Business Combinations - Pro Forma Information (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Summary of unaudited consolidated pro forma results of operations
Revenues	$ 7,499.2	$ 7,074.4	$ 14,884.2	$ 14,345.6
Net income attributable to Penske Automotive Group common stockholders	$ 301.5	$ 375.9	$ 601.0	$ 749.3
Net income per diluted common share (in dollars per share)	$ 4.42	$ 4.96	$ 8.75	$ 9.79