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Nature of Business	9 Months Ended
Nature of Business	Sep. 30, 2016
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Nature of Business	Nature of Business Questar Gas is a wholly-owned subsidiary of Dominion Questar which, effective September 2016, is a wholly-owned subsidiary of Dominion. The Company provides retail natural gas distribution in Utah, southwestern Wyoming and a small portion of southeastern Idaho. Questar Gas is regulated by the PSCU and the PSCW. The Public Utility Commission of Idaho has contracted with the PSCU for rate oversight of Questar Gas' Idaho operations.