CarMax Auto Finance Income (Components Of CarMax Auto Finance Income) (Details) (USD $)
3 Months Ended
May 31, 2014
May 31, 2013
Auto Finance Income [Line Items]    
Interest and fee income $ 147,000,000 $ 133,500,000
Interest expense (23,100,000) (22,800,000)
Total interest margin 123,900,000 110,700,000
Provision for loan losses (15,800,000) (11,300,000)
Total interest margin after provision for loan losses 108,100,000 99,400,000
Payroll and fringe benefit expense (6,200,000) (5,500,000)
Other direct expenses (7,300,000) (6,900,000)
Total direct expenses (13,500,000) (12,400,000)
CarMax Auto Finance income 94,615,000 87,019,000
Total average managed receivables $ 7,390,100,000 $ 6,152,500,000
Interest And Fee Income [Member]
   
Auto Finance Income [Line Items]    
Item as percent of total average managed receivables 8.00% [1] 8.70% [1]
Interest Expense [Member]
   
Auto Finance Income [Line Items]    
Item as percent of total average managed receivables (1.20%) [1] (1.50%) [1]
Total Interest Margin [Member]
   
Auto Finance Income [Line Items]    
Item as percent of total average managed receivables 6.70% [1] 7.20% [1]
Provision For Loan Losses [Member]
   
Auto Finance Income [Line Items]    
Item as percent of total average managed receivables (0.90%) [1] (0.70%) [1]
Total Interest Margin After Provision For Loan Losses [Member]
   
Auto Finance Income [Line Items]    
Item as percent of total average managed receivables 5.80% [1] 6.50% [1]
Payroll And Fringe Benefit Expense [Member]
   
Auto Finance Income [Line Items]    
Item as percent of total average managed receivables (0.30%) [1] (0.40%) [1]
Other Direct Expenses [Member]
   
Auto Finance Income [Line Items]    
Item as percent of total average managed receivables (0.40%) [1] (0.40%) [1]
Total Direct Expenses [Member]
   
Auto Finance Income [Line Items]    
Item as percent of total average managed receivables (0.70%) [1] (0.80%) [1]
CAF Income [Member]
   
Auto Finance Income [Line Items]    
Item as percent of total average managed receivables 5.10% [1] 5.70% [1]
[1] Annualized percentage of total average managed receivables.