2.4.0.8 Html 214 241 1 true 35 0 false 5 false false R1.htm 0001000 - Document - Document And Entity Information Sheet http://www.questar.com/role/DocumentAndEntityInformation Document And Entity Information false false R2.htm 1001000 - Statement - CONSOLIDATED STATEMENTS OF INCOME Sheet http://www.questar.com/role/ConsolidatedStatementsOfIncome CONSOLIDATED STATEMENTS OF INCOME false false R3.htm 1002000 - Statement - CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME Sheet http://www.questar.com/role/CondensedConsolidatedStatementsOfComprehensiveIncome CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME true false R4.htm 1004000 - Statement - CONDENSED CONSOLIDATED BALANCE SHEETS Sheet http://www.questar.com/role/CondensedConsolidatedBalanceSheets CONDENSED CONSOLIDATED BALANCE SHEETS false false R5.htm 1005000 - Statement - CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS Sheet http://www.questar.com/role/CondensedConsolidatedStatementsOfCashFlows CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS false false R6.htm 2101100 - Disclosure - Nature of Business (Notes) Notes http://www.questar.com/role/NatureOfBusinessNotes Nature of Business (Notes) false false R7.htm 2102100 - Disclosure - Basis of Presentation of Interim Financial Statements (Notes) Notes http://www.questar.com/role/BasisOfPresentationOfInterimFinancialStatementsNotes Basis of Presentation of Interim Financial Statements (Notes) false false R8.htm 2103100 - Disclosure - Earnings Per Share (Notes) Notes http://www.questar.com/role/EarningsPerShareNotes Earnings Per Share (Notes) false false R9.htm 2104100 - Disclosure - Other Comprehensive Income (Notes) Notes http://www.questar.com/role/OtherComprehensiveIncomeNotes Other Comprehensive Income (Notes) false false R10.htm 2105100 - Disclosure - Asset Retirement Obligations (Notes) Notes http://www.questar.com/role/AssetRetirementObligationsNotes Asset Retirement Obligations (Notes) false false R11.htm 2106100 - Disclosure - Fair Value Measurements (Notes) Notes http://www.questar.com/role/FairValueMeasurementsNotes Fair Value Measurements (Notes) false false R12.htm 2107100 - Disclosure - Derivatives and Hedging (Notes) Notes http://www.questar.com/role/DerivativesAndHedgingNotes Derivatives and Hedging (Notes) false false R13.htm 2108100 - Disclosure - Share-Based Compensation (Notes) Notes http://www.questar.com/role/ShareBasedCompensationNotes Share-Based Compensation (Notes) false false R14.htm 2109100 - Disclosure - Operations by Line of Business (Notes) Notes http://www.questar.com/role/OperationsByLineOfBusinessNotes Operations by Line of Business (Notes) false false R15.htm 2110100 - Disclosure - Employee Benefits (Notes) Notes http://www.questar.com/role/EmployeeBenefitsNotes Employee Benefits (Notes) false false R16.htm 2111100 - Disclosure - Contingencies (Notes) Notes http://www.questar.com/role/ContingenciesNotes Contingencies (Notes) false false R17.htm 2112100 - Disclosure - Asset Impairments (Notes) Notes http://www.questar.com/role/AssetImpairmentsNotes Asset Impairments (Notes) false false R18.htm 2113100 - Disclosure - Wexpro Acquisition of Producing Properties and Inclusion in Wexpro II Agreement (Notes) Notes http://www.questar.com/role/WexproAcquisitionOfProducingPropertiesAndInclusionInWexproIiAgreementNotes Wexpro Acquisition of Producing Properties and Inclusion in Wexpro II Agreement (Notes) false false R19.htm 2114100 - Disclosure - Recent Accounting Developments (Notes) Notes http://www.questar.com/role/RecentAccountingDevelopmentsNotes Recent Accounting Developments (Notes) false false R20.htm 2202201 - Disclosure - Basis of Presentation of Interim Financial Statements (Policies) Sheet http://www.questar.com/role/BasisOfPresentationOfInterimFinancialStatementsPolicies Basis of Presentation of Interim Financial Statements (Policies) false false R21.htm 2302302 - Disclosure - Basis of Presentation of Interim Financial Statements (Tables) Sheet http://www.questar.com/role/BasisOfPresentationOfInterimFinancialStatementsTables Basis of Presentation of Interim Financial Statements (Tables) false false R22.htm 2303301 - Disclosure - Earnings Per Share (Tables) Sheet http://www.questar.com/role/EarningsPerShareTables Earnings Per Share (Tables) false false R23.htm 2304301 - Disclosure - Other Comprehensive Income (Tables) Sheet http://www.questar.com/role/OtherComprehensiveIncomeTables Other Comprehensive Income (Tables) false false R24.htm 2305301 - Disclosure - Asset Retirement Obligations (Tables) Sheet http://www.questar.com/role/AssetRetirementObligationsTables Asset Retirement Obligations (Tables) false false R25.htm 2306301 - Disclosure - Fair Value Measurements (Tables) Sheet http://www.questar.com/role/FairValueMeasurementsTables