Inventory (Narrative) (Details) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Inventory Disclosure [Abstract]
Interest credits and advertising assistance	$ 11.5	$ 12.9	$ 36.2	$ 38.5

Floor plan interest credits and advertising assistance received from vendors, which reduce the cost of sales.

No definition available.

Name:	pag_FloorPlanInterestCreditsAndAdvertisingAssistance
Namespace Prefix:	pag_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration