CarMax Auto Finance (Components Of CarMax Auto Finance Income) (Details) - USD ($) $ in Thousands	3 Months Ended			9 Months Ended
	Nov. 30, 2020	May 31, 2020	Nov. 30, 2019	Nov. 30, 2020	Nov. 30, 2019
Auto Finance Income [Line Items]
Interest and fee income	$ 288,500		$ 278,900	$ 851,100	$ 820,800
Interest expense	(77,100)		(90,400)	(243,000)	(268,400)
Total interest margin	211,400		188,500	608,100	552,400
Provision for loan losses	(8,200)	$ (122,000)	(49,000)	(156,100)	(132,700)
Total interest margin after provision for loan losses	203,200		139,500	452,000	419,700
Total other expense	0		0	(2,200)	0
Payroll and fringe benefit expense	(11,600)		(10,800)	(34,200)	(31,300)
Other direct expenses	(15,200)		(14,700)	(41,000)	(44,300)
Total direct expenses	(26,800)		(25,500)	(75,200)	(75,600)
CarMax Auto Finance income	176,445		114,033	374,590	344,123
Total average managed receivables	$ 13,517,500		$ 13,239,200	$ 13,381,600	$ 12,986,200
Interest and fee income, percent
Auto Finance Income [Line Items]
Item as percent of total average managed receivables	8.50%		8.40%	8.50%	8.40%
Interest expense, percent
Auto Finance Income [Line Items]
Item as percent of total average managed receivables	(2.30%)		(2.70%)	(2.40%)	(2.80%)
Total interest margin, percent
Auto Finance Income [Line Items]
Item as percent of total average managed receivables	6.30%		5.70%	6.10%	5.70%
Provision for loan losses, percent
Auto Finance Income [Line Items]
Item as percent of total average managed receivables	(0.20%)		(1.50%)	(1.60%)	(1.40%)
Total interest margin after provision for loan losses, percent
Auto Finance Income [Line Items]
Item as percent of total average managed receivables	6.00%		4.20%	4.50%	4.30%
Total other expense, percent
Auto Finance Income [Line Items]
Item as percent of total average managed receivables	0.00%		0.00%	0.00%	0.00%
Payroll and fringe benefit expense, percent
Auto Finance Income [Line Items]
Item as percent of total average managed receivables	(0.30%)		(0.30%)	(0.30%)	(0.30%)
Other direct expenses, percent
Auto Finance Income [Line Items]
Item as percent of total average managed receivables	(0.40%)		(0.40%)	(0.40%)	(0.50%)
Total direct expenses, percent
Auto Finance Income [Line Items]
Item as percent of total average managed receivables	(0.80%)		(0.80%)	(0.70%)	(0.80%)
CarMax Auto Finance income, percent
Auto Finance Income [Line Items]
Item as percent of total average managed receivables	5.20%		3.40%	3.70%	3.50%