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This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy. false2Pre-tax net losses expected to be reclassified from AOCI to Consolidated statement of income12false 4str_ReclassificationFromAccumulatedOciToIncomeEstimatedTimeToTransferstr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalseterseLabel1falsefalsefalse00falsefalsefalse2falsefalsefalse00falsefalsefalse3falsefalsefalse0012 monthsfalsefalsefalse4falsefalsefalse00falsefalsefalse5falsefalsefalse00falsefalsefalse6falsefalsefalse00falsefalsefalse7falsefalsefalse00falsefalsefalse8falsefalsefalse00falsefalsefalse9falsefalsefalse00falsefalsefalse10falsefalsefalse00falsefalsefalse11falsefalsefalse00falsefalsefalse12falsefalsefalse00falsefalsefalse13falsefalsefalse00falsefalsefalse14falsefalsefalse00falsefalsefalse15falsefalsefalse00falsefalsefalseus-types:durationStringItemTypenormalizedstringThe time period estimated for the anticipated transfer of gains (losses), net from accumulated other comprehensive income into earnings.No definition available.false0Reclassification from accumulated OCI to income, estimated time to transferfalseDerivative Instruments and Hedging Activities Additional Information (Details) (USD $)NoRoundingUnKnownUnKnownUnKnowntruefalsefalseSheethttp://www.questar.com/role/DerivativeInstrumentsAndHedgingActivitiesAdditionalInformationDetails1512