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Income Taxes (Details)
3 Months Ended
Mar. 31, 2015
Mar. 31, 2014
Income Tax Disclosure [Abstract]    
Effective tax rate (federal and state combined) 0.20%us-gaap_EffectiveIncomeTaxRateContinuingOperations 42.60%us-gaap_EffectiveIncomeTaxRateContinuingOperations
Federal statutory income tax rate 35.00%us-gaap_EffectiveIncomeTaxRateReconciliationAtFederalStatutoryIncomeTaxRate  
Federal and state (combined) statutory income tax rate 35.70%pva_Federalandstatecombinedstatutoryincometaxrate