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Regulatory Matters (Details) (USD $)
 12 Months Ended 1 Months Ended 12 Months Ended 24 Months Ended 1 Months Ended 2 Months Ended
Oct. 31, 2014
Oct. 31, 2013
Oct. 31, 2012
Dec. 31, 1998
Apr. 30, 2014
Dec. 31, 2001
Dec. 31, 2000
Dec. 31, 2001
Nov. 30, 2014
Dec. 31, 2014
May 31, 2012
Oct. 31, 2011
Sep. 30, 2014
Dec. 31, 2014
Jan. 01, 2014
Oct. 31, 2008
Dec. 31, 2013
Aug. 31, 2013
Mar. 01, 2012
Feb. 29, 2012
Public Utilities, Rate Matters, Requested [Abstract]                                        
Public Utilities, Description of Regulatory Scope Our utility operations are regulated by the NCUC, PSCSC and TRA as to rates, service area, adequacy of service, safety standards, extensions and abandonment of facilities, accounting and depreciation. We are also regulated by the NCUC as to the issuance of long-term debt and equity securities. The NCUC and the PSCSC regulate our gas purchasing practices under a standard of prudence and audit our gas cost accounting practices. The TRA regulates our gas purchasing practices under a gas supply incentive program which compares our actual costs to market pricing benchmarks. As part of this jurisdictional oversight, all three regulatory commissions address our gas supply hedging activities. Additionally, all three regulatory commissions allow for recovery of uncollectible gas costs through the PGA. The portion of uncollectibles related to gas costs is recovered through the deferred account and only the non-gas costs, or margin, portion of uncollectibles is included in base rates and uncollectibles expense.                                      
Regulatory Assets $ 213,867,000us-gaap_RegulatoryAssets $ 246,306,000us-gaap_RegulatoryAssets                                    
Regulatory Assets, Current 29,088,000us-gaap_RegulatoryAssetsCurrent 77,204,000us-gaap_RegulatoryAssetsCurrent                                    
Payments to Acquire Property, Plant, and Equipment 460,444,000us-gaap_PaymentsToAcquirePropertyPlantAndEquipment 599,999,000us-gaap_PaymentsToAcquirePropertyPlantAndEquipment 529,576,000us-gaap_PaymentsToAcquirePropertyPlantAndEquipment                                  
Operations and maintenance 270,877,000us-gaap_UtilitiesOperatingExpenseMaintenanceAndOperations 253,120,000us-gaap_UtilitiesOperatingExpenseMaintenanceAndOperations 242,599,000us-gaap_UtilitiesOperatingExpenseMaintenanceAndOperations                                  
Total Amount Of Margin Generated From Secondary Market Activity 97,600,000pny_TotalAmountOfMarginGeneratedFromSecondaryMarketActivity 35,900,000pny_TotalAmountOfMarginGeneratedFromSecondaryMarketActivity 38,700,000pny_TotalAmountOfMarginGeneratedFromSecondaryMarketActivity                                  
Amount Of Net Secondary Market Margins Flowed Through To Jurisdictional Customers 72,200,000pny_AmountOfNetSecondaryMarketMarginsFlowedThroughToJurisdictionalCustomers 26,900,000pny_AmountOfNetSecondaryMarketMarginsFlowedThroughToJurisdictionalCustomers 29,000,000pny_AmountOfNetSecondaryMarketMarginsFlowedThroughToJurisdictionalCustomers                                  
Amount Of Net Secondary Market Margins Retained 25,400,000pny_AmountOfNetSecondaryMarketMarginsRetained 9,000,000pny_AmountOfNetSecondaryMarketMarginsRetained 9,700,000pny_AmountOfNetSecondaryMarketMarginsRetained                                  
North Carolina                                        
Public Utilities, Rate Matters, Requested [Abstract]                                        
North Carolina Bond Issuance Amount       200,000,000pny_StateBondIssuanceAmount
/ us-gaap_StatementGeographicalAxis
= stpr_NC		                                
Capital Investments In Integrity and Safety Projects 241,900,000pny_CapitalInvestmentsInIntegrityandSafetyProjects
/ us-gaap_StatementGeographicalAxis
= stpr_NC		                                      
Tennessee                                        
Public Utilities, Rate Matters, Requested [Abstract]                                        
Capital Investments In Integrity and Safety Projects 54,000,000pny_CapitalInvestmentsInIntegrityandSafetyProjects
/ us-gaap_StatementGeographicalAxis
= stpr_TN		                                      
Deferred operations and maintenance expenses                                        
Public Utilities, Rate Matters, Requested [Abstract]                                        
Regulatory Assets, Current 916,000us-gaap_RegulatoryAssetsCurrent
/ us-gaap_RegulatoryAssetAxis
= pny_DeferredOperationsAndMaintenanceExpensesMember		 739,000us-gaap_RegulatoryAssetsCurrent
/ us-gaap_RegulatoryAssetAxis
= pny_DeferredOperationsAndMaintenanceExpensesMember		                                    
Deferred pipeline integrity expenses                                        
Public Utilities, Rate Matters, Requested [Abstract]                                        
Regulatory Assets, Current 3,470,000us-gaap_RegulatoryAssetsCurrent
/ us-gaap_RegulatoryAssetAxis
= pny_DeferredPipelineIntegrityExpensesMember		 3,149,000us-gaap_RegulatoryAssetsCurrent
/ us-gaap_RegulatoryAssetAxis
= pny_DeferredPipelineIntegrityExpensesMember		                                    
Environmental costs                                        
Public Utilities, Rate Matters, Requested [Abstract]                                        
Regulatory Assets 8,000,000us-gaap_RegulatoryAssets
/ us-gaap_RegulatoryAssetAxis
= us-gaap_EnvironmentalRestorationCostsMember		                                      
Regulatory Assets, Current 1,568,000us-gaap_RegulatoryAssetsCurrent
/ us-gaap_RegulatoryAssetAxis
= us-gaap_EnvironmentalRestorationCostsMember		 1,480,000us-gaap_RegulatoryAssetsCurrent
/ us-gaap_RegulatoryAssetAxis
= us-gaap_EnvironmentalRestorationCostsMember		                                    
Robeson LNG Development Cost [Member]                                        
