Stock and Stock-Based Incentive Plans Stock And Stock-Based Incentive Plans (Composition of Share-Based Compensation Expense) (Details) - USD ($) $ in Thousands	3 Months Ended
	May 31, 2020	May 31, 2019
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Share-based compensation expense, before income taxes	$ 25,600	$ 45,523
Cost of sales
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Share-based compensation expense, before income taxes	679	2,825
Carmax Auto Finance Income
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Share-based compensation expense, before income taxes	1,270	1,805
Selling, general and administrative expenses
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Share-based compensation expense, before income taxes	$ 23,651	$ 40,893