Revenues - Retail Automotive Dealership (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Revenues
Total revenues	$ 25,554.7	$ 20,443.9	$ 23,179.4
U.S.
Revenues
Total revenues	15,275.9	12,105.1	13,511.8
Retail automotive dealership
Revenues
Total revenues	22,513.3	17,928.8	20,615.8
Retail automotive dealership | U.S.
Revenues
Total revenues	13,075.8	10,270.3	11,697.6
Retail automotive dealership | U.K.
Revenues
Total revenues	7,984.1	6,344.1	7,559.4
Retail automotive dealership | Germany, Italy, and Japan
Revenues
Total revenues	1,453.4	1,314.4	1,358.8
New vehicle | Retail automotive dealership
Revenues
Total revenues	9,843.2	8,080.5	9,329.5
Used vehicle | Retail automotive dealership
Revenues
Total revenues	8,549.0	6,414.7	7,241.2
Finance and insurance, net | Retail automotive dealership
Revenues
Total revenues	780.5	576.3	652.1
Service and parts | Retail automotive dealership
Revenues
Total revenues	2,165.6	1,883.7	2,195.9
Fleet and wholesale | Retail automotive dealership
Revenues
Total revenues	$ 1,175.0	$ 973.6	$ 1,197.1