Public Utilities, Rate Matters, Requested [Abstract]                                        
Regulatory Assets, Current 917,000us-gaap_RegulatoryAssetsCurrent
/ us-gaap_RegulatoryAssetAxis
= pny_RobesonLngDevelopmentCostMember		 382,000us-gaap_RegulatoryAssetsCurrent
/ us-gaap_RegulatoryAssetAxis
= pny_RobesonLngDevelopmentCostMember		                                    
Other Regulatory Assets (Liabilities) [Member]                                        
Public Utilities, Rate Matters, Requested [Abstract]                                        
Regulatory Assets, Current 1,850,000us-gaap_RegulatoryAssetsCurrent
/ us-gaap_RegulatoryAssetAxis
= us-gaap_OtherRegulatoryAssetsLiabilitiesMember		 1,091,000us-gaap_RegulatoryAssetsCurrent
/ us-gaap_RegulatoryAssetAxis
= us-gaap_OtherRegulatoryAssetsLiabilitiesMember		                                    
NCUC [Member]                                        
Public Utilities, Rate Matters, Approved [Abstract]                                        
Public Utilities, Approved Debt Equity Securities Limit, Amount 1,000,000,000pny_PublicUtilitiesApprovedDebtEquitySecuritiesLimitAmount
/ us-gaap_RegulatoryAgencyAxis
= pny_NorthCarolinaUtilitiesCommissionMember		       1,000,000,000pny_PublicUtilitiesApprovedDebtEquitySecuritiesLimitAmount
/ us-gaap_RegulatoryAgencyAxis
= pny_NorthCarolinaUtilitiesCommissionMember		                              
Public Utilities, Rate Matters, Requested [Abstract]                                        
Request Transfer Plant Held For Future Use To Deferred Regulatory Asset     6,700,000pny_RequestTransferPlantHeldForFutureUseToDeferredRegulatoryAsset
/ us-gaap_RegulatoryAgencyAxis
= pny_NorthCarolinaUtilitiesCommissionMember		                                  
Percentage Of Net Secondary Market Margins Flowed Through To Customers 75.00%pny_PercentageOfNetSecondaryMarketMarginsFlowedThroughToCustomers
/ us-gaap_RegulatoryAgencyAxis
= pny_NorthCarolinaUtilitiesCommissionMember		                                      
Percentage Of Net Secondary Market Margins Retained 25.00%pny_PercentageOfNetSecondaryMarketMarginsRetained
/ us-gaap_RegulatoryAgencyAxis
= pny_NorthCarolinaUtilitiesCommissionMember		                                      
NCUC [Member] | Minimum [Member]                                        
Public Utilities, Rate Matters, Requested [Abstract]                                        
Target Percentage Range Normalized Sales 22.50%pny_TargetPercentageNormalizedSales
/ us-gaap_RangeAxis
= us-gaap_MinimumMember
/ us-gaap_RegulatoryAgencyAxis
= pny_NorthCarolinaUtilitiesCommissionMember		                                      
NCUC [Member] | Maximum [Member]                                        
Public Utilities, Rate Matters, Requested [Abstract]                                        
Target Percentage Range Normalized Sales 45.00%pny_TargetPercentageNormalizedSales
/ us-gaap_RangeAxis
= us-gaap_MaximumMember
/ us-gaap_RegulatoryAgencyAxis
= pny_NorthCarolinaUtilitiesCommissionMember		                                      
NCUC [Member] | EasternNC Exclusive Franchise Rights [Member]                                        
Public Utilities, Rate Matters, Requested [Abstract]                                        
North Carolina Bond Issuance Amount           149,600,000pny_StateBondIssuanceAmount
/ us-gaap_PublicUtilitiesRegulatoryProceedingAxis
= pny_EasternNorthCarolinaNaturalGasCompanyExclusiveFranchiseRightsMember
/ us-gaap_RegulatoryAgencyAxis
= pny_NorthCarolinaUtilitiesCommissionMember		 38,700,000pny_StateBondIssuanceAmount
/ us-gaap_PublicUtilitiesRegulatoryProceedingAxis
= pny_EasternNorthCarolinaNaturalGasCompanyExclusiveFranchiseRightsMember
/ us-gaap_RegulatoryAgencyAxis
= pny_NorthCarolinaUtilitiesCommissionMember		 188,300,000pny_StateBondIssuanceAmount
/ us-gaap_PublicUtilitiesRegulatoryProceedingAxis
= pny_EasternNorthCarolinaNaturalGasCompanyExclusiveFranchiseRightsMember
/ us-gaap_RegulatoryAgencyAxis
= pny_NorthCarolinaUtilitiesCommissionMember		                        
Operational Feasibility Assessment Time Period 2 years                                      
NCUC [Member] | General Rate Case Proceeding 2013 [Member]                                        
Public Utilities, Rate Matters, Approved [Abstract]                                        
Overall Rate Base With Approved Rates And Charges                             1,800,000,000pny_OverallRateBaseWithApprovedRatesAndCharges
/ us-gaap_PublicUtilitiesRegulatoryProceedingAxis
= pny_GeneralRateCaseProceeding2013Member
/ us-gaap_RegulatoryAgencyAxis
= pny_NorthCarolinaUtilitiesCommissionMember		          
Public Utilities, Approved Return on Equity, Percentage 10.00%us-gaap_PublicUtilitiesApprovedReturnOnEquityPercentage
/ us-gaap_PublicUtilitiesRegulatoryProceedingAxis
= pny_GeneralRateCaseProceeding2013Member
/ us-gaap_RegulatoryAgencyAxis
= pny_NorthCarolinaUtilitiesCommissionMember		                                      
Public Utilities, Approved Return on Investment, Percentage 7.51%pny_PublicUtilitiesApprovedReturnonInvestmentPercentage
/ us-gaap_PublicUtilitiesRegulatoryProceedingAxis
= pny_GeneralRateCaseProceeding2013Member
/ us-gaap_RegulatoryAgencyAxis
= pny_NorthCarolinaUtilitiesCommissionMember		                                      
Public Utilities, Approved Equity Capital Structure, Percentage 50.70%us-gaap_PublicUtilitiesApprovedEquityCapitalStructurePercentage
/ us-gaap_PublicUtilitiesRegulatoryProceedingAxis
= pny_GeneralRateCaseProceeding2013Member
/ us-gaap_RegulatoryAgencyAxis
= pny_NorthCarolinaUtilitiesCommissionMember		                                      
Approved Annual Average Revenue Percentage Increase From Last Rate Case 0.70%pny_ApprovedAnnualAverageRevenuePercentageIncreaseFromLastRateCase
/ us-gaap_PublicUtilitiesRegulatoryProceedingAxis
= pny_GeneralRateCaseProceeding2013Member
/ us-gaap_RegulatoryAgencyAxis
