2.4.0.82403402 - Disclosure - Accounting for Derivative Instruments and Hedging Activities Derivative Activity and Notional Amounts (Details)truefalseIn Millions, unless otherwise specifiedfalse1false USDfalsefalse$I2013Q2_us-gaap_DerivativeInstrumentRiskAxis_us-gaap_InterestRateSwapMember_us-gaap_HedgingDesignationAxis_us-gaap_NondesignatedMemberhttp://www.sec.gov/CIK0001085392instant2013-06-30T00:00:000001-01-01T00:00:00usdStandardhttp://www.xbrl.org/2003/iso4217USDiso42170USDUSD$2false USDfalsefalse$I2012Q4_us-gaap_DerivativeInstrumentRiskAxis_us-gaap_InterestRateSwapMember_us-gaap_HedgingDesignationAxis_us-gaap_NondesignatedMemberhttp://www.sec.gov/CIK0001085392instant2012-12-31T00:00:000001-01-01T00:00:00usdStandardhttp://www.xbrl.org/2003/iso4217USDiso42170USDUSD$1false 0truefalsetruefalsefalsefalsefalsefalsefalse1falsefalsefalse00falsefalsefalse2falsefalsefalse00falsefalsefalse1false USDtruefalse$I2013Q2_us-gaap_DerivativeInstrumentRiskAxis_us-gaap_InterestRateSwapMember_us-gaap_HedgingDesignationAxis_us-gaap_NondesignatedMemberhttp://www.sec.gov/CIK0001085392instant2013-06-30T00:00:000001-01-01T00:00:00falsefalseInterest Rate Swap [Member]us-gaap_DerivativeInstrumentRiskAxisxbrldihttp://xbrl.org/2006/xbrldius-gaap_InterestRateSwapMemberus-gaap_DerivativeInstrumentRiskAxisexplicitMemberfalsefalseNot Designated as Hedging Instrument [Member]us-gaap_HedgingDesignationAxisxbrldihttp://xbrl.org/2006/xbrldius-gaap_NondesignatedMemberus-gaap_HedgingDesignationAxisexplicitMemberusdStandardhttp://www.xbrl.org/2003/iso4217USDiso42170USDUSD$nanafalse0Interest Rate Swap [Member] | Not Designated as Hedging Instrument [Member]2true 3us-gaap_DerivativeLineItemsus-gaap_truenadurationfalsefalsefalsefalsefalsefalsefalsefalseterseLabel1falsefalsefalse00falsefalsefalse2falsefalsefalse00falsefalsefalsexbrli:stringItemTypestringfalse0Derivative [Line Items]3false 4invest_DerivativeNotionalAmountinvest_falsenainstantfalsefalsefalsefalsefalsefalsefalsefalseterseLabel1truefalsefalse450000000450[1]USD$falsetruefalse2truefalsefalse450000000450[1]USD$falsetruefalsexbrli:monetaryItemTypemonetaryAggregate notional amount specified by the derivative(s). Expressed as an absolute value.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Article 12 -Section 13 -Sentence Column B false2Derivative, Notional Amount4false 0truefalsetruefalsefalsefalsefalsefalsefalse1falsefalsefalse00falsefalsefalse2falsefalsefalse00falsefalsefalse3false truefalseI2013Q2_us-gaap_DerivativeInstrumentRiskAxis_psd_NaturalGasDerivativesMember_us-gaap_HedgingDesignationAxis_us-gaap_NondesignatedMemberhttp://www.sec.gov/CIK0001085392instant2013-06-30T00:00:000001-01-01T00:00:00falsefalseNatural Gas Derivatives [Member]us-gaap_DerivativeInstrumentRiskAxisxbrldihttp://xbrl.org/2006/xbrldipsd_NaturalGasDerivativesMemberus-gaap_DerivativeInstrumentRiskAxisexplicitMemberfalsefalseNot Designated as Hedging Instrument [Member]us-gaap_HedgingDesignationAxisxbrldihttp://xbrl.org/2006/xbrldius-gaap_NondesignatedMemberus-gaap_HedgingDesignationAxisexplicitMembermmbtuStandardhttp://www.xbrl.org/2009/utrMMBTUutreg0nanafalse0Natural Gas Derivatives [Member] | Not Designated as Hedging Instrument [Member]5true 