Cover Page - USD ($)	12 Months Ended
	Mar. 31, 2023	May 15, 2023	Sep. 30, 2022
Document Information [Line Items]
Document Type	10-K
Document Annual Report	true
Document Period End Date	Mar. 31, 2023
Current Fiscal Year End Date	--03-31
Document Transition Report	false
Entity File Number	001-33202
Entity Registrant Name	UNDER ARMOUR, INC.
Entity Incorporation, State or Country Code	MD
Entity Tax Identification Number	52-1990078
Entity Address, Address Line One	1020 Hull Street
Entity Address, City or Town	Baltimore
Entity Address, State or Province	MD
Entity Address, Postal Zip Code	21230
City Area Code	410
Local Phone Number	468-2512
Entity Well-known Seasoned Issuer	No
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
ICFR Auditor Attestation Flag	true
Entity Shell Company	false
Documents Incorporated by Reference	Portions of Under Armour, Inc.’s Proxy Statement for the Annual Meeting of Stockholders to be held on August 29, 2023 are incorporated by reference in Part III of this Annual Report on Form 10-K.
Amendment Flag	false
Document Fiscal Year Focus	2023
Document Fiscal Period Focus	FY
Entity Central Index Key	0001336917
Class A Common Stock
Document Information [Line Items]
Title of 12(b) Security	Class A Common Stock
Trading Symbol	UAA
Security Exchange Name	NYSE
Entity Public Float			$ 1,250,424,223
Entity Common Stock, Shares Outstanding		188,704,689
Class C Common Stock
Document Information [Line Items]
Title of 12(b) Security	Class C Common Stock
Trading Symbol	UA
Security Exchange Name	NYSE
Entity Public Float			$ 1,147,881,110
Entity Common Stock, Shares Outstanding		221,441,390
Class B Convertible Common Stock
Document Information [Line Items]
Entity Common Stock, Shares Outstanding		34,450,000