CarMax Auto Finance (Components Of CarMax Auto Finance Income) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Aug. 31, 2021	Aug. 31, 2020	Aug. 31, 2021	Aug. 31, 2020
Auto Finance Income [Line Items]
Interest and fee income	$ 324,100	$ 280,100	$ 634,400	$ 562,600
Interest expense	(60,600)	(81,300)	(126,400)	(165,900)
Total interest margin	263,500	198,800	508,000	396,700
Provision for loan losses	(35,500)	(26,000)	(11,100)	(148,000)
Total interest margin after provision for loan losses	228,000	172,800	496,900	248,700
Total other expense	0	(300)	0	(2,200)
Payroll and fringe benefit expense	(12,400)	(11,400)	(25,000)	(22,600)
Other Depreciation and Amortization	(200)	(200)	(400)	(400)
Other direct expenses	(15,300)	(13,800)	(29,700)	(25,400)
Total direct expenses	(27,900)	(25,400)	(55,100)	(48,400)
CarMax Auto Finance income	200,033	147,195	441,764	198,145
Total average managed receivables	$ 14,683,300	$ 13,218,800	$ 14,416,000	$ 13,313,600
Interest and fee income, percent
Auto Finance Income [Line Items]
Item as percent of total average managed receivables	8.80%	8.50%	8.80%	8.50%
Interest expense, percent
Auto Finance Income [Line Items]
Item as percent of total average managed receivables	(1.70%)	(2.50%)	(1.80%)	(2.50%)
Total interest margin, percent
Auto Finance Income [Line Items]
Item as percent of total average managed receivables	7.20%	6.00%	7.00%	6.00%
Provision for loan losses, percent
Auto Finance Income [Line Items]
Item as percent of total average managed receivables	(1.00%)	(0.80%)	(0.20%)	(2.20%)
Total interest margin after provision for loan losses, percent
Auto Finance Income [Line Items]
Item as percent of total average managed receivables	6.20%	5.20%	6.90%	3.70%
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	0.00%	0.00%	0.00%	0.00%
Other direct expenses, percent
Auto Finance Income [Line Items]
Item as percent of total average managed receivables	(0.40%)	(0.40%)	(0.40%)	(0.40%)
Total direct expenses, percent
Auto Finance Income [Line Items]
Item as percent of total average managed receivables	(0.80%)	(0.80%)	(0.80%)	(0.70%)
CarMax Auto Finance income, percent
Auto Finance Income [Line Items]
Item as percent of total average managed receivables	5.40%	4.50%	6.10%	3.00%