Discontinued Operations - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	12 Months Ended
Dec. 31, 2010
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Transition services cost	$ 0.7

Disposal Group Including Discontinued Operation Related Transition Service Costs

No definition available.

Name:	pva_DisposalGroupIncludingDiscontinuedOperationRelatedTransitionServiceCosts
Namespace Prefix:	pva_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration