Investment Nonconsolidated Entity (Details) $ in Millions			1 Months Ended	3 Months Ended
	May 12, 2017 USD ($)	Apr. 13, 2017 USD ($)	Feb. 28, 2017 USD ($)	Mar. 31, 2017 USD ($) Bcf / d mi	Mar. 31, 2016 USD ($)
Schedule of Equity Method Investments [Line Items]
Percent interest to require approval				66.67%
Issuance of performance guarantee				$ 91.0
Mountain Valley Pipeline
Schedule of Equity Method Investments [Line Items]
Natural gas interstate pipeline (in miles) | mi				300
MVP Joint Venture
Schedule of Equity Method Investments [Line Items]
Firms capacity commitments per day (in bcf per day) | Bcf / d				2.0
Duration of firm capacity commitments (in years)				20 years
EQM
Schedule of Equity Method Investments [Line Items]
Total investments				$ 4.3	$ 1.6
EQT Corporation and Subsidiaries | MVP Joint Venture
Schedule of Equity Method Investments [Line Items]
Firms capacity commitments per day (in bcf per day) | Bcf / d				1.29
MVP Joint Venture
Schedule of Equity Method Investments [Line Items]
Capital call notice			$ 40.2
MVP Joint Venture | Scenario, Forecast
Schedule of Equity Method Investments [Line Items]
Payments to acquire equity method investments	$ 18.1
MVP Joint Venture | Subsequent Event
Schedule of Equity Method Investments [Line Items]
Payments to acquire equity method investments		$ 22.1
Variable Interest Entity, Not Primary Beneficiary | MVP Joint Venture
Schedule of Equity Method Investments [Line Items]
Maximum financial statement exposure				$ 328.3
Variable Interest Entity, Not Primary Beneficiary | MVP Joint Venture | Mountain Valley Pipeline
Schedule of Equity Method Investments [Line Items]
Percentage of remaining obligations				33.00%
Variable Interest Entity, Not Primary Beneficiary | EQM | MVP Joint Venture
Schedule of Equity Method Investments [Line Items]
Ownership percentage				45.50%