Selected Quarterly Financial Data (Schedule Of Selected Quarterly Financial Data) (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	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
Selected Quarterly Financial Data [Abstract]
Net sales and operating revenues	$ 3,076,283	$ 2,941,407	$ 3,245,552	$ 3,311,057	$ 2,827,948	$ 2,602,446	$ 2,758,004	$ 2,774,420	$ 12,574,299	$ 10,962,818	$ 10,003,599
Gross profit	384,141	381,721	434,743	448,096	369,235	345,219	367,993	381,915	1,648,701	1,464,362	1,378,761
CarMax Auto Finance income	80,821	83,905	84,422	87,019	75,958	72,454	75,676	75,179	336,167	299,267	262,185
Selling, general and administrative expenses	297,454	284,366	283,206	290,189	265,475	257,282	254,674	253,603	1,155,215	1,031,034	940,786
Net earnings	$ 99,209	$ 106,452	$ 140,274	$ 146,651	$ 107,221	$ 94,681	$ 111,636	$ 120,746	$ 492,586	$ 434,284	$ 413,795
Basic net earnings per share	$ 0.45	$ 0.48	$ 0.63	$ 0.65	$ 0.47	$ 0.41	$ 0.49	$ 0.53	$ 2.20	$ 1.90	$ 1.83
Diluted net earnings per share	$ 0.44	$ 0.47	$ 0.62	$ 0.64	$ 0.46	$ 0.41	$ 0.48	$ 0.52	$ 2.16	$ 1.87	$ 1.79