Intangible Assets (Details) (USD $) In Thousands	6 Months Ended
Jun. 30, 2011
Summary of the changes in the carrying amount of goodwill and franchise value
Goodwill, Beginning Balance	$ 808,488
Goodwill, additions	7,120
Goodwill, foreign currency translation	11,361
Goodwill, Ending Balance	826,969
Franchise value, Beginning Balance	203,401
Franchise value, additions	0
Franchise value, foreign currency translation	2,544
Franchise value, Ending Balance	$ 205,945

Goodwill and franchise value disclosure.

Name:	pag_GoodwillAndFranchiseValueDisclosureAbstract
Namespace Prefix:	pag
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Carrying amount as of the balance sheet date, which is the cumulative amount paid, adjusted for any amortization recognized prior to adoption of FAS 142 and for any impairment charges, in excess of the fair value of net assets acquired in one or more business combination transactions.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 142
-Paragraph 43

+ Details

Name:	us-gaap_Goodwill
Namespace Prefix:	us-gaap
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

The aggregate amount of goodwill acquired in the period and allocated to the reportable segment. The value is stated at fair value based on the purchase price allocation.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 142
-Paragraph 45
-Subparagraph e(1)

+ Details

Name:	us-gaap_GoodwillAcquiredDuringPeriod
Namespace Prefix:	us-gaap
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Reflects net changes to the recorded value of goodwill for foreign currency translation adjustments and purchase accounting adjustments needed to revise the carrying amount of goodwill to fair value.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 142

+ Details

Name:	us-gaap_GoodwillTranslationAndPurchaseAccountingAdjustments
Namespace Prefix:	us-gaap
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

The aggregate amount of indefinite-lived intangible assets acquired in the period and allocated to the reportable segment. The value is stated at fair value based on the purchase price allocation.

+ Details

Name:	us-gaap_IndefiniteLivedIntangibleAssetsAcquiredDuringPeriod
Namespace Prefix:	us-gaap
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Reflects net changes to the recorded value of indefinite-lived intangible assets for foreign currency translation adjustments and purchase accounting adjustments needed to revise the carrying amount of indefinite-lived intangible assets to fair value.

+ Details

Name:	us-gaap_IndefiniteLivedIntangibleAssetsTranslationAndPurchaseAccountingAdjustments
Namespace Prefix:	us-gaap
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Carrying amount (original costs adjusted for previously recognized amortization and impairment) as of the balance sheet date of rights not otherwise specified in the taxonomy having a projected indefinite period of benefit.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 142
-Paragraph 45
-Subparagraph b

+ Details

Name:	us-gaap_OtherIndefiniteLivedIntangibleAssets
Namespace Prefix:	us-gaap
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant