Business Combinations - Pro Forma Information (Details) - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024
Business Combination, Asset Acquisition, Transaction between Entities under Common Control, and Joint Venture Formation [Abstract]
Revenues	$ 31,826.8	$ 32,524.1
Net income attributable to Penske Automotive Group common stockholders	$ 936.1	$ 979.8
Net income per diluted common share (in dollars per share)	$ 14.14	$ 14.65