Consolidated Statements Of Earnings - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Nov. 30, 2017	Nov. 30, 2016	Nov. 30, 2017	Nov. 30, 2016
Revenue, Net [Abstract]
Used vehicle sales	$ 3,425,540	$ 3,090,613	$ 10,963,113	$ 9,820,401
Wholesale vehicle sales	552,754	488,385	1,653,911	1,616,528
Other sales and revenues	128,723	122,526	418,967	388,229
NET SALES AND OPERATING REVENUES	4,107,017	3,701,524	13,035,991	11,825,158
Cost of sales	3,567,829	3,198,389	11,243,860	10,204,024
GROSS PROFIT	539,188	503,135	1,792,131	1,621,134
CARMAX AUTO FINANCE INCOME	102,810	89,359	320,109	286,086
Selling, general and administrative expenses	399,672	356,735	1,208,237	1,103,091
Interest expense	17,405	15,071	51,079	40,063
Other (income) expense	(279)	1,027	(561)	(24)
Earnings before income taxes	225,200	219,661	853,485	764,090
Income tax provision	76,360	83,016	311,519	289,723
NET EARNINGS	$ 148,840	$ 136,645	$ 541,966	$ 474,367
WEIGHTED AVERAGE COMMON SHARES:
Basic, shares	181,888	189,200	183,324	191,431
Diluted, shares	184,033	190,818	185,201	193,239
NET EARNINGS PER SHARE:
Basic (in dollars per share)	$ 0.82	$ 0.72	$ 2.96	$ 2.48
Diluted (in dollars per share)	$ 0.81	$ 0.72	$ 2.93	$ 2.45
Used vehicle sales, percent
Percentage of Sales
Item as a percent of net sales and operating revenues	83.40%	83.50%	84.10%	83.00%
Wholesale vehicle sales, percent
Percentage of Sales
Item as a percent of net sales and operating revenues	13.50%	13.20%	12.70%	13.70%
Other sales and revenues, percent
Percentage of Sales
Item as a percent of net sales and operating revenues	3.10%	3.30%	3.20%	3.30%
NET SALES AND OPERATING REVENUES, percent
Percentage of Sales
Item as a percent of net sales and operating revenues	100.00%	100.00%	100.00%	100.00%
Cost of sales, percent
Percentage of Sales
Item as a percent of net sales and operating revenues	86.90%	86.40%	86.30%	86.30%
GROSS PROFIT, percent
Percentage of Sales
Item as a percent of net sales and operating revenues	13.10%	13.60%	13.70%	13.70%
CARMAX AUTO FINANCE INCOME, percent
Percentage of Sales
Item as a percent of net sales and operating revenues	2.50%	2.40%	2.50%	2.40%
Selling, general and administrative expenses, percent
Percentage of Sales
Item as a percent of net sales and operating revenues	9.70%	9.60%	9.30%	9.30%
Interest expense, percent
Percentage of Sales
Item as a percent of net sales and operating revenues	0.40%	0.40%	0.40%	0.30%
Other (income) expense, percent
Percentage of Sales
Item as a percent of net sales and operating revenues	0.00%	0.00%	0.00%	0.00%
Earnings before income taxes, percent
Percentage of Sales
Item as a percent of net sales and operating revenues	5.50%	5.90%	6.50%	6.50%
Income tax provision, percent
Percentage of Sales
Item as a percent of net sales and operating revenues	1.90%	2.20%	2.40%	2.50%
NET EARNINGS, percent
Percentage of Sales
Item as a percent of net sales and operating revenues	3.60%	3.70%	4.20%	4.00%