= pny_NorthCarolinaUtilitiesCommissionMember		                                      
NCUC [Member] | General Rate Case Proceeding 2013 [Member] | Sales [Member]                                        
Public Utilities, Rate Matters, Approved [Abstract]                                        
Public Utilities, Approved Rate Increase (Decrease), Amount 30,700,000us-gaap_PublicUtilitiesApprovedRateIncreaseDecreaseAmount
/ us-gaap_IncomeStatementLocationAxis
= us-gaap_SalesMember
/ us-gaap_PublicUtilitiesRegulatoryProceedingAxis
= pny_GeneralRateCaseProceeding2013Member
/ us-gaap_RegulatoryAgencyAxis
= pny_NorthCarolinaUtilitiesCommissionMember		                                      
Public Utilities, Approved Rate Increase (Decrease), Percentage 3.58%us-gaap_PublicUtilitiesApprovedRateIncreaseDecreasePercentage
/ us-gaap_IncomeStatementLocationAxis
= us-gaap_SalesMember
/ us-gaap_PublicUtilitiesRegulatoryProceedingAxis
= pny_GeneralRateCaseProceeding2013Member
/ us-gaap_RegulatoryAgencyAxis
= pny_NorthCarolinaUtilitiesCommissionMember		                                      
NCUC [Member] | General Rate Case Proceeding 2013 [Member] | Sales [Member] | Gas Utility Margin [Member]                                        
Public Utilities, Rate Matters, Approved [Abstract]                                        
Public Utilities, Approved Rate Increase (Decrease), Amount 16,800,000us-gaap_PublicUtilitiesApprovedRateIncreaseDecreaseAmount
/ pny_ComponentsOfRevenueIncreaseAxis
= pny_GasUtilityMarginMember
/ us-gaap_IncomeStatementLocationAxis
= us-gaap_SalesMember
/ us-gaap_PublicUtilitiesRegulatoryProceedingAxis
= pny_GeneralRateCaseProceeding2013Member
/ us-gaap_RegulatoryAgencyAxis
= pny_NorthCarolinaUtilitiesCommissionMember		                                      
NCUC [Member] | General Rate Case Proceeding 2013 [Member] | Sales [Member] | Fixed Gas Costs [Member]                                        
Public Utilities, Rate Matters, Approved [Abstract]                                        
Public Utilities, Approved Rate Increase (Decrease), Amount 13,800,000us-gaap_PublicUtilitiesApprovedRateIncreaseDecreaseAmount
/ pny_ComponentsOfRevenueIncreaseAxis
= pny_FixedGasCostsMember
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= us-gaap_SalesMember
/ us-gaap_PublicUtilitiesRegulatoryProceedingAxis
= pny_GeneralRateCaseProceeding2013Member
/ us-gaap_RegulatoryAgencyAxis
= pny_NorthCarolinaUtilitiesCommissionMember		                                      
NCUC [Member] | General Rate Case Proceeding 2013 [Member] | Revised Pre-Tax Income [Member]                                        
Public Utilities, Rate Matters, Approved [Abstract]                                        
Public Utilities, Approved Rate Increase (Decrease), Amount 24,200,000us-gaap_PublicUtilitiesApprovedRateIncreaseDecreaseAmount
/ us-gaap_IncomeStatementLocationAxis
= pny_RevisedPreTaxIncomeMember
/ us-gaap_PublicUtilitiesRegulatoryProceedingAxis
= pny_GeneralRateCaseProceeding2013Member
/ us-gaap_RegulatoryAgencyAxis
= pny_NorthCarolinaUtilitiesCommissionMember		                                      
NCUC [Member] | General Rate Case Proceeding 2013 [Member] | Operating Expense [Member]                                        
Public Utilities, Rate Matters, Approved [Abstract]                                        
Public Utilities, Approved Rate Increase (Decrease), Amount (10,900,000)us-gaap_PublicUtilitiesApprovedRateIncreaseDecreaseAmount
/ us-gaap_IncomeStatementLocationAxis
= us-gaap_OperatingExpenseMember
/ us-gaap_PublicUtilitiesRegulatoryProceedingAxis
= pny_GeneralRateCaseProceeding2013Member
/ us-gaap_RegulatoryAgencyAxis
= pny_NorthCarolinaUtilitiesCommissionMember		                                      
NCUC [Member] | North Carolina Public Staff Audit 2011 Gas Cost Review Period [Member]                                        
Public Utilities, Rate Matters, Approved [Abstract]                                        
Percentage Of Allowed Recovery For Gas Costs 100.00%pny_PercentageOfAllowedRecoveryForGasCosts
/ us-gaap_PublicUtilitiesRegulatoryProceedingAxis
= pny_NorthCarolinaPublicStaffAudit2011GasCostReviewPeriodMember
/ us-gaap_RegulatoryAgencyAxis
= pny_NorthCarolinaUtilitiesCommissionMember		                                      
NCUC [Member] | North Carolina Public Staff Audit 2012 Gas Cost Review Period [Member]                                        
Public Utilities, Rate Matters, Approved [Abstract]                                        
Percentage Of Allowed Recovery For Gas Costs 100.00%pny_PercentageOfAllowedRecoveryForGasCosts
/ us-gaap_PublicUtilitiesRegulatoryProceedingAxis
= pny_NorthCarolinaPublicStaffAudit2012GasCostReviewPeriodMember
/ us-gaap_RegulatoryAgencyAxis
= pny_NorthCarolinaUtilitiesCommissionMember		                                      
NCUC [Member] | North Carolina Public Staff Audit 2013 Gas Cost Review Period [Member]                                        
Public Utilities, Rate Matters, Approved [Abstract]                                        
Percentage Of Allowed Recovery For Gas Costs 100.00%pny_PercentageOfAllowedRecoveryForGasCosts
/ us-gaap_PublicUtilitiesRegulatoryProceedingAxis
= pny_NorthCarolinaPublicStaffAudit2013GasCostReviewPeriodMember
/ us-gaap_RegulatoryAgencyAxis
= pny_NorthCarolinaUtilitiesCommissionMember		                                      
NCUC [Member] | North Carolina Public Staff Audit 2013 Gas Cost Review Period [Member] | Subsequent Event [Member]                                        
Public Utilities, Rate Matters, Requested [Abstract]                                        
Public Utilities, Disclosure of Rate Matters                 In November 2014, the NCUC approved our accounting of gas costs for the twelve months ended May 31, 2014. We were deemed prudent on our gas purchasing policies and practices during this review period and allowed 100% recovery.                      
