EQT Midstream Partners, LP (Details) (USD $)	0 Months Ended		3 Months Ended		9 Months Ended
	Jul. 22, 2013	Jul. 02, 2012	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Subsidiary or equity method investee
Proceeds from offerings, net of underwriters' discount and estimated offering expenses					$ 529,442,000	$ 276,780,000
Net income to noncontrolling interests			14,354,000	4,831,000	30,642,000	4,831,000
Distributions paid to noncontrolling interest					21,160,000
Distributions to noncontrolling interests (in dollars per common unit)					$ 1.12
Sunrise
Subsidiary or equity method investee
Cash received	507,500,000
Taxable gain for federal income tax purposes recognized					475,000,000
Increase in cash taxes					57,000,000
Equitrans
Subsidiary or equity method investee
Percentage of ownership contributed		100.00%
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%
Proceeds from offerings, net of underwriters' discount and estimated offering expenses	529,400,000
Offering expenses	21,000,000
Net income to noncontrolling interests			14,354,000	4,831,000	30,642,000	4,831,000
Distributions paid to noncontrolling interest			10,800,000		21,200,000
Distributions to noncontrolling interests (in dollars per common unit)			$ 0.40		$ 1.12
EQT Midstream Partners | Sunrise
Subsidiary or equity method investee
Common units issued	479,184
General partner units issued	267,942
Term of the transportation precedent agreement	20 years
Additional cash consideration related to the transportation precedent agreement	$ 110,000,000