Revenues - Other Disclosures (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018
Revenues
Total revenues	$ 5,967.6	$ 5,658.6	$ 17,287.8	$ 17,345.8
Commercial Vehicle Distribution and Other
Revenues
Total revenues	119.9	124.8	$ 393.5	429.3
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	26.6		$ 26.6		$ 26.0
Penske Commercial Vehicles Australia | Commercial Vehicle Distribution and Other
Revenues
Payment period			30 days
Total revenues	119.9	123.7	$ 393.5	426.4
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	$ 69.6	$ 65.9	$ 196.5	$ 194.4