NCUC [Member] | North Carolina Public Staff Audit 2014 Gas Cost Review Period [Member] | Subsequent Event [Member]                                        
Public Utilities, Rate Matters, Approved [Abstract]                                        
Percentage Of Allowed Recovery For Gas Costs                 100.00%pny_PercentageOfAllowedRecoveryForGasCosts
/ us-gaap_PublicUtilitiesRegulatoryProceedingAxis
= pny_NorthCarolinaPublicStaffAudit2014GasCostReviewPeriodMember
/ us-gaap_RegulatoryAgencyAxis
= pny_NorthCarolinaUtilitiesCommissionMember
/ us-gaap_SubsequentEventTypeAxis
= us-gaap_SubsequentEventMember		                      
NCUC [Member] | North Carolina IMR Adjustment 2014 [Member]                                        
Public Utilities, Rate Matters, Approved [Abstract]                                        
Public Utilities, Approved Rate Increase (Decrease), Amount 800,000us-gaap_PublicUtilitiesApprovedRateIncreaseDecreaseAmount
/ us-gaap_PublicUtilitiesRegulatoryProceedingAxis
= pny_NorthCarolinaApprovalIMRAdjustmentFebruary2014Member
/ us-gaap_RegulatoryAgencyAxis
= pny_NorthCarolinaUtilitiesCommissionMember		                                      
NCUC [Member] | NCUC Petition for IMR Rate Adjustment Filed December 2014 [Member] | Subsequent Event [Member]                                        
Public Utilities, Rate Matters, Requested [Abstract]                                        
Public Utilities, Requested Rate Increase (Decrease), Amount                   26,600,000us-gaap_PublicUtilitiesRequestedRateIncreaseDecreaseAmount
/ us-gaap_PublicUtilitiesRegulatoryProceedingAxis
= pny_NCUCPetitionFiledIMRDecember2014Member
/ us-gaap_RegulatoryAgencyAxis
= pny_NorthCarolinaUtilitiesCommissionMember
/ us-gaap_SubsequentEventTypeAxis
= us-gaap_SubsequentEventMember		                    
Public Utilities, Disclosure of Rate Matters                   In December 2014, we filed a petition with the NCUC seeking authority to adjust rates to collect an additional $26.6 million in annual IMR margin revenues effective February 1, 2015 based on $241.9 million of capital investments in integrity and safety projects over the twelve-month period ending October 31, 2014. We are waiting on a ruling from the NCUC at this time.                    
NCUC [Member] | NCUC Petition for Limited Waiver 2014 [Member]                                        
Public Utilities, Rate Matters, Requested [Abstract]                                        
Operations and maintenance 65,000us-gaap_UtilitiesOperatingExpenseMaintenanceAndOperations
/ us-gaap_PublicUtilitiesRegulatoryProceedingAxis
= pny_NCUCPetitionforLimitedWaiver2014Member
/ us-gaap_RegulatoryAgencyAxis
= pny_NorthCarolinaUtilitiesCommissionMember		                                      
NCUC [Member] | Deferred operations and maintenance expenses                                        
Public Utilities, Rate Matters, Approved [Abstract]                                        
Deferral Time Period Of Operation And Maintenance Expense 8 years                                      
Public Utilities, Rate Matters, Requested [Abstract]                                        
Regulatory Assets 5,600,000us-gaap_RegulatoryAssets
/ us-gaap_RegulatoryAgencyAxis
= pny_NorthCarolinaUtilitiesCommissionMember
/ us-gaap_RegulatoryAssetAxis
= pny_DeferredOperationsAndMaintenanceExpensesMember		 6,400,000us-gaap_RegulatoryAssets
/ us-gaap_RegulatoryAgencyAxis
= pny_NorthCarolinaUtilitiesCommissionMember
/ us-gaap_RegulatoryAssetAxis
= pny_DeferredOperationsAndMaintenanceExpensesMember		                                    
NCUC [Member] | Deferred operations and maintenance expenses | General Rate Case Proceeding 2008 [Member]                                        
Public Utilities, Rate Matters, Approved [Abstract]                                        
Interest Accrued On Deferred Expenses 7.84%pny_InterestAccruedOnDeferredExpenses
/ us-gaap_PublicUtilitiesRegulatoryProceedingAxis
= pny_Generalratecaseproceeding2008Member
/ us-gaap_RegulatoryAgencyAxis
= pny_NorthCarolinaUtilitiesCommissionMember
/ us-gaap_RegulatoryAssetAxis
= pny_DeferredOperationsAndMaintenanceExpensesMember		                                      
Amortization Time Period For Specified Expenses 12 years                                      
Public Utilities, Rate Matters, Requested [Abstract]                                        
Regulatory Assets                               9,000,000us-gaap_RegulatoryAssets
/ us-gaap_PublicUtilitiesRegulatoryProceedingAxis
= pny_Generalratecaseproceeding2008Member
/ us-gaap_RegulatoryAgencyAxis
= pny_NorthCarolinaUtilitiesCommissionMember
/ us-gaap_RegulatoryAssetAxis
= pny_DeferredOperationsAndMaintenanceExpensesMember		        
NCUC [Member] | Deferred operations and maintenance expenses | General Rate Case Proceeding 2013 [Member]                                        
Public Utilities, Rate Matters, Approved [Abstract]                                        
Interest Accrued On Deferred Expenses 6.55%pny_InterestAccruedOnDeferredExpenses
/ us-gaap_PublicUtilitiesRegulatoryProceedingAxis
= pny_GeneralRateCaseProceeding2013Member
/ us-gaap_RegulatoryAgencyAxis
= pny_NorthCarolinaUtilitiesCommissionMember
/ us-gaap_RegulatoryAssetAxis
= pny_DeferredOperationsAndMaintenanceExpensesMember		                                      
Amortization Time Period For Specified Expenses 82 months                                      
Regulatory Noncurrent Asset, End Date for Recovery Oct. 31, 2020                                      
Public Utilities, Rate Matters, Requested [Abstract]                                        
Regulatory Assets                                 6,300,000us-gaap_RegulatoryAssets
/ us-gaap_PublicUtilitiesRegulatoryProceedingAxis
= pny_GeneralRateCaseProceeding2013Member
/ us-gaap_RegulatoryAgencyAxis
= pny_NorthCarolinaUtilitiesCommissionMember
/ us-gaap_RegulatoryAssetAxis
= pny_DeferredOperationsAndMaintenanceExpensesMember		      
NCUC [Member] | Deferred pipeline integrity expenses                                        
Public Utilities, Rate Matters, Requested [Abstract]                                        
Regulatory Assets 28,200,000us-gaap_RegulatoryAssets
/ us-gaap_RegulatoryAgencyAxis
= pny_NorthCarolinaUtilitiesCommissionMember
