Revenues - Other Disclosures (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020	Dec. 31, 2020
Revenues
Total revenues	$ 6,987.5	$ 3,651.1	$ 12,761.3	$ 8,660.2
Commercial vehicle distribution
Revenues
Total revenues	164.6	98.4	$ 296.8	199.5
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	31.0		$ 31.0		$ 28.7
Penske Australia | Commercial vehicle distribution
Revenues
Payment period			30 days
Penske Australia | Service and parts | Commercial vehicle distribution
Revenues
Total revenues	$ 72.0	$ 51.0	$ 140.0	$ 100.9