Revenues - Retail Commercial Truck Dealership (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Revenues
Total revenues	$ 5,009.1	$ 5,564.4
Retail Commercial Truck Dealership
Revenues
Total revenues	491.4	332.3
New vehicle | Retail Commercial Truck Dealership
Revenues
Total revenues	318.2	207.4
Used vehicle | Retail Commercial Truck Dealership
Revenues
Total revenues	34.6	24.1
Finance and insurance, net | Retail Commercial Truck Dealership
Revenues
Total revenues	3.2	3.0
Service and parts | Retail Commercial Truck Dealership
Revenues
Total revenues	124.3	91.5
Other | Retail Commercial Truck Dealership
Revenues
Total revenues	$ 11.1	$ 6.3