Fair Value Measurements - Additional Information (Detail) (Fair Value, Measurements, Nonrecurring)	12 Months Ended
Dec. 31, 2011
Fair Value, Measurements, Nonrecurring
Determination of loss on extinguishment of convertible notes	98.00%

Extinguishment of Debt, Percent of Outstanding Debt

No definition available.

Name:	pva_ExtinguishmentOfDebtPercentOfOutstandingDebt
Namespace Prefix:	pva_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration