Description of Business and Basis of Presentation	9 Months Ended
Description of Business and Basis of Presentation	Sep. 30, 2021
Organization, Consolidation and Presentation of Financial Statements [Abstract]
DESCRIPTION OF BUSINESS AND BASIS OF PRESENTATION	DESCRIPTION OF BUSINESS AND BASIS OF PRESENTATION Business Under Armour, Inc. (together with its wholly owned subsidiaries, the "Company") is a developer, marketer, and distributor of branded athletic performance apparel, footwear, and accessories. The Company creates products engineered to solve problems and make athletes better. The Company's products are made, sold, and worn worldwide. Basis of Presentation The accompanying unaudited condensed consolidated financial statements include the accounts of Under Armour, Inc. and its wholly owned subsidiaries. Certain information in footnote disclosures normally included in annual financial statements were condensed or omitted for the interim periods presented in accordance with the rules and regulations of the Securities and Exchange Commission (the “SEC”) and accounting principles generally accepted in the United States of America ("U.S. GAAP") for interim consolidated financial statements. These unaudited condensed consolidated financial statements are presented in U.S. Dollars. In the opinion of management, all adjustments consisting of normal, recurring adjustments considered necessary for a fair statement of the financial position and results of operations were included. Intercompany balances and transactions were eliminated upon consolidation. The unaudited condensed consolidated balance sheet as of September 30, 2021 is derived from the audited financial statements included in the Company’s Annual Report on Form 10-K for the fiscal year ended December 31, 2020 ("Fiscal 2020"), filed with the SEC on February 24, 2021 ("Annual Report on Form 10-K for Fiscal 2020"), which should be read in conjunction with these unaudited condensed consolidated financial statements. The unaudited results for the three and nine months ended September 30, 2021, are not necessarily indicative of the results to be expected for the fiscal year ending December 31, 2021 ("Fiscal 2021"), or any other portions thereof. Connected Fitness Prior to January 1, 2021, the Company's previously reported "Connected Fitness" segment was composed of digital subscription and advertising conducted through various platforms, predominantly the MyFitnessPal, MapMyFitness, consisting of applications such as MapMyRun and MapMyRide (collectively "MMR"), and Endomondo platforms. While the Company continues to operate the MMR platforms, MyFitnessPal was sold in December 2020 and Endomondo was wound down in December 2020 as part of the Company's 2020 restructuring plan. As a result of these changes, beginning in the first quarter of Fiscal 2021, the Company no longer reports Connected Fitness as a discrete reportable segment. The operating results of MMR are now included within the Company’s Corporate Other segment. Where applicable, all prior periods that used to separately reflect financial information about the Connected Fitness business have been recast to be included within the Corporate Other reportable segment, in order to conform with current period presentation. Such reclassifications did not affect total consolidated net revenues, consolidated income from operations or consolidated net income. Management Estimates and COVID-19 Update The preparation of financial statements in conformity with U.S. GAAP requires management to make estimates, judgments, and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the unaudited condensed consolidated financial statements and the reported amounts of revenues and expenses during the reporting period. These estimates, judgments and assumptions are evaluated on an on-going basis. The Company bases its estimates on historical experience and on various other assumptions that it believes are reasonable at that time; however, actual results could differ from these estimates. Further, COVID-19 continues to significantly impact the global economy. As the impacts of the pandemic continue to evolve, estimates and assumptions about future events and their effects cannot be determined with certainty and therefore require increased judgment. The extent to which the evolving pandemic impacts the Company's financial statements will depend on a number of factors including, but not limited to, any new information that may emerge concerning the severity of COVID-19 and the actions that governments around the world may take to contain the virus or treat its impact. While the Company believes it has made appropriate accounting estimates and assumptions based on the facts and circumstances available as of this reporting date, the Company may experience further impacts based on long-term effects on the Company's customers and the countries in which the Company operates. Please see the risk factors discussed in Part I, Item 1A "Risk Factors" in the Company's Annual Report on Form 10-K for Fiscal 2020.