Natural Gas Producing Activities (Unaudited) - Results of Operations Related to Natural Gas, NGL and Oil Production (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Revenues:
Production costs	$ 182,737	$ 174,826	$ 177,935
Exploration costs	25,117	13,410	61,970
Impairment of long-lived assets	0	66,687	122,469
EQT Production
Revenues:
Nonaffiliated	2,651,318	1,594,997	1,690,360
Production costs	1,338,069	1,055,017	877,194
Exploration costs	25,117	13,410	61,970
Depreciation, depletion and accretion	982,103	859,018	765,298
Impairment of long-lived assets	0	6,939	122,469
Amortization of intangible assets	5,540	0	0
Income tax expense (benefit)	117,984	(136,323)	(54,857)
Results of operations from producing activities (excluding corporate overhead)	$ 182,505	$ (203,064)	$ (81,714)