Revenue (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
Revenue (Details) - USD ($) $ in Millions	Aug. 31, 2026	Aug. 31, 2025	Aug. 31, 2026	Aug. 31, 2025
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	$ 7,877.9	$ 6,594.7	$ 15,891.4	$ 14,141.2
Used vehicle sales
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	6,310.9	5,270.7	12,702.3	11,374.2
Wholesale vehicle sales
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	1,358.5	1,149.6	2,786.2	2,402.3
Extended protection plan revenues
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	141.6	115.1	275.1	246.8
Third-party finance fees, net
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	(1.8)	(0.8)	(6.3)	(1.5)
Advertising & subscription revenues [Domain]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	36.3	37.9	72.9	74.4
Service revenues
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	26.8	19.2	51.0	38.6
Other
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	5.5	3.0	10.3	6.5
Total other sales and revenues
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	$ 208.4	$ 174.4	$ 403.0	$ 364.8