CarMax Auto Finance Income (Components Of CarMax Auto Finance Income) (Details) (USD $)	3 Months Ended								12 Months Ended
	Feb. 28, 2014	Nov. 30, 2013	Aug. 31, 2013	May 31, 2013	Feb. 28, 2013	Nov. 30, 2012	Aug. 31, 2012	May 31, 2012	Feb. 28, 2014		Feb. 28, 2013		Feb. 29, 2012
Auto Finance Income [Line Items]
Interest and fee income									$ 548,000,000		$ 495,300,000		$ 448,700,000
Interest expense									(90,000,000)		(95,100,000)		(106,100,000)
Total interest margin									458,000,000		400,200,000		342,600,000
Provision for loan losses									(72,200,000)		(56,200,000)		(36,400,000)
Total interest margin after provision for loan losses									385,800,000		344,000,000		306,200,000
Other income									100,000				1,500,000
Payroll and fringe benefit expense									(22,600,000)		(21,200,000)		(20,700,000)
Other direct expenses									(27,100,000)		(23,500,000)		(24,800,000)
Total direct expenses									(49,700,000)		(44,700,000)		(45,500,000)
CarMax Auto Finance income	80,821,000	83,905,000	84,422,000	87,019,000	75,958,000	72,454,000	75,676,000	75,179,000	336,167,000		299,267,000		262,185,000
Total average managed receivables									$ 6,629,500,000		$ 5,385,500,000		$ 4,662,400,000
Interest And Fee Income [Member]
Auto Finance Income [Line Items]
Item as percent of total average managed receivables									8.30%	[1]	9.20%	[1]	9.60%	[1]
Interest Expense [Member]
Auto Finance Income [Line Items]
Item as percent of total average managed receivables									(1.40%)	[1]	(1.80%)	[1]	(2.30%)	[1]
Total Interest Margin [Member]
Auto Finance Income [Line Items]
Item as percent of total average managed receivables									6.90%	[1]	7.40%	[1]	7.30%	[1]
Provision For Loan Losses [Member]
Auto Finance Income [Line Items]
Item as percent of total average managed receivables									(1.10%)	[1]	(1.00%)	[1]	(0.80%)	[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]	6.40%	[1]	6.60%	[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]	(0.40%)	[1]
Other Direct Expenses [Member]
Auto Finance Income [Line Items]
Item as percent of total average managed receivables									(0.40%)	[1]	(0.40%)	[1]	(0.50%)	[1]
Total Direct Expenses [Member]
Auto Finance Income [Line Items]
Item as percent of total average managed receivables									(0.80%)	[1]	(0.80%)	[1]	(1.00%)	[1]
CAF Income [Member]
Auto Finance Income [Line Items]
Item as percent of total average managed receivables									5.10%	[1]	5.60%	[1]	5.60%	[1]

[1] Percent of total average managed receivables.