2.4.0.82403407 - Disclosure - Accounting for Derivative Instruments and Hedging Activities Contractual Contingent Liability (Details)truefalseIn Thousands, unless otherwise specifiedfalse1false USDfalsefalse$I2013Q2_us-gaap_DerivativeInstrumentRiskAxis_psd_ElectricPortfolioMemberhttp://www.sec.gov/CIK0001085392instant2013-06-30T00:00:000001-01-01T00:00:00usdStandardhttp://www.xbrl.org/2003/iso4217USDiso42170USDUSD$1true 3us-gaap_DerivativeLineItemsus-gaap_truenadurationfalsefalsefalsefalsefalsefalsefalsefalseterseLabel1falsefalsefalse00falsefalsefalsexbrli:stringItemTypestringfalse0Derivative [Line Items]2false 4us-gaap_DerivativeNetLiabilityPositionAggregateFairValueus-gaap_truecreditinstantfalsefalsefalsefalsefalsefalsefalsetruenegatedTerseLabel1truefalsefalse-53619000-53619[1]USD$falsetruefalsexbrli:monetaryItemTypemonetaryThe aggregate fair value amounts of derivative instruments that contain credit-risk-related contingent features that are in a net liability position at the end of the reporting period. 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Excludes NPNS, accounts payable and accounts receivable.2Failure by PSE to maintain an investment grade credit rating from each of the major credit rating agencies provides counterparties a contractual right to demand collateral.3Collateral requirements may vary, based on changes in the forward value of underlying transactions relative to contractually defined collateral thresholds.falseAccounting for Derivative Instruments and Hedging Activities Contractual Contingent Liability (Details) (Electric portfolio [Member], USD $)ThousandsUnKnownUnKnownUnKnowntruefalsefalseSheethttp://www.pugetenergy.com/role/AccountingForDerivativeInstrumentsAndHedgingActivitiesContractualContingentLiabilityDetails125