CONSOLIDATED STATEMENTS OF CASH FLOWS (Parenthetical) - USD ($) $ in Millions	6 Months Ended
Jun. 30, 2018	Jun. 30, 2017
CONSOLIDATED CONDENSED STATEMENTS OF CASH FLOWS
Repayment of Sellers' Floor Plan Notes Payable Dealership Acquisitions	$ 25.8	$ 99.0

Repayment of sellers' floor plan notes payable, dealership acquisitions.

No definition available.

Name:	pag_RepaymentOfSellersFloorPlanNotesPayableDealershipAcquisitions
Namespace Prefix:	pag_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration