [Line Items]
Beneficial ownership percentage of CEO	15.00%
Class C Common Stock
Class of Stock [Line Items]
Shares authorized (in shares) \| shares	400,000,000	400,000,000	400,000,000
Par value per share (USD Per Share) \| $ / shares	$ 0.0003	$ 0.0003	$ 0.0003

Fair Value Measurements (Financial Assets And (Liabilities) Measured At Fair Value) (Detail) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Senior Notes
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of senior notes	$ 526,300	$ 568,100
Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative foreign currency contracts (see Note 8)	0	0
TOLI policies held by the Rabbi Trust	0	0
Deferred Compensation Plan obligations	0	0
Level 1 \| Interest rate swap contracts
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Interest rate swap contracts (see Note 8)	0	0
Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative foreign currency contracts (see Note 8)	(6,818)	15,238
TOLI policies held by the Rabbi Trust	5,756	4,880
Deferred Compensation Plan obligations	(7,971)	(7,023)
Level 2 \| Interest rate swap contracts
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Interest rate swap contracts (see Note 8)	1,088	(420)
Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative foreign currency contracts (see Note 8)	0	0
TOLI policies held by the Rabbi Trust	0	0
Deferred Compensation Plan obligations	0	0
Level 3 \| Interest rate swap contracts
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Interest rate swap contracts (see Note 8)	$ 0	$ 0

Provision for Income Taxes - Narrative (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Tax Contingency [Line Items]
Provisional income tax expense (benefit)	$ 24,900
Change in tax rate, deferred tax asset, provisional income tax expense (benefit)	24,900
Transition tax for accumulated foreign earnings, provisional income tax expense (benefit)	13,900
Deferred tax assets, valuation allowance	73,544	$ 37,969
Foreign net operating loss carry-forwards	34,542	26,964
U.S. net operating loss carryforward	13,382	3,032
Deferred tax assets associated with foreign tax credits	11,918	8,664
State tax credits, net of federal impact	8,555	7,408
Cash and cash equivalents held by foreign subsidiaries	158,700
Undistributed earnings	488,400
Unrecognized tax benefits including interest and penalties	55,300	70,400
Unrecognized tax benefits excluding interest and penalties that would impact the effective tax rate if recognized	46,200
Accrual of interest and penalties	3,500	6,100
Unrecognized tax benefits, income tax penalties and interest accrued	1,600	$ 3,100	$ 1,700
Foreign Tax Authority
Income Tax Contingency [Line Items]
Operating loss carryforwards	116,000
State and Local Jurisdiction
Income Tax Contingency [Line Items]
Operating loss carryforwards	$ 207,500
State and Local Jurisdiction \| Minimum
Income Tax Contingency [Line Items]
Operating loss carryforwards, expiration period	3 years
Tax credit carryforward, expiration period	5 years
State and Local Jurisdiction \| Maximum
Income Tax Contingency [Line Items]
Operating loss carryforwards, expiration period	20 years
Tax credit carryforward, expiration period	20 years
Certain State
Income Tax Contingency [Line Items]
Deferred tax assets, valuation allowance	$ 15,900
Operating Loss Carryforward, Foreign
Income Tax Contingency [Line Items]
Deferred tax assets, valuation allowance	32,800
Operating Loss Carryforward, State and Local
Income Tax Contingency [Line Items]
Deferred tax assets, valuation allowance	11,700
Tax Credit Carryforwards, Foreign
Income Tax Contingency [Line Items]
Deferred tax assets, valuation allowance	9,900
Tax Credit Carryforwards, State Tax Credits Net Of Federal Tax Impact
Income Tax Contingency [Line Items]
Deferred tax assets, valuation allowance	$ 3,200

Provision for Income Taxes - Income (Loss) Before Income Taxes (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Tax Disclosure [Abstract]
United States	$ (131,475)	$ 251,321	$ 272,739
Foreign	121,166	136,961	113,946
Income (loss) before income taxes	$ (10,309)	$ 388,282	$ 386,685

Provision for Income Taxes - Components Of The Provision For Income Taxes (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Current
Federal	$ (46,931)	$ 116,637	$ 102,317
State	(8,336)	29,989	27,500
Other foreign countries	34,005	32,394	28,336
Provision for income taxes, Current	(21,262)	179,020	158,153
Deferred
Federal	51,447	(35,748)	707
State	12,080	(10,658)	(5,703)
Other foreign countries	(4,314)	(1,311)	955
Provision for income taxes, Deferred	59,213	(47,717)	(4,041)
Provision for income taxes	$ 37,951	$ 131,303	$ 154,112

