Contingencies	6 Months Ended
Jun. 30, 2016
Commitments and Contingencies Disclosure [Abstract]
Contingencies	Contingencies Questar and each of its subsidiaries are involved in various commercial, environmental, and regulatory claims. Litigation and other legal proceedings arise in the ordinary course of business. Management does not believe any such litigation or other legal proceedings arising in the ordinary course of business individually or in the aggregate, will have a material adverse effect on Questar's, Questar Gas's or Questar Pipeline's financial position, results of operations or cash flows. A liability is recorded for a loss contingency when its occurrence is probable and its amount can be reasonably estimated. If some amount within a range of possible outcomes appears to be a better estimate than any other amount within the range, that amount is recorded. Otherwise, the minimum amount in the range is recorded. Disclosures are provided for contingencies reasonably likely to occur, which would have a material adverse effect on Questar's, Questar Gas's or Questar Pipeline's financial position, results of operations or cash flows. Some of the claims involve highly complex issues relating to liability, damages and other matters subject to substantial uncertainties and, therefore, the probability of liability or an estimate of loss cannot be reasonably determined. Litigation The case related to operations entitled Questar Gas Company v. QEP Field Services Company that was filed in Third District Court in Salt Lake County, Utah on May 1, 2012, was settled on March 22, 2016. Questar Gas believes the settlement agreement reasonably resolves disputed issues regarding services and charges under the 1993 Gas Gathering Agreement. The settlement agreement did not result in a material impact on Questar's or Questar Gas's results of operation, financial position or cash flows. In February 2015, a trial was held in the case of Rocky Mountain Resources and Robert N. Floyd v. QEP Energy Company and Wexpro Company, Ninth Judicial District, County of Sublette, State of Wyoming, Case No. 2011-7816. Plaintiffs allege they are entitled to a 4% overriding royalty interest (ORRI) in a so-called replacement state oil and gas lease ultimately assigned to Wexpro and QEP Energy Company (QEP) in the Pinedale Field. Wexpro and QEP believe the former state leases subject to the ORRI expired and a new lease was issued by the State of Wyoming unburdened by the 4% ORRI. A jury decision was reached on February 13, 2015, that awarded the Plaintiffs $14.1 million from Wexpro and $16.2 million from QEP. Wexpro and QEP have filed an appeal of the case to the Wyoming Supreme Court and briefing began in May 2016 and will conclude in August 2016. Wexpro has accrued its estimate of liability in the case. Any additional royalties will be recovered from Questar Gas’s customers. Litigation Related to Proposed Merger As more fully described in Note 2, Questar entered into an Agreement and Plan of Merger with Dominion Resources, Inc. ("Dominion Resources") and its wholly-owned subsidiary, Diamond Beehive Corp. on January 31, 2016, pursuant to which Questar shareholders have the right to receive $25.00 per share in cash, subject to the satisfaction of specified conditions. If the Dominion Merger is completed, Questar will become a wholly-owned subsidiary of Dominion Resources. As of August 3, 2016, six lawsuits challenging the Merger have been filed purportedly on behalf of Questar shareholders, of which four are pending in the Third District Court, Salt Lake County, Utah, and two are pending in the United States District Court of Utah, Central Division. Each of the lawsuits names Questar, Questar’s directors, Dominion Resources and Diamond Beehive Corp. as defendants. The named plaintiffs in the four lawsuits pending in Third District Court are John Hansen, Eric Senatori, Shiva Stein and James E. Toth, and Teamsters Local 456 Pension Fund and Teamsters Local 456 Annuity Fund, respectively. The named plaintiffs in the two lawsuits pending in U.S. District Court are Kevin Hessel and Dan Ipson, respectively. All of the lawsuits are purported shareholder class actions advancing substantially the same allegations that the Merger Agreement was adopted in violation of the fiduciary duties of Questar’s directors and seeking injunctive relief to enjoin the Dominion Merger, as well as other remedies. All of the cases raise direct claims on behalf of Questar shareholders. In addition, one of the cases raises derivative claims on behalf of Questar. On April 21, 2016, the Third District Court granted a request to consolidate all four cases pending in Third District Court into Teamsters Local 456 Pension Fund, et. al. v. Ronald W. Jibson, et. al. (Case No. 160900938). On April 22, 2016, the court appointed Teamsters Local 456 Pension Fund as lead plaintiff in the consolidated matter. The court also appointed lead counsel and liaison counsel. On May 5, 2016 the parties of the state action entered into a Memorandum of Understanding and reached an agreement-in-principle providing for settlement of the state action, subject to confirmatory discovery and court approval. The federal plaintiffs are not signatories to the MOU and their cases remain pending, although the federal plaintiffs have stated that they intend to dismiss the federal cases within five days of the approval of the settlement and entry of an Order and Final Judgment in the state cases. The outcome of these lawsuits is uncertain, and additional lawsuits may be brought or additional claims advanced concerning the Merger. An adverse judgment for monetary damages could have an adverse effect on Questar’s operations.

