Share-Based Compensation (Composition Of Share-Based Compensation Expense) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Aug. 31, 2012	Aug. 31, 2011	Aug. 31, 2012	Aug. 31, 2011
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Share-based compensation expense, before income taxes	$ 14,892	$ 11,558	$ 30,709	$ 26,792
Cost Of Sales [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Share-based compensation expense, before income taxes	682	414	1,097	689
CarMax Auto Finance Income [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Share-based compensation expense, before income taxes	651	506	1,129	862
Selling, General And Administrative Expenses [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Share-based compensation expense, before income taxes	$ 13,559	$ 10,638	$ 28,483	$ 25,241