Revenues - Other Disclosures (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019
Revenues
Total revenues	$ 5,971.6	$ 5,967.6	$ 14,631.8	$ 17,287.8
Commercial Vehicle Distribution and Other
Revenues
Total revenues	122.7	119.9	$ 322.2	393.5
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	27.8		$ 27.8		$ 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	$ 58.4	$ 69.6	$ 159.2	$ 196.5