3us-gaap_DerivativeLineItemsus-gaap_truenadurationfalsefalsefalsefalsefalsefalsefalsefalseterseLabel1falsefalsefalse00falsefalsefalse2falsefalsefalse00falsefalsefalsexbrli:stringItemTypestringfalse0Derivative [Line Items]6false 4invest_DerivativeNonmonetaryNotionalAmountinvest_falsenainstantfalsefalsefalsefalsefalsefalsefalsefalseverboseLabel1truefalsefalse459420774459420774[2]falsefalsefalse2truefalsefalse516909006516909006[2]falsefalsefalsexbrli:decimalItemTypedecimalAggregate notional amount of derivative expressed in nonmonetary units. For example, the number of barrels specified in a fuel oil forward purchase contract.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Article 12 -Section 13 -Sentence Column B false256Derivative, Notional amount, Nonmonetary7false 0truefalsetruefalsefalsefalsefalsefalsefalse1falsefalsefalse00falsefalsefalse2falsefalsefalse00falsefalsefalse5false truefalseI2013Q2_us-gaap_DerivativeInstrumentRiskAxis_psd_ElectricGenerationFuelMember_us-gaap_HedgingDesignationAxis_us-gaap_NondesignatedMemberhttp://www.sec.gov/CIK0001085392instant2013-06-30T00:00:000001-01-01T00:00:00falsefalseElectric generation fuel [Member]us-gaap_DerivativeInstrumentRiskAxisxbrldihttp://xbrl.org/2006/xbrldipsd_ElectricGenerationFuelMemberus-gaap_DerivativeInstrumentRiskAxisexplicitMemberfalsefalseNot Designated as Hedging Instrument [Member]us-gaap_HedgingDesignationAxisxbrldihttp://xbrl.org/2006/xbrldius-gaap_NondesignatedMemberus-gaap_HedgingDesignationAxisexplicitMembermmbtuStandardhttp://www.xbrl.org/2009/utrMMBTUutreg0nanafalse0Electric generation fuel [Member] | Not Designated as Hedging Instrument [Member]8true 3us-gaap_DerivativeLineItemsus-gaap_truenadurationfalsefalsefalsefalsefalsefalsefalsefalseterseLabel1falsefalsefalse00falsefalsefalse2falsefalsefalse00falsefalsefalsexbrli:stringItemTypestringfalse0Derivative [Line Items]9false 4invest_DerivativeNonmonetaryNotionalAmountinvest_falsenainstantfalsefalsefalsefalsefalsefalsefalsefalseverboseLabel1truefalsefalse143999235143999235falsefalsefalse2truefalsefalse129693200129693200falsefalsefalsexbrli:decimalItemTypedecimalAggregate notional amount of derivative expressed in nonmonetary units. For example, the number of barrels specified in a fuel oil forward purchase contract.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Article 12 -Section 13 -Sentence Column B false256Derivative, Notional amount, Nonmonetary10false 0truefalsetruefalsefalsefalsefalsefalsefalse1falsefalsefalse00falsefalsefalse2falsefalsefalse00falsefalsefalse7false truefalseI2013Q2_us-gaap_DerivativeInstrumentRiskAxis_psd_PurchasedElectricityMember_us-gaap_HedgingDesignationAxis_us-gaap_NondesignatedMemberhttp://www.sec.gov/CIK0001085392instant2013-06-30T00:00:000001-01-01T00:00:00falsefalsePurchased electricity [Member]us-gaap_DerivativeInstrumentRiskAxisxbrldihttp://xbrl.org/2006/xbrldipsd_PurchasedElectricityMemberus-gaap_DerivativeInstrumentRiskAxisexplicitMemberfalsefalseNot Designated as Hedging Instrument [Member]us-gaap_HedgingDesignationAxisxbrldihttp://xbrl.org/2006/xbrldius-gaap_NondesignatedMemberus-gaap_HedgingDesignationAxisexplicitMembermwhStandardhttp://www.xbrl.org/2009/utrMWhutreg0nanafalse0Purchased electricity [Member] | Not Designated as Hedging Instrument [Member]11true 3us-gaap_DerivativeLineItemsus-gaap_truenadurationfalsefalsefalsefalsefalsefalsefalsefalseterseLabel1falsefalsefalse00falsefalsefalse2falsefalsefalse00falsefalsefalsexbrli:stringItemTypestringfalse0Derivative [Line Items]12false 4invest_DerivativeNonmonetaryNotionalAmountinvest_falsenainstantfalsefalsefalsefalsefalsefalsefalsefalseverboseLabel1truefalsefalse77978257797825falsefalsefalse2truefalsefalse1072241510722415falsefalsefalsexbrli:decimalItemTypedecimalAggregate notional amount of derivative expressed in nonmonetary units. For example, the number of barrels specified in a fuel oil forward purchase contract.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Article 12 -Section 13 -Sentence Column B false256Derivative, Notional amount, Nonmonetary13false 0truefalsetruefalsefalsefalsefalsefalsefalse1falsefalsefalse00falsefalsefalse2falsefalsefalse00falsefalsefalse9false truefalseI2013Q2_dei_LegalEntityAxis_us-gaap_ParentCompanyMember_us-gaap_DerivativeInstrumentRiskAxis_us-gaap_InterestRateSwapMemberhttp://www.sec.gov/CIK0001085392instant2013-06-30T00:00:000001-01-01T00:00:00falsefalsePUGET ENERGY [Member]dei_LegalEntityAxisxbrldihttp://xbrl.org/2006/xbrldius-gaap_ParentCompanyMemberdei_LegalEntityAxisexplicitMemberfalsefalseInterest Rate Swap [Member]us-gaap_DerivativeInstrumentRiskAxisxbrldihttp://xbrl.org/2006/xbrldius-gaap_InterestRateSwapMemberus-gaap_DerivativeInstrumentRiskAxisexplicitMemberContractsStandardhttp://www.pugetenergy.com/20130630Contractspsd0nanafalse0PUGET ENERGY [Member] | Interest Rate Swap [Member]14true 3us-gaap_DerivativeLineItemsus-gaap_truenadurationfalsefalsefalsefalsefalsefalsefalsefalseterseLabel1falsefalsefalse00falsefalsefalse2falsefalsefalse00falsefalsefalsexbrli:stringItemTypestringfalse0Derivative [Line Items]15false 4us-gaap_NumberOfInterestRateDerivativesHeldus-gaap_truenainstantfalsefalsefalsefalsefalsefalsefalsefalseterseLabel1truefalsefalse22falsefalsefalse2falsefalsefalse00falsefalsefalsexbrli:integerItemTypeintegerNumber of interest rate derivative instruments held by the entity at the reporting date.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 50 -Paragraph 1A -Subparagraph (d) -URI http://asc.fasb.org/extlink&oid=7476318&loc=SL5579245-113959 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 50 -Paragraph 1B -URI http://asc.fasb.org/extlink&oid=7476318&loc=SL5580258-113959 false256Number of Interest Rate Derivatives Held1Interest rate swap contracts are only held at Puget Energy.2PSE had a net derivative liability and an offsetting regulatory asset of $70.4 million at June 30, 2013 and $96.0 million at December 31, 2012 related to contracts used to economically hedge the cost of physical gas purchased to serve natural gas customers. All fair value adjustments on derivatives relating to the natural gas business have been reclassified to a deferred account in accordance with ASC 980, “Regulated Operations” (ASC 980) due to the Purchased Gas Adjustment (PGA) mechanism.falseAccounting for Derivative Instruments and Hedging Activities Derivative Activity and Notional Amounts (Details) (USD $)MillionsUnKnownUnKnownUnKnowntruefalsefalseSheethttp://www.pugetenergy.com/role/AccountingForDerivativeInstrumentsAndHedgingActivitiesDerivativeActivityAndNotionalAmountsDetails215