/ us-gaap_RegulatoryAssetAxis
= pny_DeferredPipelineIntegrityExpensesMember		 19,400,000us-gaap_RegulatoryAssets
/ us-gaap_RegulatoryAgencyAxis
= pny_NorthCarolinaUtilitiesCommissionMember
/ us-gaap_RegulatoryAssetAxis
= pny_DeferredPipelineIntegrityExpensesMember		                                    
NCUC [Member] | Deferred pipeline integrity expenses | General Rate Case Proceeding 2013 [Member]                                        
Public Utilities, Rate Matters, Approved [Abstract]                                        
Amortization Time Period For Specified Expenses 5 years                                      
Regulatory Noncurrent Asset, End Date for Recovery Dec. 31, 2018                                      
Public Utilities, Rate Matters, Requested [Abstract]                                        
Regulatory Assets                                   17,300,000us-gaap_RegulatoryAssets
/ us-gaap_PublicUtilitiesRegulatoryProceedingAxis
= pny_GeneralRateCaseProceeding2013Member
/ us-gaap_RegulatoryAgencyAxis
= pny_NorthCarolinaUtilitiesCommissionMember
/ us-gaap_RegulatoryAssetAxis
= pny_DeferredPipelineIntegrityExpensesMember		    
NCUC [Member] | Environmental costs | General Rate Case Proceeding 2013 [Member]                                        
Public Utilities, Rate Matters, Approved [Abstract]                                        
Amortization Time Period For Specified Expenses 5 years                                      
Regulatory Noncurrent Asset, End Date for Recovery Dec. 31, 2018                                      
Public Utilities, Rate Matters, Requested [Abstract]                                        
Regulatory Assets                                 6,300,000us-gaap_RegulatoryAssets
/ us-gaap_PublicUtilitiesRegulatoryProceedingAxis
= pny_GeneralRateCaseProceeding2013Member
/ us-gaap_RegulatoryAgencyAxis
= pny_NorthCarolinaUtilitiesCommissionMember
/ us-gaap_RegulatoryAssetAxis
= us-gaap_EnvironmentalRestorationCostsMember		      
NCUC [Member] | Robeson LNG Development Cost [Member] | General Rate Case Proceeding 2013 [Member]                                        
Public Utilities, Rate Matters, Requested [Abstract]                                        
Regulatory Assets                                 1,200,000us-gaap_RegulatoryAssets
/ us-gaap_PublicUtilitiesRegulatoryProceedingAxis
= pny_GeneralRateCaseProceeding2013Member
/ us-gaap_RegulatoryAgencyAxis
= pny_NorthCarolinaUtilitiesCommissionMember
/ us-gaap_RegulatoryAssetAxis
= pny_RobesonLngDevelopmentCostMember		      
NCUC [Member] | Robeson LNG Development Cost [Member] | General Rate Application Settlement 2013 [Member]                                        
Public Utilities, Rate Matters, Approved [Abstract]                                        
Amortization Time Period For Specified Expenses 38 months                                      
Regulatory Noncurrent Asset, End Date for Recovery Feb. 28, 2017                                      
Public Utilities, Rate Matters, Requested [Abstract]                                        
Regulatory Assets                                 1,200,000us-gaap_RegulatoryAssets
/ us-gaap_PublicUtilitiesRegulatoryProceedingAxis
= pny_GeneralRateApplicationSettlement2013Member
/ us-gaap_RegulatoryAgencyAxis
= pny_NorthCarolinaUtilitiesCommissionMember
/ us-gaap_RegulatoryAssetAxis
= pny_RobesonLngDevelopmentCostMember		      
PSCSC [Member]                                        
Public Utilities, Rate Matters, Requested [Abstract]                                        
Percentage Of Net Secondary Market Margins Flowed Through To Customers 75.00%pny_PercentageOfNetSecondaryMarketMarginsFlowedThroughToCustomers
/ us-gaap_RegulatoryAgencyAxis
= pny_PublicServiceCommissionofSouthCarolinaMember		                                      
Percentage Of Net Secondary Market Margins Retained 25.00%pny_PercentageOfNetSecondaryMarketMarginsRetained
/ us-gaap_RegulatoryAgencyAxis
= pny_PublicServiceCommissionofSouthCarolinaMember		                                      
Maximum Utility Rate of Return Change Allowed Under RSA 50pny_MaximumUtilityRateofReturnChangeAllowedUnderRSA
/ us-gaap_RegulatoryAgencyAxis
= pny_PublicServiceCommissionofSouthCarolinaMember		                                      
PSCSC [Member] | Minimum [Member]                                        
Public Utilities, Rate Matters, Requested [Abstract]                                        
Target Percentage Range Normalized Sales 22.50%pny_TargetPercentageNormalizedSales
/ us-gaap_RangeAxis
= us-gaap_MinimumMember
/ us-gaap_RegulatoryAgencyAxis
= pny_PublicServiceCommissionofSouthCarolinaMember		                                      
PSCSC [Member] | Maximum [Member]                                        
Public Utilities, Rate Matters, Requested [Abstract]                                        
Target Percentage Range Normalized Sales 45.00%pny_TargetPercentageNormalizedSales
/ us-gaap_RangeAxis
= us-gaap_MaximumMember
/ us-gaap_RegulatoryAgencyAxis
= pny_PublicServiceCommissionofSouthCarolinaMember		                                      
PSCSC [Member] | Settlement With Office Of Regulatory Staff October 2012 [Member]                                        
Public Utilities, Rate Matters, Approved [Abstract]                                        
Public Utilities, Approved Return on Equity, Percentage 11.30%us-gaap_PublicUtilitiesApprovedReturnOnEquityPercentage
/ us-gaap_PublicUtilitiesRegulatoryProceedingAxis
= pny_SettlementWithOfficeOfRegulatoryStaffOctober2012Member
/ us-gaap_RegulatoryAgencyAxis
= pny_PublicServiceCommissionofSouthCarolinaMember		                                      
PSCSC [Member] | Settlement With Office Of Regulatory Staff October 2012 [Member] | Margin [Member]                                        
Public Utilities, Rate Matters, Approved [Abstract]                                        
Public Utilities, Approved Rate Increase (Decrease), Amount (1,100,000)us-gaap_PublicUtilitiesApprovedRateIncreaseDecreaseAmount
/ us-gaap_IncomeStatementLocationAxis
= pny_MarginMember
/ us-gaap_PublicUtilitiesRegulatoryProceedingAxis
= pny_SettlementWithOfficeOfRegulatoryStaffOctober2012Member
/ us-gaap_RegulatoryAgencyAxis
= pny_PublicServiceCommissionofSouthCarolinaMember		                                      