Provision for Income Taxes - Reconciliation From The U.S. Statutory Federal Income Tax Rate To Effective Income Tax Rate (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Effective Income Tax Rate Reconciliation, Amount [Abstract]
U.S. federal statutory income tax rate	$ (3,608)	$ 135,899	$ 135,340
State taxes, net of federal tax impact	(9,537)	9,447	12,252
Unrecognized tax benefits	1,178	4,377	12,931
Permanent tax benefits/nondeductible expenses	2,246	(5,177)	8,475
Goodwill impairment	8,522	0	0
Foreign rate differential	(25,563)	(25,768)	(21,262)
Valuation allowance	29,563	8,798	10,504
Impacts related to Tax Act	38,833	0	0
Other	(3,683)	3,727	(4,128)
Provision for income taxes	$ 37,951	$ 131,303	$ 154,112
Effective Income Tax Rate Reconciliation, Percent [Abstract]
U.S. federal statutory income tax rate	35.00%	35.00%	35.00%
State taxes, net of federal tax impact	92.50%	2.40%	3.20%
Unrecognized tax benefits	(11.40%)	1.10%	3.40%
Permanent tax benefits/nondeductible expenses	(21.80%)	(1.30%)	2.20%
Goodwill impairment	(82.70%)	0.00%	0.00%
Foreign rate differential	248.00%	(6.60%)	(5.50%)
Valuation allowance	(290.30%)	2.30%	2.70%
Impacts related to Tax Act	(376.70%)	0.00%	0.00%
Other	39.20%	0.90%	(1.10%)
Effective income tax rate	(368.20%)	33.80%	39.90%

Provision for Income Taxes - Deferred Tax Assets And Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Deferred tax asset
Allowance for doubtful accounts and sales return reserves	$ 52,745	$ 53,811
Foreign net operating loss carry-forwards	34,542	26,964
Tax basis inventory adjustment	30,531	25,776
Reserves and accrued liabilities	20,500	38,819
Stock-based compensation	19,002	32,910
Deferred rent	18,735	21,168
U.S. net operating loss carryforward	13,382	3,032
Foreign tax credit carry-forwards	11,918	8,664
State tax credits, net of federal impact	8,555	7,408
Inventory obsolescence reserves	5,241	15,479
Other	4,340	3,107
Total deferred tax assets	219,491	237,138
Less: valuation allowance	(73,544)	(37,969)
Total net deferred tax assets	145,947	199,169
Deferred tax liability
Prepaid expenses	(43,924)	(45,178)
Prepaid expenses	18,336	8,628
Intangible assets	0	(6,815)
Other	(1,218)	(2,506)
Total deferred tax liabilities	(63,478)	(63,127)
Total deferred tax assets, net	$ 82,469	$ 136,042

Provision for Income Taxes - Unrecognized Tax Benefits Balances (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Beginning of year	$ 64,359	$ 42,611	$ 28,353
Increases as a result of tax positions taken in a prior period	457	661	203
Decreases as a result of tax positions taken in a prior period	(40)	0	0
Increases as a result of tax positions taken during the current period	14,580	26,482	14,382
Decreases as a result of tax positions taken during the current period	0	0	0
Decreases as a result of settlements during the current period	(13,885)	0	0
Reductions as a result of a lapse of statute of limitations during the current period	(13,656)	(5,395)	(327)
End of year	$ 51,815	$ 64,359	$ 42,611

Earnings Per Share (Schedule Of Reconciliation Of Basic Earnings Per Share To Diluted Earnings Per Share) (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands		3 Months Ended								12 Months Ended
	Jun. 03, 2016	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Earnings Per Share, Diluted, by Common Class, Including Two Class Method [Line Items]
Net income (loss)		$ (87,922)	$ 54,242	$ (12,308)	$ (2,272)	$ 103,230	$ 128,225	$ 6,344	$ 19,180	$ (48,260)	$ 256,979	$ 232,573
Adjustment payment to Class C capital stockholders	$ 59,000
Net income (loss) available to all stockholders		$ (87,922)	$ 54,242	$ (12,308)	$ (2,272)	$ 103,230	$ 128,225	$ (52,656)	$ 19,180	$ (48,260)	$ 197,979	$ 232,573
Class A Common Stock And Class B Convertible Common Stock
Earnings Per Share, Diluted, by Common Class, Including Two Class Method [Line Items]
Weighted average common shares outstanding (in shares)										219,254	217,707	215,498
Effect of dilutive securities (in shares)										0	4,237	5,370
Weighted average common shares and dilutive securities outstanding (in shares)										219,254	221,944	220,868
Earnings (loss) per share - basic (USD Per Share)		$ (0.20)	$ 0.12	$ (0.03)	$ (0.01)	$ 0.24	$ 0.29	$ (0.12)	$ 0.04	$ (0.11)	$ 0.45	$ 0.54
Earnings (loss) per share - diluted (USD Per Share)		(0.20)	0.12	(0.03)	(0.01)	$ 0.23	$ 0.29	$ (0.12)	$ 0.04	$ (0.11)	$ 0.45	$ 0.53
Class C Common Stock
Earnings Per Share, Diluted, by Common Class, Including Two Class Method [Line Items]
Adjustment payment to Class C capital stockholders						$ 0	$ 0	$ 59,000	$ 0	$ 0	$ 59,000	$ 0
Weighted average common shares outstanding (in shares)										221,475	218,623	215,498
Effect of dilutive securities (in shares)										0	4,281	5,370
Weighted average common shares and dilutive securities outstanding (in shares)										221,475	222,904	220,868
Earnings (loss) per share - basic (USD Per Share)		(0.20)	0.12	(0.03)	(0.01)	$ 0.24	$ 0.29	$ 0.15	$ 0.04	$ (0.11)	$ 0.72	$ 0.54
Earnings (loss) per share - diluted (USD Per Share)		$ (0.20)	$ 0.12	$ (0.03)	$ (0.01)	$ 0.23	$ 0.29	$ 0.15	$ 0.04	$ (0.11)	$ 0.71	$ 0.53

Earnings Per Share (Narrative) (Detail) - shares	12 Months Ended
Earnings Per Share (Narrative) (Detail) - shares	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive shares excluded from the computation of diluted earnings per share (in shares)	256,000	114,000	770,000
Class C Common Stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive shares excluded from the computation of diluted earnings per share (in shares)	4,700,000	691,600	770,000

Stock-Based Compensation - Stock Compensation Plans Narrative (Details) - USD ($) $ in Thousands, shares in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation	$ 39,932	$ 46,149	$ 60,376
Unrecognized compensation expense	$ 87,700
Unrecognized compensation expense, weighted average period	3 years 2 months 12 days
2005 Plan \| Class A Common Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares available for future grants (in shares)	7.9
2005 Plan \| Class C Common Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares available for future grants (in shares)	15.5

Stock-Based Compensation - ESPP, Non-Employee Director Compensation Plan and DSU Plan Narrative (Details) - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
ESPP
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Discount from market value	15.00%
Shares purchased under the ESPP (in shares)	563,900	290,800	103,300
ESPP \| Class A Common Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares available for future grants (in shares)	2,700,000
ESPP \| Class C Common Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares available for future grants (in shares)	1,200,000
Director Compensation Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Value of stock awards on grant date	$ 100,000
Percentage vested on date of next annual stockholders' meeting following grant date	100.00%
Director Compensation Plan \| Tranche 1
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting rights percentage	33.33%
Director Compensation Plan \| Tranche 2
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting rights percentage	33.33%
Director Compensation Plan \| Tranche 3
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting rights percentage	33.33%
2005 Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Value of stock awards on grant date	$ 150,000
Percentage vested on date of next annual stockholders' meeting following grant date	100.00%
2005 Plan \| Class A Common Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares available for future grants (in shares)	7,900,000
2005 Plan \| Class C Common Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares available for future grants (in shares)	15,500,000

Stock-Based Compensation - Stock Options Narrative (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted average grant date fair value (USD Per Share)	$ 19.04	$ 14.87	$ 27.21
Intrinsic value of stock options	$ 16.3	$ 63.9	$ 27.5
Certain Executives and Key Employees \| 2005 Plan \| Performance Based Stock Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted average grant date fair value (USD Per Share)	$ 19.04	$ 14.87
Options, grants in period (in shares)	0.5	0.3

Stock-Based Compensation - Schedule of Share-based Payment Award, Valuation Assumptions (Details)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Share-based Compensation, Allocation and Classification in Financial Statements [Abstract]
Risk-free interest rate	2.10%	1.40%	1.80%
Average expected life in years	6 years 6 months	6 years 6 months	5 years 11 months 29 days
Expected volatility	39.60%	39.50%	44.30%
Expected dividend yield	0.00%	0.00%	0.00%

Stock-Based Compensation - Summary Of Stock Options Activity (Details) - $ / shares shares in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Number of Stock Options
Outstanding, beginning of year (in shares)	4,265	6,008	5,622
Granted, at fair market value (in shares)	734	335	1,158
Exercised (in shares)	(1,046)	(1,763)	(720)
Expired (in shares)	0	0	0
Forfeited (in shares)	(171)	(315)	(52)
Outstanding, end of year (in shares)	3,782	4,265	6,008
Options exercisable, end of year (in shares)	2,512	3,385	4,892
Weighted Average Exercise Price
Outstanding, beginning of year (USD Per Share)	$ 9.63	$ 7.26	$ 4.14
Granted, at fair market value (USD Per Share)	19.04	36.05	20.15
Exercised (USD Per Share)	3.72	3.52	3.96
Expired (USD Per Share)	0.00	0.00	0.00
Forfeited (USD Per Share)	17.59	26.26	2.27
Outstanding, end of year (USD Per Share)	12.71	9.63	7.26
Options exercisable, end of year (USD Per Share)	$ 5.85	$ 4.30	$ 4.13

Stock-Based Compensation - Stock Options Outstanding And Exercisable (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Options Outstanding
Number of Underlying Shares (in shares)	3,782	4,265	6,008	5,622
Weighted Average Exercise Price Per Share (USD Per Share)	$ 12.71	$ 9.63	$ 7.26	$ 4.14
Weighted Average Remaining Contractual Life (Years)	4 years 6 months 17 days
Total Intrinsic Value	$ 22,679
Options Exercisable
Number of Underlying Shares (in shares)	2,512	3,385	4,892
Weighted Average Exercise Price Per Share (USD Per Share)	$ 5.85	$ 4.30	$ 4.13
Weighted Average Remaining Contractual Life (Years)	2 years 6 months 8 days
Total Intrinsic Value	$ 22,553

Stock-Based Compensation - Summary Of Restricted Stock And Restricted Stock Units (Details) - Restricted Stock and Restricted Stock Units - $ / shares shares in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Number of Restricted Shares
Outstanding, beginning of year (in shares)	6,771	6,760	9,020
Granted (in shares)	7,630	4,002	2,030
Forfeited (in shares)	(2,290)	(935)	(652)
Vested (in shares)	(2,188)	(3,056)	(3,638)
Outstanding, end of year (in shares)	9,923	6,771	6,760
Weighted Average Grant Date Fair Value
Outstanding, beginning of year (USD Per Share)	$ 19.68	$ 23.23	$ 15.21
Granted (USD Per Share)	18.84	35.20	38.36
Forfeited (USD Per Share)	28.71	30.35	24.29
Vested (USD Per Share)	24.78	16.25	11.61
Outstanding, end of year (USD Per Share)	$ 24.41	$ 19.68	$ 23.23

Stock-Based Compensation - Restricted Stock and Restricted Stock Units Narrative (Details) - 2005 Plan - Certain Executives and Key Employees - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended			12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Sep. 30, 2015	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation expense (reversal), cumulative adjustment			$ 10.0			$ 33.2
Performance Based Restricted Stock Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Performance-based restricted stock units awarded (in shares)				1.9	2.5	1.7
Weighted average grant date fair value (USD Per Share)				$ 18.76	$ 35.71	$ 37.87
Additional stock based compensation that would have been recorded if operating income targets had been deemed probable				$ 5.7
Performance-Based Restricted Stock Units Granted in 2017
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation expense (reversal), cumulative adjustment	$ (4.2)
Performance-Based Awards Granted in 2015
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation expense (reversal), cumulative adjustment		$ (3.6)
Performance-Based Awards Granted in 2016
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation expense (reversal), cumulative adjustment		$ (8.0)

