Revenue (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Aug. 31, 2020	Aug. 31, 2019	Aug. 31, 2020	Aug. 31, 2019
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	$ 5,372.2	$ 5,201.2	$ 8,600.9	$ 10,567.5
Used vehicle sales
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	4,389.2	4,346.3	7,175.4	8,887.0
Wholesale vehicle sales
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	819.1	678.3	1,161.9	1,340.7
Extended protection plan revenues
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	119.4	113.3	192.8	224.6
Third-party finance fees, net
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	(15.4)	(10.3)	(26.2)	(25.8)
Service revenues
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	26.5	33.4	46.0	67.3
Other
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	33.4	40.2	51.0	73.7
Total other sales and revenues
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	$ 163.9	$ 176.6	$ 263.6	$ 339.8