CarMax Auto Finance Income (Components Of CarMax Auto Finance Income) (Details) (USD $)	3 Months Ended				6 Months Ended
	Aug. 31, 2012		Aug. 31, 2011		Aug. 31, 2012		Aug. 31, 2011
Auto Finance Income [Line Items]
Interest and fee income	$ 123,500,000		$ 111,800,000		$ 243,800,000		$ 219,700,000
Interest expense	(23,900,000)		(26,200,000)		(49,000,000)		(54,700,000)
Total interest margin	99,600,000		85,600,000		194,800,000		165,000,000
Provision for loan losses	(12,900,000)		(10,800,000)		(22,100,000)		(9,800,000)
Total interest margin after provision for loan losses	86,700,000		74,800,000		172,700,000		155,200,000
Other (loss) income	(200,000)		400,000		(200,000)		1,100,000
Payroll and fringe benefit expense	(5,400,000)		(5,100,000)		(10,700,000)		(10,400,000)
Other direct expenses	(5,400,000)		(6,300,000)		(10,900,000)		(12,400,000)
Total direct expenses	(10,800,000)		(11,400,000)		(21,600,000)		(22,800,000)
CarMax Auto Finance income	75,676,000		63,826,000	[1]	150,855,000		133,487,000	[1]
Total average managed receivables	$ 5,245,400,000		$ 4,596,600,000		$ 5,160,300,000		$ 4,492,200,000
Interest And Fee Income [Member]
Auto Finance Income [Line Items]
Item as percent of total average managed receivables	9.40%	[2]	9.70%	[2]	9.40%	[2]	9.80%	[2]
Interest Expense [Member]
Auto Finance Income [Line Items]
Item as percent of total average managed receivables	(1.80%)	[2]	(2.30%)	[2]	(1.90%)	[2]	(2.40%)	[2]
Total Interest Margin [Member]
Auto Finance Income [Line Items]
Item as percent of total average managed receivables	7.60%	[2]	7.50%	[2]	7.50%	[2]	7.30%	[2]
Provision For Loan Losses [Member]
Auto Finance Income [Line Items]
Item as percent of total average managed receivables	(1.00%)	[2]	(0.90%)	[2]	(0.90%)	[2]	(0.40%)	[2]
Total Interest Margin After Provision For Loan Losses [Member]
Auto Finance Income [Line Items]
Item as percent of total average managed receivables	6.60%	[2]	6.50%	[2]	6.70%	[2]	6.90%	[2]
Other (Loss) Income [Member]
Auto Finance Income [Line Items]
Item as percent of total average managed receivables	0.00%	[2]	0.00%	[2]	0.00%	[2]	0.00%	[2]
Payroll And Fringe Benefit Expense [Member]
Auto Finance Income [Line Items]
Item as percent of total average managed receivables	(0.40%)	[2]	(0.40%)	[2]	(0.40%)	[2]	(0.50%)	[2]
Other Direct Expenses [Member]
Auto Finance Income [Line Items]
Item as percent of total average managed receivables	(0.40%)	[2]	(0.50%)	[2]	(0.40%)	[2]	(0.60%)	[2]
Total Direct Expenses [Member]
Auto Finance Income [Line Items]
Item as percent of total average managed receivables	(0.80%)	[2]	(1.00%)	[2]	(0.80%)	[2]	(1.00%)	[2]
CarMax Auto Finance Income [Member]
Auto Finance Income [Line Items]
Item as percent of total average managed receivables	5.80%	[2]	5.60%	[2]	5.80%	[2]	5.90%	[2]

[1] As discussed in Note 2, fiscal 2012 reflects the revisions to correct our accounting for sale-leaseback transactions.

[2] Annualized percent of total average managed receivables.