Contingencies

Questar and each of its subsidiaries are involved in various commercial, environmental, and regulatory claims. Litigation and other legal proceedings arise in the ordinary course of business. Management does not believe any such litigation or other legal proceedings arising in the ordinary course of business individually or in the aggregate, will have a material adverse effect on Questar's, Questar Gas's or Questar Pipeline's financial position, results of operations or cash flows.

A liability is recorded for a loss contingency when its occurrence is probable and its amount can be reasonably estimated. If some amount within a range of possible outcomes appears to be a better estimate than any other amount within the range, that amount is recorded. Otherwise, the minimum amount in the range is recorded. Disclosures are provided for contingencies reasonably likely to occur, which would have a material adverse effect on Questar's, Questar Gas's or Questar Pipeline's financial position, results of operations or cash flows. Some of the claims involve highly complex issues relating to liability, damages and other matters subject to substantial uncertainties and, therefore, the probability of liability or an estimate of loss cannot be reasonably determined.

Litigation

The case related to operations entitled Questar Gas Company v. QEP Field Services Company that was filed in Third District Court in Salt Lake County, Utah on May 1, 2012, was settled on March 22, 2016. Questar Gas believes the settlement agreement reasonably resolves disputed issues regarding services and charges under the 1993 Gas Gathering Agreement. The settlement agreement did not result in a material impact on Questar's or Questar Gas's results of operation, financial position or cash flows.

In February 2015, a trial was held in the case of Rocky Mountain Resources and Robert N. Floyd v. QEP Energy Company and Wexpro Company, Ninth Judicial District, County of Sublette, State of Wyoming, Case No. 2011-7816. Plaintiffs allege they are entitled to a 4% overriding royalty interest (ORRI) in a so-called replacement state oil and gas lease ultimately assigned to Wexpro and QEP Energy Company (QEP) in the Pinedale Field. Wexpro and QEP believe the former state leases subject to the ORRI expired and a new lease was issued by the State of Wyoming unburdened by the 4% ORRI. A jury decision was reached on February 13, 2015, that awarded the Plaintiffs $14.1 million from Wexpro and $16.2 million from QEP. Wexpro and QEP have filed an appeal of the case to the Wyoming Supreme Court and briefing began in May 2016 and will conclude in August 2016. Wexpro has accrued its estimate of liability in the case. Any additional royalties will be recovered from Questar Gas’s customers.

Litigation Related to Proposed Merger

As more fully described in Note 2, Questar entered into an Agreement and Plan of Merger with Dominion Resources, Inc. ("Dominion Resources") and its wholly-owned subsidiary, Diamond Beehive Corp. on January 31, 2016, pursuant to which Questar shareholders have the right to receive $25.00 per share in cash, subject to the satisfaction of specified conditions. If the Dominion Merger is completed, Questar will become a wholly-owned subsidiary of Dominion Resources.

As of August 3, 2016, six lawsuits challenging the Merger have been filed purportedly on behalf of Questar shareholders, of which four are pending in the Third District Court, Salt Lake County, Utah, and two are pending in the United States District Court of Utah, Central Division. Each of the lawsuits names Questar, Questar’s directors, Dominion Resources and Diamond Beehive Corp. as defendants. The named plaintiffs in the four lawsuits pending in Third District Court are John Hansen, Eric Senatori, Shiva Stein and James E. Toth, and Teamsters Local 456 Pension Fund and Teamsters Local 456 Annuity Fund, respectively. The named plaintiffs in the two lawsuits pending in U.S. District Court are Kevin Hessel and Dan Ipson, respectively.

All of the lawsuits are purported shareholder class actions advancing substantially the same allegations that the Merger Agreement was adopted in violation of the fiduciary duties of Questar’s directors and seeking injunctive relief to enjoin the Dominion Merger, as well as other remedies. All of the cases raise direct claims on behalf of Questar shareholders. In addition, one of the cases raises derivative claims on behalf of Questar.

On April 21, 2016, the Third District Court granted a request to consolidate all four cases pending in Third District Court into Teamsters Local 456 Pension Fund, et. al. v. Ronald W. Jibson, et. al. (Case No. 160900938). On April 22, 2016, the court appointed Teamsters Local 456 Pension Fund as lead plaintiff in the consolidated matter. The court also appointed lead counsel and liaison counsel. On May 5, 2016 the parties of the state action entered into a Memorandum of Understanding and reached an agreement-in-principle providing for settlement of the state action, subject to confirmatory discovery and court approval. The federal plaintiffs are not signatories to the MOU and their cases remain pending, although the federal plaintiffs have stated that they intend to dismiss the federal cases within five days of the approval of the settlement and entry of an Order and Final Judgment in the state cases.

The outcome of these lawsuits is uncertain, and additional lawsuits may be brought or additional claims advanced concerning the Merger. An adverse judgment for monetary damages could have an adverse effect on Questar’s operations.