v2.4.0.8
Document and Entity Information
3 Months Ended
Mar. 31, 2014
Apr. 30, 2014
Class A Common Stock [Member]
Apr. 30, 2014
Class B Convertible Common Stock [Member]
Entity Information [Line Items]      
Document Type 10-Q    
Amendment Flag false    
Document Period End Date Mar. 31, 2014    
Document Fiscal Year Focus 2014    
Document Fiscal Period Focus Q1    
Trading Symbol UA    
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 Common Stock, Shares Outstanding   173,959,046 39,155,000