Revenues - Other Disclosures (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Dec. 31, 2019
Revenues
Aggregate reserves relating to chargeback activity	$ 26.6		$ 26.6
Total revenues	5,009.1	$ 5,564.4
Commercial Vehicle Distribution and Other
Revenues
Total revenues	$ 101.1	140.9
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
Customer return period, parts sales	30 days
Finance and insurance, net | Retail Automotive and Retail Commercial Truck Dealership
Revenues
Payment period	30 days
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	$ 61.5