Summary of Significant Accounting Policies - Schedule of Property, Plant and Equipment (Details) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Property, Plant and Equipment [Line Items]
Oil and gas producing properties, successful efforts method	$ 11,816,769	$ 10,082,825	$ 8,152,951
Accumulated depreciation and depletion	(3,425,618)	(2,693,535)	(2,134,953)
Net capitalized costs	8,391,151	7,389,290	$ 6,017,998
Midstream plant	15,635,549	13,427,429
Accumulated depreciation and amortization	(4,163,528)	(3,350,615)
Net property, plant and equipment	11,472,021	10,076,814
EQT Midstream
Property, Plant and Equipment [Line Items]
Midstream plant	3,703,994	3,234,370
Accumulated depreciation and amortization	(685,398)	(606,998)
Net property, plant and equipment	3,018,596	2,627,372
Other Properties
Property, Plant and Equipment [Line Items]
Net property, plant and equipment	$ 62,274	$ 60,152