Summary of Quarterly Financial Data (Unaudited) (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2025	Sep. 30, 2025	Jun. 30, 2025	Mar. 31, 2025	Dec. 31, 2024	Sep. 30, 2024	Jun. 30, 2024	Mar. 31, 2024	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
Quarterly Financial Information Disclosure [Abstract]
Revenues	$ 7,769.2	$ 8,053.0	$ 8,032.5	$ 7,953.8	$ 8,077.6	$ 7,929.5	$ 8,065.0	$ 7,792.7	$ 31,808.5	$ 31,864.8	$ 30,916.5
Gross profit	1,243.8	1,299.6	1,352.2	1,321.4	1,313.1	1,293.5	1,316.2	1,294.3	5,217.0	5,217.1	5,147.4
Net income	186.7	225.3	267.5	258.4	250.2	239.1	256.5	227.6	937.9	973.4	1,114.2
Net income attributable to Penske Automotive Group common stockholders	$ 186.1	$ 224.8	$ 266.7	$ 257.8	$ 249.3	$ 238.3	$ 254.8	$ 226.5	$ 935.4	$ 968.9	$ 1,108.8
Diluted earnings per share attributable to Penske Automotive Group common stockholders:
Net income per share, Basic (in dollars per share)	$ 2.83	$ 3.41	$ 4.03	$ 3.86					$ 14.13	$ 14.49	$ 16.31
Net income per share, Diluted (in dollars per share)	$ 2.83	$ 3.41	$ 4.03	$ 3.86	$ 3.73	$ 3.57	$ 3.81	$ 3.38	$ 14.13	$ 14.49	$ 16.31