Financial Information by Business Segment - Schedule of Operating Revenue by Segment (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Segment Reporting Information [Line Items]
Sales of natural gas, oil and NGLs									$ 2,651,318	$ 1,594,997	$ 1,690,360
Pipeline, water and net marketing services									336,676	262,342	263,640
Gain (loss) on derivatives not designated as hedges									390,021	(248,991)	385,762
Operating revenues	$ 1,129,286	$ 660,313	$ 690,893	$ 897,523	$ 379,022	$ 556,726	$ 127,531	$ 545,069	3,378,015	1,608,348	2,339,762
Operating Segments | EQT Production
Segment Reporting Information [Line Items]
Sales of natural gas, oil and NGLs									2,651,318	1,594,997	1,690,360
Pipeline, water and net marketing services									64,998	41,048	55,542
Gain (loss) on derivatives not designated as hedges									390,021	(248,991)	385,762
Operating revenues									3,106,337	1,387,054	2,131,664
Operating Segments | EQT Gathering
Segment Reporting Information [Line Items]
Sales of natural gas, oil and NGLs									0	0	0
Pipeline, water and net marketing services									454,536	397,494	335,105
Gain (loss) on derivatives not designated as hedges									0	0	0
Operating revenues									454,536	397,494	335,105
Operating Segments | EQT Transmission and Storage
Segment Reporting Information [Line Items]
Sales of natural gas, oil and NGLs									0	0	0
Pipeline, water and net marketing services									379,560	338,120	297,831
Gain (loss) on derivatives not designated as hedges									0	0	0
Operating revenues									379,560	338,120	297,831
Operating Segments | RMP Gathering
Segment Reporting Information [Line Items]
Sales of natural gas, oil and NGLs									0
Pipeline, water and net marketing services									30,614
Gain (loss) on derivatives not designated as hedges									0
Operating revenues									30,614
Operating Segments | RMP Water
Segment Reporting Information [Line Items]
Sales of natural gas, oil and NGLs									0
Pipeline, water and net marketing services									13,605
Gain (loss) on derivatives not designated as hedges									0
Operating revenues									13,605
Intersegment Eliminations
Segment Reporting Information [Line Items]
Sales of natural gas, oil and NGLs									0	0	0
Pipeline, water and net marketing services									(606,637)	(514,320)	(424,838)
Gain (loss) on derivatives not designated as hedges									0	0	0
Operating revenues									$ (606,637)	$ (514,320)	$ (424,838)