Summary of Significant Accounting Policies - Schedule of Property, Plant and Equipment (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Property, Plant and Equipment [Line Items]
Oil and gas producing properties, successful efforts method	$ 23,937,154	$ 13,878,659	$ 11,816,769
Accumulated depreciation and depletion	(5,121,646)	(4,217,154)	(3,425,618)
Net capitalized costs	18,815,508	9,661,505	$ 8,391,151
Transmission assets	30,990,309	18,216,775
Accumulated depreciation and amortization	(6,105,294)	(5,054,559)
Net property, plant and equipment	24,885,015	13,162,216
EQT Gathering
Property, Plant and Equipment [Line Items]
Transmission assets	2,765,763	1,330,998
Accumulated depreciation and amortization	(151,595)	(110,473)
Net property, plant and equipment	2,614,168	1,220,525
EQT Transmission and Storage
Property, Plant and Equipment [Line Items]
Transmission assets	1,674,080	1,563,860
Accumulated depreciation and amortization	(248,474)	(205,551)
Net property, plant and equipment	1,425,606	1,358,309
RMP Water
Property, Plant and Equipment [Line Items]
Transmission assets	193,825	0
Accumulated depreciation and amortization	(3,363)	0
Net property, plant and equipment	190,462	0
Other Properties
Property, Plant and Equipment [Line Items]
Net property, plant and equipment	$ 1,839,271	$ 921,877