Revenues - Other Disclosures (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018	Dec. 31, 2018
Revenues
Total revenues	$ 5,755.8	$ 5,940.3	$ 11,320.2	$ 11,687.2
Commercial Vehicle Distribution and Other
Revenues
Total revenues	132.7	146.0	$ 273.6	304.5
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
Customer return period, parts sales			30 days
Finance and insurance, net | Retail Automotive and Retail Commercial Truck Dealership
Revenues
Payment period			30 days
Aggregate reserves relating to chargeback activity	26.5		$ 26.5		$ 26.0
Penske Commercial Vehicles Australia | Commercial Vehicle Distribution and Other
Revenues
Payment period			30 days
Total revenues	132.7	145.0	$ 273.6	302.7
Penske Power Systems | Commercial Vehicle Distribution and Other
Revenues
Payment period			30 days
Penske Power Systems | Service and parts | Commercial Vehicle Distribution and Other
Revenues
Total revenues	$ 69.0	$ 73.2	$ 134.4	$ 142.4