PSCSC [Member] | Settlement With Office Of Regulatory Staff October 2013 [Member]                                        
Public Utilities, Rate Matters, Approved [Abstract]                                        
Public Utilities, Approved Return on Equity, Percentage 11.30%us-gaap_PublicUtilitiesApprovedReturnOnEquityPercentage
/ us-gaap_PublicUtilitiesRegulatoryProceedingAxis
= pny_SettlementWithOfficeOfRegulatoryStaffOctober2013Member
/ us-gaap_RegulatoryAgencyAxis
= pny_PublicServiceCommissionofSouthCarolinaMember		                                      
PSCSC [Member] | Settlement With Office Of Regulatory Staff October 2013 [Member] | Margin [Member]                                        
Public Utilities, Rate Matters, Approved [Abstract]                                        
Public Utilities, Approved Rate Increase (Decrease), Amount (100,000)us-gaap_PublicUtilitiesApprovedRateIncreaseDecreaseAmount
/ us-gaap_IncomeStatementLocationAxis
= pny_MarginMember
/ us-gaap_PublicUtilitiesRegulatoryProceedingAxis
= pny_SettlementWithOfficeOfRegulatoryStaffOctober2013Member
/ us-gaap_RegulatoryAgencyAxis
= pny_PublicServiceCommissionofSouthCarolinaMember		                                      
PSCSC [Member] | Settlement With Office of Regulatory Staff October 2014 [Member]                                        
Public Utilities, Rate Matters, Approved [Abstract]                                        
Public Utilities, Approved Return on Equity, Percentage 10.20%us-gaap_PublicUtilitiesApprovedReturnOnEquityPercentage
/ us-gaap_PublicUtilitiesRegulatoryProceedingAxis
= pny_SettlementWithOfficeofRegulatoryStaffOctober2014Member
/ us-gaap_RegulatoryAgencyAxis
= pny_PublicServiceCommissionofSouthCarolinaMember		                                      
PSCSC [Member] | Settlement With Office of Regulatory Staff October 2014 [Member] | Margin [Member]                                        
Public Utilities, Rate Matters, Approved [Abstract]                                        
Public Utilities, Approved Rate Increase (Decrease), Amount (2,900,000)us-gaap_PublicUtilitiesApprovedRateIncreaseDecreaseAmount
/ us-gaap_IncomeStatementLocationAxis
= pny_MarginMember
/ us-gaap_PublicUtilitiesRegulatoryProceedingAxis
= pny_SettlementWithOfficeofRegulatoryStaffOctober2014Member
/ us-gaap_RegulatoryAgencyAxis
= pny_PublicServiceCommissionofSouthCarolinaMember		                                      
PSCSC [Member] | Environmental costs | Settlement With Office Of Regulatory Staff October 2013 [Member]                                        
Public Utilities, Rate Matters, Approved [Abstract]                                        
Amortization Time Period For Specified Expenses 1 year                                      
Regulatory Noncurrent Asset, End Date for Recovery Oct. 31, 2014                                      
Public Utilities, Rate Matters, Requested [Abstract]                                        
Regulatory Assets, Current   200,000us-gaap_RegulatoryAssetsCurrent
/ us-gaap_PublicUtilitiesRegulatoryProceedingAxis
= pny_SettlementWithOfficeOfRegulatoryStaffOctober2013Member
/ us-gaap_RegulatoryAgencyAxis
= pny_PublicServiceCommissionofSouthCarolinaMember
/ us-gaap_RegulatoryAssetAxis
= us-gaap_EnvironmentalRestorationCostsMember		                                    
PSCSC [Member] | Environmental costs | Settlement With Office of Regulatory Staff October 2014 [Member]                                        
Public Utilities, Rate Matters, Approved [Abstract]                                        
Amortization Time Period For Specified Expenses 1 year                                      
Regulatory Noncurrent Asset, End Date for Recovery Oct. 31, 2015                                      
Public Utilities, Rate Matters, Requested [Abstract]                                        
Regulatory Assets 100,000us-gaap_RegulatoryAssets
/ us-gaap_PublicUtilitiesRegulatoryProceedingAxis
= pny_SettlementWithOfficeofRegulatoryStaffOctober2014Member
/ us-gaap_RegulatoryAgencyAxis
= pny_PublicServiceCommissionofSouthCarolinaMember
/ us-gaap_RegulatoryAssetAxis
= us-gaap_EnvironmentalRestorationCostsMember		                                      
Regulatory Assets, Current 100,000us-gaap_RegulatoryAssetsCurrent
/ us-gaap_PublicUtilitiesRegulatoryProceedingAxis
= pny_SettlementWithOfficeofRegulatoryStaffOctober2014Member
/ us-gaap_RegulatoryAgencyAxis
= pny_PublicServiceCommissionofSouthCarolinaMember
/ us-gaap_RegulatoryAssetAxis
= us-gaap_EnvironmentalRestorationCostsMember		                                      
PSCSC [Member] | Robeson LNG Development Cost [Member] | Settlement With Office of Regulatory Staff October 2014 [Member]                                        
Public Utilities, Rate Matters, Approved [Abstract]                                        
Amortization Time Period For Specified Expenses 12 months                                      
Regulatory Noncurrent Asset, End Date for Recovery Oct. 31, 2015                                      
Public Utilities, Rate Matters, Requested [Abstract]                                        
Regulatory Assets, Current 500,000us-gaap_RegulatoryAssetsCurrent
/ us-gaap_PublicUtilitiesRegulatoryProceedingAxis
= pny_SettlementWithOfficeofRegulatoryStaffOctober2014Member
/ us-gaap_RegulatoryAgencyAxis
= pny_PublicServiceCommissionofSouthCarolinaMember
/ us-gaap_RegulatoryAssetAxis
= pny_RobesonLngDevelopmentCostMember		                                      
Tennessee Regulatory Authority [Member]                                        
Public Utilities, Rate Matters, Requested [Abstract]                                        
Percentage Of Net Secondary Market Margins Flowed Through To Customers 75.00%pny_PercentageOfNetSecondaryMarketMarginsFlowedThroughToCustomers
/ us-gaap_RegulatoryAgencyAxis
= pny_TennesseeRegulatoryAuthorityMember		                                      
Percentage Of Net Secondary Market Margins Retained 25.00%pny_PercentageOfNetSecondaryMarketMarginsRetained
/ us-gaap_RegulatoryAgencyAxis
= pny_TennesseeRegulatoryAuthorityMember		                                      
Annual Incentive Cap On Gains And Losses 1,600,000.0pny_AnnualIncentiveCapOnGainsAndLosses
/ us-gaap_RegulatoryAgencyAxis
= pny_TennesseeRegulatoryAuthorityMember		                                      
