v2.4.0.6
Document and Entity Information
9 Months Ended
Sep. 30, 2012
Oct. 31, 2012
Class A Common Stock [Member]
Oct. 31, 2012
Class B Convertible Common Stock [Member]
Entity Information [Line Items]      
Document Type 10-Q    
Amendment Flag false    
Document Period End Date Sep. 30, 2012    
Document Fiscal Year Focus 2012    
Document Fiscal Period Focus Q3    
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   83,152,708 21,500,000