Revenues - Other Disclosures (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019	Dec. 31, 2019
Revenues
Total revenues	$ 3,651.1	$ 5,755.8	$ 8,660.2	$ 11,320.2
Commercial Vehicle Distribution and Other
Revenues
Total revenues	98.4	132.7	$ 199.5	273.6
Vehicle Sales | Retail Automotive and Retail Commercial Truck Dealership
Revenues
Payment period			30 days
Service and parts | Retail Automotive and Retail Commercial Truck Dealership
Revenues
Payment period			30 days
Finance and insurance, net | Retail Automotive and Retail Commercial Truck Dealership
Revenues
Payment period			30 days
Aggregate reserves relating to chargeback activity	27.4		$ 27.4		$ 26.6
Penske Australia | Commercial Vehicle Distribution and Other
Revenues
Payment period			30 days
Penske Australia | Service and parts | Commercial Vehicle Distribution and Other
Revenues
Total revenues	$ 51.0	$ 69.0	$ 100.9	$ 134.4