CarMax Auto Finance (Components Of CarMax Auto Finance Income) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Nov. 30, 2021	Nov. 30, 2020	Nov. 30, 2021	Nov. 30, 2020
Auto Finance Income [Line Items]
Interest and fee income	$ 330,000	$ 288,500	$ 964,400	$ 851,100
Interest expense	(53,600)	(77,100)	(180,000)	(243,000)
Total interest margin	276,400	211,400	784,400	608,100
Provision for loan losses	(76,200)	(8,200)	(87,300)	(156,100)
Total interest margin after provision for loan losses	200,200	203,200	697,100	452,000
Total other expense	0	0	0	(2,200)
Payroll and fringe benefit expense	(12,700)	(11,600)	(37,700)	(34,200)
Other Depreciation and Amortization	(2,400)	(200)	(2,800)	(600)
Other direct expenses	(19,200)	(15,000)	(48,900)	(40,400)
Total direct expenses	(34,300)	(26,800)	(89,400)	(75,200)
CarMax Auto Finance income	165,968	176,445	607,732	374,590
Total average managed receivables	$ 15,288,800	$ 13,517,500	$ 14,706,900	$ 13,381,600
Interest and fee income, percent
Auto Finance Income [Line Items]
Item as percent of total average managed receivables	8.60%	8.50%	8.70%	8.50%
Interest expense, percent
Auto Finance Income [Line Items]
Item as percent of total average managed receivables	(1.40%)	(2.30%)	(1.60%)	(2.40%)
Total interest margin, percent
Auto Finance Income [Line Items]
Item as percent of total average managed receivables	7.20%	6.30%	7.10%	6.10%
Provision for loan losses, percent
Auto Finance Income [Line Items]
Item as percent of total average managed receivables	(2.00%)	(0.20%)	(0.80%)	(1.60%)
Total interest margin after provision for loan losses, percent
Auto Finance Income [Line Items]
Item as percent of total average managed receivables	5.20%	6.00%	6.30%	4.50%
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 Depreciation and Amortization
Auto Finance Income [Line Items]
Item as percent of total average managed receivables	(0.10%)	0.00%	0.00%	0.00%
Other direct expenses, percent
Auto Finance Income [Line Items]
Item as percent of total average managed receivables	(0.50%)	(0.40%)	(0.40%)	(0.40%)
Total direct expenses, percent
Auto Finance Income [Line Items]
Item as percent of total average managed receivables	(0.90%)	(0.80%)	(0.80%)	(0.70%)
CarMax Auto Finance income, percent
Auto Finance Income [Line Items]
Item as percent of total average managed receivables	4.30%	5.20%	5.50%	3.70%