Stock-Based Compensation - Warrants Narrative (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2006	Dec. 31, 2017
Class A Share and Class C Share
Class of Warrant or Right [Line Items]
Warrants exercised (in warrants)		0
Warrant
Class of Warrant or Right [Line Items]
Term of warrants issued	12 years
Class A Common Stock \| Warrant
Class of Warrant or Right [Line Items]
Exercise price (USD Per Share)	$ 4.66
Class A Common Stock \| 2005 Plan
Class of Warrant or Right [Line Items]
Warrants outstanding	$ 1,920
Class C Common Stock \| Warrant
Class of Warrant or Right [Line Items]
Exercise price (USD Per Share)	$ 4.59
Class C Common Stock \| 2005 Plan
Class of Warrant or Right [Line Items]
Warrants outstanding	$ 1,930

Other Employee Benefits (Details) - USD ($) $ in Thousands	12 Months Ended
Other Employee Benefits (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Defined Benefit Plan Disclosure [Line Items]
401(k) contribution matching expense	$ 7,400	$ 9,000	$ 7,000
Level 2
Defined Benefit Plan Disclosure [Line Items]
Deferred compensation plan obligations	7,971	7,023
TOLI policies held by the Rabbi Trust	$ 5,756	$ 4,880

Risk Management and Derivatives - Narrative (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Derivative [Line Items]
Notional value of outstanding foreign currency contracts	$ 601,000
Minimum maturity of foreign currency forward contract	1 month
Maturity of foreign currency forward contract	11 months
Foreign currency cash flow hedge gain (loss) reclassified to cost of goods sold	$ (400)	$ 300
Interest Rate Swap
Derivative [Line Items]
Notional value of outstanding foreign currency contracts	135,600
Gain (loss) on derivative	900	2,000
Fair value of interest rate derivative assets	1,100
Fair value of interest rate derivative liabilities		(400)
Level 2
Derivative [Line Items]
Fair value of foreign currency contracts liability	(6,800)
Derivative foreign currency contracts	$ (6,818)	$ 15,238

Risk Management and Derivatives - Changes In Foreign Currency Exchange Rates And Derivative Foreign Currency Forward Contracts (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Foreign Currency Exchange Gain Loss [Line Items]
Unrealized foreign currency exchange rate gains (losses)	$ 29,247	$ (12,627)	$ (33,359)
Foreign Currency Exchange Rates
Foreign Currency Exchange Gain Loss [Line Items]
Unrealized foreign currency exchange rate gains (losses)	29,246	(12,627)	(33,359)
Realized foreign currency exchange rate gains (losses)	611	(6,906)	7,643
Gain (Loss) on Derivative Instruments
Foreign Currency Exchange Gain Loss [Line Items]
Unrealized derivative gains (losses)	(1,217)	729	388
Realized derivative gains (losses)	$ (26,537)	$ 15,192	$ 16,404

Related Party Transactions (Details) - USD ($)	1 Months Ended	12 Months Ended
Related Party Transactions (Details) - USD ($)	Jun. 30, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Corporate Headquarters Expansion \| Entity controlled by CEO
Related Party Transaction [Line Items]
Purchase from related party	$ 70,300,000
Obligations owed by either party		$ 0
Related Party - Operating Lease Agreement
Related Party Transaction [Line Items]
Fees paid		2,000,000	$ 2,000,000	$ 2,000,000
Amount payable to related party		$ 0	$ 0

