RM Partners LP	9 Months Ended
Sep. 30, 2018
Equity Method Investments and Joint Ventures [Abstract]
RM Partners LP	RM Partners LP In connection with the Rice Merger, the Company acquired a 28.1% limited partner interest, all of the IDRs and the entire non-economic general partner interest in RMP. RMP's common units ceased to be publicly traded as a result of the Midstream Mergers. See the discussion of the RMP IDR Purchase and Midstream Mergers in Note B. Investment in Nonconsolidated Entity The Mountain Valley Pipeline, LLC (MVP Joint Venture) is constructing the Mountain Valley Pipeline (MVP), an estimated 300-mile natural gas interstate pipeline spanning from northern West Virginia to southern Virginia. EQM is the operator of the MVP and owned a 45.5% interest in the MVP Joint Venture as of September 30, 2018. The MVP Joint Venture is 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 MVP Joint Venture is an equity method investment for accounting purposes as EQM has the ability to exercise significant influence over operating and financial policies of the MVP Joint Venture. As currently designed, the MVP is estimated to cost a total of approximately $4.6 billion, excluding Allowance for Funds Used During Construction (AFUDC), with EQM funding approximately $2.2 billion through capital contributions made to the MVP Joint Venture, which includes approximately $65 million in excess of EQM's ownership interest. In 2018, EQM expects to provide capital contributions of $0.8 billion to $1.0 billion to the MVP Joint Venture. In September 2018, the MVP Joint Venture issued a capital call notice to MVP Holdco, LLC (MVP Holdco), a direct wholly owned subsidiary of EQM, for $456.0 million, of which $175.2 million was paid as of October 2018, and $280.8 million is expected to be paid in the fourth quarter of 2018. In addition, in September 2018, the MVP Joint Venture issued a capital call notice to MVP Holdco for $7.7 million for funding of the MVP Southgate project that is expected to be paid in the fourth quarter of 2018. The capital contribution payables have been reflected on the Condensed Consolidated Balance Sheet as of September 30, 2018 with corresponding increases to the Company's investment in the MVP Joint Venture. Equity income is EQM's portion of the MVP Joint Venture's AFUDC on construction of the MVP. As of September 30, 2018, EQM had issued a $91 million performance guarantee in favor of the MVP Joint Venture. The guarantee provides performance assurances of MVP Holdco's obligations to fund its proportionate share of the MVP construction budget. As of September 30, 2018, EQM's maximum financial statement exposure related to the MVP Joint Venture was approximately $1,391 million, which consists of the investment in nonconsolidated entity balance on the Condensed Consolidated Balance Sheet as of September 30, 2018 and amounts that could have become due under EQM's performance guarantee as of that date. Following the completion of the Separation, EQM expects the MVP Joint Venture guarantee will be approximately $345 million based on MVP Holdco's share of the estimated remaining MVP construction budget and terms of the agreement. In April 2018, the MVP Joint Venture announced the MVP Southgate project, a proposed 70-mile interstate pipeline that will extend from the MVP at Pittsylvania County, Virginia to new delivery points in Rockingham and Alamance Counties, North Carolina. This MVP Southgate project is anchored by a firm capacity commitment from PSNC Energy. The preliminary MVP Southgate project cost estimate is $350 million to $500 million, which is expected to be spent in 2019 and 2020. As of September 30, 2018, EQM had a 32.7% ownership interest in the MVP Southgate project and will operate the pipeline. Subject to approval by the FERC, the MVP Southgate project has a targeted in-service date of the fourth quarter 2020.

Investment in Nonconsolidated Entity

The Mountain Valley Pipeline, LLC (MVP Joint Venture) is constructing the Mountain Valley Pipeline (MVP), an estimated 300-mile natural gas interstate pipeline spanning from northern West Virginia to southern Virginia. EQM is the operator of the MVP and owned a 45.5% interest in the MVP Joint Venture as of September 30, 2018. The MVP Joint Venture is 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 MVP Joint Venture is an equity method investment for accounting purposes as EQM has the ability to exercise significant influence over operating and financial policies of the MVP Joint Venture. As currently designed, the MVP is estimated to cost a total of approximately $4.6 billion, excluding Allowance for Funds Used During Construction (AFUDC), with EQM funding approximately $2.2 billion through capital contributions made to the MVP Joint Venture, which includes approximately $65 million in excess of EQM's ownership interest. In 2018, EQM expects to provide capital contributions of $0.8 billion to $1.0 billion to the MVP Joint Venture.

In September 2018, the MVP Joint Venture issued a capital call notice to MVP Holdco, LLC (MVP Holdco), a direct wholly owned subsidiary of EQM, for $456.0 million, of which $175.2 million was paid as of October 2018, and $280.8 million is expected to be paid in the fourth quarter of 2018. In addition, in September 2018, the MVP Joint Venture issued a capital call notice to MVP Holdco for $7.7 million for funding of the MVP Southgate project that is expected to be paid in the fourth quarter of 2018. The capital contribution payables have been reflected on the Condensed Consolidated Balance Sheet as of September 30, 2018 with corresponding increases to the Company's investment in the MVP Joint Venture.

Equity income is EQM's portion of the MVP Joint Venture's AFUDC on construction of the MVP.

As of September 30, 2018, EQM had issued a $91 million performance guarantee in favor of the MVP Joint Venture. The guarantee provides performance assurances of MVP Holdco's obligations to fund its proportionate share of the MVP construction budget. As of September 30, 2018, EQM's maximum financial statement exposure related to the MVP Joint Venture was approximately $1,391 million, which consists of the investment in nonconsolidated entity balance on the Condensed Consolidated Balance Sheet as of September 30, 2018 and amounts that could have become due under EQM's performance guarantee as of that date. Following the completion of the Separation, EQM expects the MVP Joint Venture guarantee will be approximately $345 million based on MVP Holdco's share of the estimated remaining MVP construction budget and terms of the agreement.

In April 2018, the MVP Joint Venture announced the MVP Southgate project, a proposed 70-mile interstate pipeline that will extend from the MVP at Pittsylvania County, Virginia to new delivery points in Rockingham and Alamance Counties, North Carolina. This MVP Southgate project is anchored by a firm capacity commitment from PSNC Energy. The preliminary MVP Southgate project cost estimate is $350 million to $500 million, which is expected to be spent in 2019 and 2020. As of September 30, 2018, EQM had a 32.7% ownership interest in the MVP Southgate project and will operate the pipeline. Subject to approval by the FERC, the MVP Southgate project has a targeted in-service date of the fourth quarter 2020.