EQT Midstream Partners, LP (Details) (USD $)	12 Months Ended			0 Months Ended	1 Months Ended	12 Months Ended			0 Months Ended		0 Months Ended		12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Jul. 02, 2012 Performance awards	Jul. 31, 2012 Performance awards	Dec. 31, 2013 Performance awards	Dec. 31, 2013 Phantom units	Dec. 31, 2012 Phantom units	Jul. 02, 2012 Line of credit	Jul. 02, 2012 Equitrans	Jul. 22, 2013 EQT Midstream Partners	Jul. 02, 2012 EQT Midstream Partners	Dec. 31, 2013 EQT Midstream Partners	Dec. 31, 2012 EQT Midstream Partners
Subsidiary or equity method investee
Number of common units issued to the public in an offering (in shares)											12,650,000	14,375,000
Common units issued to the public in an offering as a percentage of outstanding equity												40.60%
Ownership percentage											44.60%	59.40%
Common units (in shares)											3,443,902	2,964,718
Subordinated units (in shares)											17,339,718	17,339,718
General partner's interest (as a percent)											2.00%	2.00%
Percentage of ownership contributed										100.00%
Additional borrowing									$ 350,000,000
Reversal of net deferred tax liability	5,400,000
Number of shares granted				146,490	146,490	142,500	3,790	4,780
Proceeds from offerings, net of underwriters' discount and estimated offering expenses	529,442,000	276,780,000									529,400,000	277,000,000
Portion of proceeds from IPO that are distributed to parent												231,000,000
Amount retained to replenish amounts distributed by Equitrans to EQT												12,000,000
Amount retained to pre-fund maintenance capital expenditures												32,000,000
Payment of revolving credit facility origination fees		4,022,000	11,738,000									2,000,000
Offering expenses											20,900,000
Net income attributable to noncontrolling interests	47,243,000	13,016,000											47,200,000	13,000,000
Distributions paid to noncontrolling interest	$ 32,781,000	$ 5,031,000											$ 32,800,000	$ 5,000,000
Distributions to noncontrolling interests (in dollars per common unit)	$ 1.55	$ 0.35											$ 1.55	$ 0.35