REVENUE RECOGNITION (Disaggregation of Revenue) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Disaggregation of Revenue [Line Items]
Total revenue	$ 3,666.2	$ 3,865.9	$ 10,991.0	$ 11,727.9
New and used vehicle
Disaggregation of Revenue [Line Items]
Total revenue	2,973.6	3,129.9	8,917.8	9,563.4
New and used vehicle | New vehicle
Disaggregation of Revenue [Line Items]
Total revenue	1,861.9	1,799.2	5,572.2	5,519.3
New and used vehicle | Used vehicle retail
Disaggregation of Revenue [Line Items]
Total revenue	1,016.8	1,249.8	3,051.8	3,739.5
New and used vehicle | Used vehicle wholesale
Disaggregation of Revenue [Line Items]
Total revenue	94.9	80.9	293.8	304.6
Parts and service
Disaggregation of Revenue [Line Items]
Total revenue	526.5	536.1	1,568.2	1,558.2
Parts and service | Sale of vehicle parts and accessories
Disaggregation of Revenue [Line Items]
Total revenue	125.1	128.9	375.0	384.5
Parts and service | Vehicle repair and maintenance services
Disaggregation of Revenue [Line Items]
Total revenue	401.4	407.2	1,193.1	1,173.7
Finance and insurance, net
Disaggregation of Revenue [Line Items]
Total revenue	$ 166.1	$ 200.0	$ 505.0	$ 606.4