CarMax Auto Finance Income (Components Of CarMax Auto Finance Income) (Details) (USD $)	3 Months Ended				9 Months Ended
	Nov. 30, 2013		Nov. 30, 2012		Nov. 30, 2013		Nov. 30, 2012
Auto Finance Income [Line Items]
Interest and fee income	$ 138,300,000		$ 125,100,000		$ 409,000,000		$ 368,900,000
Interest expense	(22,200,000)		(23,300,000)		(67,600,000)		(72,400,000)
Total interest margin	116,100,000		101,800,000		341,400,000		296,500,000
Provision for loan losses	(19,700,000)		(18,100,000)		(49,000,000)		(40,200,000)
Total interest margin after provision for loan losses	96,400,000		83,700,000		292,400,000		256,300,000
Other income	0		200,000		100,000		0
Payroll and fringe benefit expense	(5,600,000)		(5,200,000)		(16,700,000)		(15,900,000)
Other direct expenses	(6,900,000)		(6,200,000)		(20,500,000)		(17,100,000)
Total direct expenses	(12,500,000)		(11,400,000)		(37,200,000)		(33,000,000)
CarMax Auto Finance income	83,905,000		72,454,000		255,346,000		223,309,000
Total average managed receivables	$ 6,805,300,000		$ 5,477,400,000		$ 6,491,400,000		$ 5,266,000,000
Interest And Fee Income [Member]
Auto Finance Income [Line Items]
Item as percent of total average managed receivables	8.10%	[1]	9.10%	[1]	8.40%	[1]	9.30%	[1]
Interest Expense [Member]
Auto Finance Income [Line Items]
Item as percent of total average managed receivables	(1.30%)	[1]	(1.70%)	[1]	(1.40%)	[1]	(1.80%)	[1]
Total Interest Margin [Member]
Auto Finance Income [Line Items]
Item as percent of total average managed receivables	6.80%	[1]	7.40%	[1]	7.00%	[1]	7.50%	[1]
Provision For Loan Losses [Member]
Auto Finance Income [Line Items]
Item as percent of total average managed receivables	(1.20%)	[1]	(1.30%)	[1]	(1.00%)	[1]	(1.00%)	[1]
Total Interest Margin After Provision For Loan Losses [Member]
Auto Finance Income [Line Items]
Item as percent of total average managed receivables	5.70%	[1]	6.10%	[1]	6.00%	[1]	6.50%	[1]
Other Income [Member]
Auto Finance Income [Line Items]
Item as percent of total average managed receivables	0.00%	[1]	0.00%	[1]	0.00%	[1]	0.00%	[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]	(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]	(0.50%)	[1]	(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]	(0.80%)	[1]	(0.80%)	[1]
CAF Income [Member]
Auto Finance Income [Line Items]
Item as percent of total average managed receivables	4.90%	[1]	5.30%	[1]	5.20%	[1]	5.70%	[1]

[1] Annualized percent of total average managed receivables.