Segment Data And Related Information (Geographic Distribution Of The Company's Net Revenues And Operating Income) (Detail) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Segment Reporting Information [Line Items]
Net revenues	$ 1,365,362	$ 1,405,615	$ 1,088,245	$ 1,117,331	$ 1,305,277	$ 1,471,573	$ 1,000,783	$ 1,047,702	$ 4,976,553	$ 4,825,335	$ 3,963,313
Total operating income	$ (37,088)	$ 62,180	$ (4,785)	$ 7,536	$ 163,900	$ 199,310	$ 19,378	$ 34,883	27,843	417,471	408,547
Interest expense, net									(34,538)	(26,434)	(14,628)
Other expense, net									(3,614)	(2,755)	(7,234)
Income before income taxes									(10,309)	388,282	386,685
North America
Segment Reporting Information [Line Items]
Net revenues									3,802,406	4,005,314	3,455,737
Total operating income									20,179	408,424	460,961
EMEA
Segment Reporting Information [Line Items]
Net revenues									469,997	330,584	203,109
Total operating income									17,976	11,420	3,122
Asia-Pacific
Segment Reporting Information [Line Items]
Net revenues									433,647	268,607	144,877
Total operating income									82,039	68,338	36,358
Latin America
Segment Reporting Information [Line Items]
Net revenues									181,324	141,793	106,175
Total operating income									(37,085)	(33,891)	(30,593)
Connected Fitness
Segment Reporting Information [Line Items]
Net revenues									89,179	80,447	53,415
Total operating income									(55,266)	(36,820)	(61,301)
Intersegment Eliminations
Segment Reporting Information [Line Items]
Net revenues									$ 0	$ (1,410)	$ 0

Segment Date and Related Information (Charges Incurred and Expected to be Incurred) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Segment Reporting Information [Line Items]
Restructuring and impairment charges		$ 124,049	$ 0	$ 0
Inventory write-offs		5,077
North America
Segment Reporting Information [Line Items]
Restructuring and impairment charges		63,170
EMEA
Segment Reporting Information [Line Items]
Restructuring and impairment charges		1,525
Asia-Pacific
Segment Reporting Information [Line Items]
Restructuring and impairment charges		38
Latin America
Segment Reporting Information [Line Items]
Restructuring and impairment charges		11,506
Connected Fitness
Segment Reporting Information [Line Items]
Restructuring and impairment charges		$ 47,810
Forecast
Segment Reporting Information [Line Items]
Restructuring and impairment charges	$ 133,000
Forecast \| North America
Segment Reporting Information [Line Items]
Restructuring and impairment charges	109,000
Forecast \| EMEA
Segment Reporting Information [Line Items]
Restructuring and impairment charges	6,000
Forecast \| Asia-Pacific
Segment Reporting Information [Line Items]
Restructuring and impairment charges	0
Forecast \| Latin America
Segment Reporting Information [Line Items]
Restructuring and impairment charges	18,000
Forecast \| Connected Fitness
Segment Reporting Information [Line Items]
Restructuring and impairment charges	$ 0

Segment Data and Related Information (Long-lived Assets) (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Revenues from External Customers and Long-Lived Assets [Line Items]
Long-lived assets	$ 885,774	$ 804,211
United States
Revenues from External Customers and Long-Lived Assets [Line Items]
Long-lived assets	763,477	728,841
Canada
Revenues from External Customers and Long-Lived Assets [Line Items]
Long-lived assets	14,077	11,126
North America
Revenues from External Customers and Long-Lived Assets [Line Items]
Long-lived assets	777,554	739,967
Other foreign countries
Revenues from External Customers and Long-Lived Assets [Line Items]
Long-lived assets	$ 108,220	$ 64,244

Segment Data And Related Information (Net Revenues By Product Category) (Detail) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Segment Reporting Information [Line Items]
Total net revenues									$ 4,770,799	$ 4,646,449	$ 3,825,691
License revenues									116,575	99,849	84,207
Net revenues	$ 1,365,362	$ 1,405,615	$ 1,088,245	$ 1,117,331	$ 1,305,277	$ 1,471,573	$ 1,000,783	$ 1,047,702	4,976,553	4,825,335	3,963,313
Apparel
Segment Reporting Information [Line Items]
Total net revenues									3,287,121	3,229,142	2,801,062
Footwear
Segment Reporting Information [Line Items]
Total net revenues									1,037,840	1,010,693	677,744
Accessories
Segment Reporting Information [Line Items]
Total net revenues									445,838	406,614	346,885
Connected Fitness
Segment Reporting Information [Line Items]
Total net revenues									89,179	80,447	53,415
Net revenues									89,179	80,447	53,415
Intersegment Eliminations
Segment Reporting Information [Line Items]
Net revenues									0	(1,410)	0
United States
Segment Reporting Information [Line Items]
Total net revenues in the United States									$ 3,626,600	$ 3,843,700	$ 3,317,000

