Inventories (Details Textual) (USD $) In Thousands, unless otherwise specified	12 Months Ended
Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Inventories (Textual) [Abstract]
Interest credits and advertising assistance	$ 29,070	$ 26,166	$ 29,679

Floor Plan Interest Credits and Advertising assistance.

No definition available.

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