Tennessee Regulatory Authority [Member] | Collection Nashville Franchise Fee [Member]                                        
Public Utilities, Rate Matters, Approved [Abstract]                                        
Denied Franchise Fees                       1,500,000pny_DeniedFranchiseFees
/ us-gaap_PublicUtilitiesRegulatoryProceedingAxis
= pny_CollectionNashvilleFranchiseFeeMember
/ us-gaap_RegulatoryAgencyAxis
= pny_TennesseeRegulatoryAuthorityMember		                
Public Utilities, Rate Matters, Requested [Abstract]                                        
Public Utilities, Requested Rate Increase (Decrease), Amount 2,900,000us-gaap_PublicUtilitiesRequestedRateIncreaseDecreaseAmount
/ us-gaap_PublicUtilitiesRegulatoryProceedingAxis
= pny_CollectionNashvilleFranchiseFeeMember
/ us-gaap_RegulatoryAgencyAxis
= pny_TennesseeRegulatoryAuthorityMember		                                      
Operations and maintenance                     (500,000)us-gaap_UtilitiesOperatingExpenseMaintenanceAndOperations
/ us-gaap_PublicUtilitiesRegulatoryProceedingAxis
= pny_CollectionNashvilleFranchiseFeeMember
/ us-gaap_RegulatoryAgencyAxis
= pny_TennesseeRegulatoryAuthorityMember		 1,500,000us-gaap_UtilitiesOperatingExpenseMaintenanceAndOperations
/ us-gaap_PublicUtilitiesRegulatoryProceedingAxis
= pny_CollectionNashvilleFranchiseFeeMember
/ us-gaap_RegulatoryAgencyAxis
= pny_TennesseeRegulatoryAuthorityMember		                
Tennessee Regulatory Authority [Member] | Actual Cost Adjustment [Member] | Subsequent Event [Member]                                        
Public Utilities, Rate Matters, Requested [Abstract]                                        
Public Utilities, Disclosure of Rate Matters                   In December 2014, we filed an annual report for the twelve months ended June 30, 2013 with the TRA that reflected the transactions in the deferred gas cost account for the ACA mechanism. We are waiting on a ruling from the TRA at this time.                    
Tennessee Regulatory Authority [Member] | Adjustment Filed August 2013 [Member]                                        
Public Utilities, Rate Matters, Requested [Abstract]                                        
Public Utilities, Requested Rate Increase (Decrease), Amount 3,700,000us-gaap_PublicUtilitiesRequestedRateIncreaseDecreaseAmount
/ us-gaap_PublicUtilitiesRegulatoryProceedingAxis
= pny_AdjustmentFiledAugust2013Member
/ us-gaap_RegulatoryAgencyAxis
= pny_TennesseeRegulatoryAuthorityMember		                                      
Expense Related to Actual Cost Adjustment                         1,700,000pny_ExpenseRelatedtoActualCostAdjustment
/ us-gaap_PublicUtilitiesRegulatoryProceedingAxis
= pny_AdjustmentFiledAugust2013Member
/ us-gaap_RegulatoryAgencyAxis
= pny_TennesseeRegulatoryAuthorityMember		              
Tennessee Regulatory Authority [Member] | TRA Settlement December 2014 [Member] | Subsequent Event [Member]                                        
Public Utilities, Rate Matters, Approved [Abstract]                                        
Public Utilities, Approved Rate Increase (Decrease), Amount                           2,000,000us-gaap_PublicUtilitiesApprovedRateIncreaseDecreaseAmount
/ us-gaap_PublicUtilitiesRegulatoryProceedingAxis
= pny_TRASettlementDecember2014Member
/ us-gaap_RegulatoryAgencyAxis
= pny_TennesseeRegulatoryAuthorityMember
/ us-gaap_SubsequentEventTypeAxis
= us-gaap_SubsequentEventMember		            
Public Utilities, Rate Matters, Requested [Abstract]                                        
Public Utilities, Disclosure of Rate Matters                           In November 2014, we filed a joint settlement agreement with the TRA and the Tennessee Attorney General's Consumer Advocate and Protection Division (CAD) in which the parties agreed that we may include in our next ACA filing prior period adjustments totaling $2 million in lieu of the $3.7 million as originally petitioned. In December 2014, the TRA approved the settlement agreement, and we included the stipulated $2 million of prior period adjustments in the filed ACA annual report for the twelve-month period ended June 30, 2013.            
Tennessee Regulatory Authority [Member] | General Rate Application Settlement 2012 [Member]                                        
Public Utilities, Rate Matters, Approved [Abstract]                                        
Public Utilities, Approved Return on Equity, Percentage 10.20%us-gaap_PublicUtilitiesApprovedReturnOnEquityPercentage
/ us-gaap_PublicUtilitiesRegulatoryProceedingAxis
= pny_GeneralRateApplicationSettlement2012Member
/ us-gaap_RegulatoryAgencyAxis
= pny_TennesseeRegulatoryAuthorityMember		                                      
Public Utilities, Rate Matters, Requested [Abstract]                                        
Recovery Of Fixed Charges Cost Allocations                                     37.00%pny_RecoveryOfFixedChargesCostAllocations
/ us-gaap_PublicUtilitiesRegulatoryProceedingAxis
= pny_GeneralRateApplicationSettlement2012Member
/ us-gaap_RegulatoryAgencyAxis
= pny_TennesseeRegulatoryAuthorityMember		 29.00%pny_RecoveryOfFixedChargesCostAllocations
/ us-gaap_PublicUtilitiesRegulatoryProceedingAxis
= pny_GeneralRateApplicationSettlement2012Member
/ us-gaap_RegulatoryAgencyAxis
= pny_TennesseeRegulatoryAuthorityMember
Recovery Of Volumetric Charges Cost Allocations                                     63.00%pny_RecoveryOfVolumetricChargesCostAllocations
/ us-gaap_PublicUtilitiesRegulatoryProceedingAxis
= pny_GeneralRateApplicationSettlement2012Member
/ us-gaap_RegulatoryAgencyAxis
= pny_TennesseeRegulatoryAuthorityMember		 71.00%pny_RecoveryOfVolumetricChargesCostAllocations
/ us-gaap_PublicUtilitiesRegulatoryProceedingAxis
= pny_GeneralRateApplicationSettlement2012Member
/ us-gaap_RegulatoryAgencyAxis
= pny_TennesseeRegulatoryAuthorityMember
Tennessee Regulatory Authority [Member] | General Rate Application Settlement 2012 [Member] | Sales [Member]                                        
Public Utilities, Rate Matters, Approved [Abstract]                                        
Public Utilities, Approved Rate Increase (Decrease), Amount 11,900,000us-gaap_PublicUtilitiesApprovedRateIncreaseDecreaseAmount
/ us-gaap_IncomeStatementLocationAxis
= us-gaap_SalesMember