Unaudited Quarterly Financial Data (Selected Quarterly Financial Data) (Details) - USD ($) $ / shares in Units, $ in Thousands		3 Months Ended								12 Months Ended
	Jun. 03, 2016	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Quarterly Financial Information [Line Items]
Net revenues										$ 4,770,799	$ 4,646,449	$ 3,825,691
Gross profit		$ 589,704	$ 645,350	$ 498,246	$ 505,423	$ 583,704	$ 698,624	$ 477,647	$ 480,636	2,238,723	2,240,611	1,905,547
Income from operations		(37,088)	62,180	(4,785)	7,536	163,900	199,310	19,378	34,883	27,843	417,471	408,547
Net income (loss)		(87,922)	54,242	(12,308)	(2,272)	103,230	128,225	6,344	19,180	(48,260)	256,979	232,573
Adjustment payment to Class C capital stockholders	$ 59,000
Net income (loss) available to all stockholders		(87,922)	54,242	(12,308)	(2,272)	103,230	128,225	(52,656)	19,180	(48,260)	197,979	232,573
Net revenues		$ 1,365,362	$ 1,405,615	$ 1,088,245	$ 1,117,331	$ 1,305,277	$ 1,471,573	$ 1,000,783	$ 1,047,702	$ 4,976,553	$ 4,825,335	$ 3,963,313
Class A Common Stock And Class B Convertible Common Stock
Quarterly Financial Information [Line Items]
Basic net income (loss) per share (USD Per Share)		$ (0.20)	$ 0.12	$ (0.03)	$ (0.01)	$ 0.24	$ 0.29	$ (0.12)	$ 0.04	$ (0.11)	$ 0.45	$ 0.54
Diluted net income (loss) per share (USD Per Share)		(0.20)	0.12	(0.03)	(0.01)	$ 0.23	$ 0.29	$ (0.12)	$ 0.04	$ (0.11)	$ 0.45	$ 0.53
Class C Common Stock
Quarterly Financial Information [Line Items]
Adjustment payment to Class C capital stockholders						$ 0	$ 0	$ 59,000	$ 0	$ 0	$ 59,000	$ 0
Basic net income (loss) per share (USD Per Share)		(0.20)	0.12	(0.03)	(0.01)	$ 0.24	$ 0.29	$ 0.15	$ 0.04	$ (0.11)	$ 0.72	$ 0.54
Diluted net income (loss) per share (USD Per Share)		$ (0.20)	$ 0.12	$ (0.03)	$ (0.01)	$ 0.23	$ 0.29	$ 0.15	$ 0.04	$ (0.11)	$ 0.71	$ 0.53

Schedule II - Valuation And Qualifying Accounts (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Allowance for doubtful accounts
Valuation and Qualifying Accounts Disclosure [Line Items]
Balance at Beginning of Year	$ 11,341	$ 5,930	$ 3,693
Charged to Costs and Expenses	9,520	23,575	2,951
Write-Offs Net of Recoveries	(1,149)	(18,164)	(714)
Balance at End of Year	19,712	11,341	5,930
Sales returns and allowances
Valuation and Qualifying Accounts Disclosure [Line Items]
Balance at Beginning of Year	121,286	72,615	52,973
Charged to Costs and Expenses	285,474	179,445	145,828
Write-Offs Net of Recoveries	(215,966)	(130,774)	(126,186)
Balance at End of Year	190,794	121,286	72,615
Deferred tax asset valuation allowance
Valuation and Qualifying Accounts Disclosure [Line Items]
Balance at Beginning of Year	37,969	24,043	15,550
Charged to Costs and Expenses	40,282	13,951	8,493
Write-Offs Net of Recoveries	(4,707)	(25)	0
Balance at End of Year	$ 73,544	$ 37,969	$ 24,043

Description of the Business	12 Months Ended
Description of the Business	Dec. 31, 2017
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Description of the Business	Description of the Business Under Armour, Inc. is a developer, marketer and distributor of branded performance apparel, footwear and accessories. These products are sold worldwide and worn by athletes at all levels, from youth to professional on playing fields around the globe, as well as by consumers with active lifestyles. The Under Armour Connected Fitness^TMplatform powers the world's largest digital health and fitness community. The Company uses this platform to engage its consumers and increase awareness and sales of its products.

Segment Data and Related Information (Narrative) (Details)	12 Months Ended
	Dec. 31, 2017 industry
Segment Reporting [Abstract]
Number of industries in each geographic segment	1