Fair Value Measurements (Tables) false false R26.htm 2308301 - Disclosure - Share-Based Compensation (Tables) Sheet http://www.questar.com/role/ShareBasedCompensationTables Share-Based Compensation (Tables) false false R27.htm 2309301 - Disclosure - Operations by Line of Business (Tables) Sheet http://www.questar.com/role/OperationsByLineOfBusinessTables Operations by Line of Business (Tables) false false R28.htm 2310301 - Disclosure - Employee Benefits (Tables) Sheet http://www.questar.com/role/EmployeeBenefitsTables Employee Benefits (Tables) false false R29.htm 2401401 - Disclosure - Nature of Business (Details) Sheet http://www.questar.com/role/NatureOfBusinessDetails Nature of Business (Details) false false R30.htm 2402403 - Disclosure - Basis of Presentation of Interim Financial Statements (Details) Sheet http://www.questar.com/role/BasisOfPresentationOfInterimFinancialStatementsDetails Basis of Presentation of Interim Financial Statements (Details) false false R31.htm 2403402 - Disclosure - Earnings Per Share (Details) Sheet http://www.questar.com/role/EarningsPerShareDetails Earnings Per Share (Details) false false R32.htm 2404402 - Disclosure - Other Comprehensive Income (Details) Sheet http://www.questar.com/role/OtherComprehensiveIncomeDetails Other Comprehensive Income (Details) false false R33.htm 2405402 - Disclosure - Asset Retirement Obligations (Details) Sheet http://www.questar.com/role/AssetRetirementObligationsDetails Asset Retirement Obligations (Details) false false R34.htm 2406402 - Disclosure - Fair Value Measurements (Details) Sheet http://www.questar.com/role/FairValueMeasurementsDetails Fair Value Measurements (Details) false false R35.htm 2407401 - Disclosure - Derivatives and Hedging (Details) Sheet http://www.questar.com/role/DerivativesAndHedgingDetails Derivatives and Hedging (Details) false false R36.htm 2408402 - Disclosure - Share-Based Compensation General (Details) Sheet http://www.questar.com/role/ShareBasedCompensationGeneralDetails Share-Based Compensation General (Details) false false R37.htm 2408403 - Disclosure - Share-Based Compensation Stock options (Details) Sheet http://www.questar.com/role/ShareBasedCompensationStockOptionsDetails Share-Based Compensation Stock options (Details) false false R38.htm 2408404 - Disclosure - Share-Based Compensation Restricted shares (Details) Sheet http://www.questar.com/role/ShareBasedCompensationRestrictedSharesDetails Share-Based Compensation Restricted shares (Details) false false R39.htm 2408405 - Disclosure - Share-Based Compensation Restricted stock units (Details) Sheet http://www.questar.com/role/ShareBasedCompensationRestrictedStockUnitsDetails Share-Based Compensation Restricted stock units (Details) false false R40.htm 2408406 - Disclosure - Share-Based Compensation Performance shares (Details) Sheet http://www.questar.com/role/ShareBasedCompensationPerformanceSharesDetails Share-Based Compensation Performance shares (Details) false false R41.htm 2409402 - Disclosure - Operations by Line of Business (Details) Sheet http://www.questar.com/role/OperationsByLineOfBusinessDetails Operations by Line of Business (Details) false false R42.htm 2410402 - Disclosure - Employee Benefits (Details) Sheet http://www.questar.com/role/EmployeeBenefitsDetails Employee Benefits (Details) false false R43.htm 2412401 - Disclosure - Asset Impairments (Details) Sheet http://www.questar.com/role/AssetImpairmentsDetails Asset Impairments (Details) false false R44.htm 2413401 - Disclosure - Wexpro Acquisition of Producing Properties and Inclusion in Wexpro II Agreement (Details) Sheet http://www.questar.com/role/WexproAcquisitionOfProducingPropertiesAndInclusionInWexproIiAgreementDetails Wexpro Acquisition of Producing Properties and Inclusion in Wexpro II Agreement (Details) false false All Reports Book All Reports 'Monetary' elements on report '2406402 - Disclosure - Fair Value Measurements (Details)' had a mix of different decimal attribute values. Process Flow-Through: 1001000 - Statement - CONSOLIDATED STATEMENTS OF INCOME Process Flow-Through: 1002000 - Statement - CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME Process Flow-Through: 1004000 - Statement - CONDENSED CONSOLIDATED BALANCE SHEETS Process Flow-Through: Removing column 'Jun. 30, 2014' Process Flow-Through: Removing column 'Jun. 30, 2013' Process Flow-Through: Removing column 'Dec. 31, 2012' Process Flow-Through: 1005000 - Statement - CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS Process Flow-Through: Removing column '12 Months Ended Sep. 30, 2014' Process Flow-Through: Removing column '12 Months Ended Sep. 30, 2013' str-20140930.xml str-20140930.xsd str-20140930_cal.xml str-20140930_def.xml str-20140930_lab.xml str-20140930_pre.xml true true