Investment Nonconsolidated Entity	6 Months Ended
Jun. 30, 2017
Equity Method Investments and Joint Ventures [Abstract]
Equity in Nonconsolidated Investments	Investment in Nonconsolidated Entity As of June 30, 2017, EQM owned a 45.5% interest (the MVP Interest) in Mountain Valley Pipeline, LLC (MVP Joint Venture). The MVP Joint Venture plans to construct the Mountain Valley Pipeline (MVP), an estimated 300-mile natural gas interstate pipeline spanning from northern West Virginia to southern Virginia. The MVP Joint Venture has secured a total of 2.0 Bcf per day of 20-year firm capacity commitments, including a 1.29 Bcf per day firm capacity commitment by the Company. On June 23, 2017, the Federal Energy Regulatory Commission (FERC) issued the Final Environmental Impact Statement for the project, and the MVP Joint Venture anticipates receiving the FERC certificate by the fourth quarter of 2017. The pipeline is targeted to be placed in-service during the fourth quarter of 2018. The MVP Joint Venture has been determined to be a variable interest entity because it has insufficient equity to finance its activities during the construction stage of the project. EQM is not the primary beneficiary because it does not have the power to direct the activities of the MVP Joint Venture that most significantly impact its economic performance. Certain business decisions require the approval of owners holding more than a 66 2/3% interest in the MVP Joint Venture and no one member owns more than a 66 2/3% interest. The Company, through its ownership interest in EQM, accounts for the interest in the MVP Joint Venture as an equity method investment as EQM has the ability to exercise significant influence over operating and financial policies of the MVP Joint Venture. In May 2017, the MVP Joint Venture issued a capital call notice to MVP Holdco, LLC (MVP Holdco), a direct wholly owned subsidiary of EQM, for $18.3 million, of which $5.5 million was paid on July 13, 2017 and the remaining $12.8 million is expected to be paid on August 15, 2017. The capital contribution payable has been reflected on the Condensed Consolidated Balance Sheet as of June 30, 2017 with a corresponding increase to the Company's investment in the MVP Joint Venture. The Company’s ownership share of the earnings for the three months ended June 30, 2017 and 2016 related to the MVP Joint Venture was $5.1 million and $1.9 million, respectively. The Company’s ownership share of the earnings for the six months ended June 30, 2017 and 2016 related to the MVP Joint Venture was $9.4 million and $3.4 million, respectively. These earnings are reported in other income on the Statements of Consolidated Operations for the periods presented. As of June 30, 2017, EQM had issued a $91 million performance guarantee in favor of the MVP Joint Venture to provide performance assurances for MVP Holdco's obligations to fund its proportionate share of the construction budget for the MVP. Upon the FERC's initial release to begin construction of the MVP, EQM's guarantee will terminate; EQM will then be obligated to issue a new guarantee in an amount equal to 33% of MVP Holdco’s remaining obligations to make capital contributions to the MVP Joint Venture in connection with the then remaining construction budget, less, subject to certain limits, any credit assurances issued by any affiliate of EQM under such affiliate's precedent agreement with the MVP Joint Venture. As of June 30, 2017, EQM's maximum financial statement exposure related to the MVP Joint Venture was approximately $352 million, which included the investment in nonconsolidated entity balance on the Condensed Consolidated Balance Sheet as of June 30, 2017 and amounts which could have become due under the performance guarantee as of that date.

Investment in Nonconsolidated Entity

As of June 30, 2017, EQM owned a 45.5% interest (the MVP Interest) in Mountain Valley Pipeline, LLC (MVP Joint Venture). The MVP Joint Venture plans to construct the Mountain Valley Pipeline (MVP), an estimated 300-mile natural gas interstate pipeline spanning from northern West Virginia to southern Virginia. The MVP Joint Venture has secured a total of 2.0 Bcf per day of 20-year firm capacity commitments, including a 1.29 Bcf per day firm capacity commitment by the Company. On June 23, 2017, the Federal Energy Regulatory Commission (FERC) issued the Final Environmental Impact Statement for the project, and the MVP Joint Venture anticipates receiving the FERC certificate by the fourth quarter of 2017. The pipeline is targeted to be placed in-service during the fourth quarter of 2018.

The MVP Joint Venture has been determined to be a variable interest entity because it has insufficient equity to finance its activities during the construction stage of the project. EQM is not the primary beneficiary because it does not have the power to direct the activities of the MVP Joint Venture that most significantly impact its economic performance. Certain business decisions require the approval of owners holding more than a 66 2/3% interest in the MVP Joint Venture and no one member owns more than a 66 2/3% interest. The Company, through its ownership interest in EQM, accounts for the interest in the MVP Joint Venture as an equity method investment as EQM has the ability to exercise significant influence over operating and financial policies of the MVP Joint Venture.

In May 2017, the MVP Joint Venture issued a capital call notice to MVP Holdco, LLC (MVP Holdco), a direct wholly owned subsidiary of EQM, for $18.3 million, of which $5.5 million was paid on July 13, 2017 and the remaining $12.8 million is expected to be paid on August 15, 2017. The capital contribution payable has been reflected on the Condensed Consolidated Balance Sheet as of June 30, 2017 with a corresponding increase to the Company's investment in the MVP Joint Venture.

The Company’s ownership share of the earnings for the three months ended June 30, 2017 and 2016 related to the MVP Joint Venture was $5.1 million and $1.9 million, respectively. The Company’s ownership share of the earnings for the six months ended June 30, 2017 and 2016 related to the MVP Joint Venture was $9.4 million and $3.4 million, respectively. These earnings are reported in other income on the Statements of Consolidated Operations for the periods presented.

As of June 30, 2017, EQM had issued a $91 million performance guarantee in favor of the MVP Joint Venture to provide performance assurances for MVP Holdco's obligations to fund its proportionate share of the construction budget for the MVP. Upon the FERC's initial release to begin construction of the MVP, EQM's guarantee will terminate; EQM will then be obligated to issue a new guarantee in an amount equal to 33% of MVP Holdco’s remaining obligations to make capital contributions to the MVP Joint Venture in connection with the then remaining construction budget, less, subject to certain limits, any credit assurances issued by any affiliate of EQM under such affiliate's precedent agreement with the MVP Joint Venture.

As of June 30, 2017, EQM's maximum financial statement exposure related to the MVP Joint Venture was approximately $352 million, which included the investment in nonconsolidated entity balance on the Condensed Consolidated Balance Sheet as of June 30, 2017 and amounts which could have become due under the performance guarantee as of that date.