/ us-gaap_PublicUtilitiesRegulatoryProceedingAxis
= pny_GeneralRateApplicationSettlement2012Member
/ us-gaap_RegulatoryAgencyAxis
= pny_TennesseeRegulatoryAuthorityMember		                                      
Public Utilities, Approved Rate Increase (Decrease), Percentage 6.30%us-gaap_PublicUtilitiesApprovedRateIncreaseDecreasePercentage
/ us-gaap_IncomeStatementLocationAxis
= us-gaap_SalesMember
/ us-gaap_PublicUtilitiesRegulatoryProceedingAxis
= pny_GeneralRateApplicationSettlement2012Member
/ us-gaap_RegulatoryAgencyAxis
= pny_TennesseeRegulatoryAuthorityMember		                                      
Tennessee Regulatory Authority [Member] | Tennessee IMR Petition August 2013 [Member]                                        
Public Utilities, Rate Matters, Requested [Abstract]                                        
Public Utilities, Requested Rate Increase (Decrease), Amount 13,100,000us-gaap_PublicUtilitiesRequestedRateIncreaseDecreaseAmount
/ us-gaap_PublicUtilitiesRegulatoryProceedingAxis
= pny_TennesseeIMRPetitionAugust2013Member
/ us-gaap_RegulatoryAgencyAxis
= pny_TennesseeRegulatoryAuthorityMember		                                      
Tennessee Regulatory Authority [Member] | Tennessee IMR Settlement 2013 [Member]                                        
Public Utilities, Rate Matters, Approved [Abstract]                                        
Public Utilities, Approved Rate Increase (Decrease), Amount 13,100,000us-gaap_PublicUtilitiesApprovedRateIncreaseDecreaseAmount
/ us-gaap_PublicUtilitiesRegulatoryProceedingAxis
= pny_TennesseeIMRSettlement2013Member
/ us-gaap_RegulatoryAgencyAxis
= pny_TennesseeRegulatoryAuthorityMember		                                      
Tennessee Regulatory Authority [Member] | TRA IMR Rate Adjustment Petition Filed December 2014 [Member] | Subsequent Event [Member]                                        
Public Utilities, Rate Matters, Requested [Abstract]                                        
Public Utilities, Requested Rate Increase (Decrease), Amount                   6,500,000us-gaap_PublicUtilitiesRequestedRateIncreaseDecreaseAmount
/ us-gaap_PublicUtilitiesRegulatoryProceedingAxis
= pny_TRAPetitionFiledIMRDecember2014Member
/ us-gaap_RegulatoryAgencyAxis
= pny_TennesseeRegulatoryAuthorityMember
/ us-gaap_SubsequentEventTypeAxis
= us-gaap_SubsequentEventMember		                    
Public Utilities, Disclosure of Rate Matters                   In December 2014, we filed a petition with the TRA seeking authority to collect an additional $6.5 million in annual IMR margin revenues effective January 2015 based on $54 million of capital investments in integrity and safety projects over the twelve-month period ending October 31, 2014. We are waiting on a ruling from the TRA at this time.                    
Tennessee Regulatory Authority [Member] | TRA Petition to Amortize and Refund Customers for Excess Deferred Taxes [Member]                                        
Public Utilities, Rate Matters, Requested [Abstract]                                        
Public Utilities, Requested Rate Increase (Decrease), Amount (4,700,000)us-gaap_PublicUtilitiesRequestedRateIncreaseDecreaseAmount
/ us-gaap_PublicUtilitiesRegulatoryProceedingAxis
= pny_TRAPetitiontoAmortizeandRefundCustomersforExcessDeferredTaxesMember
/ us-gaap_RegulatoryAgencyAxis
= pny_TennesseeRegulatoryAuthorityMember		                                      
Tennessee Regulatory Authority [Member] | Tennessee CNG Rider Petition September 2014 [Member] | Subsequent Event [Member]                                        
Public Utilities, Rate Matters, Requested [Abstract]                                        
Public Utilities, Disclosure of Rate Matters                 In September 2014, we filed a petition with the TRA seeking authority to implement a compressed natural gas infrastructure rider to recover the costs of our capital investments in infrastructure and equipment associated with this alternative motor vehicle transportation fuel. We proposed that the tariff rider be effective October 1, 2014 with an initial rate adjustment on November 1, 2014 based on capital expenditures incurred through June 2014 and for rates to be updated annually outside of general rate cases for the return of and on these capital investments. In November 2014, the TRA consolidated this docket with a separate petition we filed seeking modifications to our tariff regarding service to customers using natural gas as a motor fuel. The TRA suspended the proposed tariffs through February 9, 2015. A hearing on this matter has been scheduled for January 12, 2015.                      
Tennessee Regulatory Authority [Member] | Environmental costs | General Rate Application Settlement 2012 [Member]                                        
Public Utilities, Rate Matters, Approved [Abstract]                                        
Amortization Time Period For Specified Expenses 8 years                                      
Public Utilities, Rate Matters, Requested [Abstract]                                        
Regulatory Assets                                     2,000,000us-gaap_RegulatoryAssets
/ us-gaap_PublicUtilitiesRegulatoryProceedingAxis
= pny_GeneralRateApplicationSettlement2012Member
/ us-gaap_RegulatoryAgencyAxis
= pny_TennesseeRegulatoryAuthorityMember
/ us-gaap_RegulatoryAssetAxis
= us-gaap_EnvironmentalRestorationCostsMember		  
Tennessee Regulatory Authority [Member] | Other Regulatory Assets (Liabilities) [Member] | General Rate Application Settlement 2012 [Member]                                        
Public Utilities, Rate Matters, Approved [Abstract]                                        
Amortization Time Period For Specified Expenses 8 years                                      
Regulatory Noncurrent Asset, End Date for Recovery Feb. 28, 2020                                      
Public Utilities, Rate Matters, Requested [Abstract]                                        
Regulatory Assets                                     1,000,000us-gaap_RegulatoryAssets
/ us-gaap_PublicUtilitiesRegulatoryProceedingAxis
= pny_GeneralRateApplicationSettlement2012Member
/ us-gaap_RegulatoryAgencyAxis
= pny_TennesseeRegulatoryAuthorityMember
/ us-gaap_RegulatoryAssetAxis
= us-gaap_OtherRegulatoryAssetsLiabilitiesMember