Financial Information by Business Segment - Schedule of Revenue from External Customers and Operating Income (Details) $ in Thousands		3 Months Ended		6 Months Ended
	Nov. 12, 2017 segment	Jun. 30, 2018 USD ($)	Jun. 30, 2017 USD ($)	Jun. 30, 2018 USD ($) segment	Jun. 30, 2017 USD ($)	Dec. 31, 2017 USD ($)	Nov. 13, 2017 USD ($)
Operating segments information
Number of reportable segments | segment	3			5
Goodwill		$ 1,998,726		$ 1,998,726		$ 1,998,726
Revenues:
Sales of natural gas, oil and NGLs		1,104,779		2,454,977
(Loss) gain on derivatives not designated as hedges		(53,897)	$ 46,326	8,695	$ 187,068
Total operating revenues		1,054,671	688,742	2,488,254	1,582,911
Reconciliation of operating (loss) income to net (loss) income:
Total operating income (loss)		99,969	190,127	(1,623,547)	581,103
Other income		11,752	6,305	21,337	9,354
Interest expense		77,004	44,078	147,017	86,733
Income tax (benefit) expense		(101,629)	29,709	(440,594)	130,374
Net income (loss)		136,346	122,645	(1,308,633)	373,350
Transaction costs		25,959	4,238	61,670	4,238
Sales of natural gas, oil and NGLs
Revenues:
Sales of natural gas, oil and NGLs		991,365	576,714	2,217,739	1,250,179
Pipeline, water and net marketing services
Revenues:
Pipeline, water and net marketing services		117,203	65,702	261,820	145,664
EQT Production
Reconciliation of operating (loss) income to net (loss) income:
Impairment of long-lived assets		100,000		2,400,000
Operating Segments | EQT Production
Revenues:
(Loss) gain on derivatives not designated as hedges		(53,897)	46,326	8,695	187,068
Total operating revenues		950,648	631,101	2,262,684	1,459,763
Reconciliation of operating (loss) income to net (loss) income:
Total operating income (loss)		(79,846)	52,884	(2,005,645)	310,433
Operating Segments | EQT Production | Sales of natural gas, oil and NGLs
Revenues:
Sales of natural gas, oil and NGLs		991,365	576,714	2,217,739	1,250,179
Operating Segments | EQT Production | Pipeline, water and net marketing services
Revenues:
Pipeline, water and net marketing services		13,180	8,061	36,250	22,516
Operating Segments | EQM Gathering
Revenues:
(Loss) gain on derivatives not designated as hedges		0	0	0	0
Total operating revenues		180,616	112,145	360,244	214,474
Reconciliation of operating (loss) income to net (loss) income:
Total operating income (loss)		121,631	83,425	252,513	157,129
Operating Segments | EQM Gathering | Sales of natural gas, oil and NGLs
Revenues:
Sales of natural gas, oil and NGLs		0	0	0	0
Operating Segments | EQM Gathering | Pipeline, water and net marketing services
Revenues:
Pipeline, water and net marketing services		180,616	112,145	360,244	214,474
Operating Segments | EQM Transmission
Revenues:
(Loss) gain on derivatives not designated as hedges		0	0	0	0
Total operating revenues		89,145	84,670	196,079	182,413
Reconciliation of operating (loss) income to net (loss) income:
Total operating income (loss)		60,642	57,863	140,093	129,467
Operating Segments | EQM Transmission | Sales of natural gas, oil and NGLs
Revenues:
Sales of natural gas, oil and NGLs		0	0	0	0
Operating Segments | EQM Transmission | Pipeline, water and net marketing services
Revenues:
Pipeline, water and net marketing services		89,145	84,670	196,079	182,413
Operating Segments | RMP Gathering
Revenues:
(Loss) gain on derivatives not designated as hedges		0		0
Total operating revenues		62,281		123,782
Reconciliation of operating (loss) income to net (loss) income:
Total operating income (loss)		39,614	0	83,709	0
Operating Segments | RMP Gathering | Sales of natural gas, oil and NGLs
Revenues:
Sales of natural gas, oil and NGLs		0		0
Operating Segments | RMP Gathering | Pipeline, water and net marketing services
Revenues:
Pipeline, water and net marketing services		62,281		123,782
Operating Segments | RMP Water
Revenues:
(Loss) gain on derivatives not designated as hedges		0		0
Total operating revenues		42,655		65,618
Reconciliation of operating (loss) income to net (loss) income:
Total operating income (loss)		23,981	0	35,351	0
Operating Segments | RMP Water | Sales of natural gas, oil and NGLs
Revenues:
Sales of natural gas, oil and NGLs		0		0
Operating Segments | RMP Water | Pipeline, water and net marketing services
Revenues:
Pipeline, water and net marketing services		42,655		65,618
Intersegment Eliminations
Revenues:
Sales of natural gas, oil and NGLs		(270,674)		(520,153)
(Loss) gain on derivatives not designated as hedges		0	0	0	0
Total operating revenues		(270,674)	(139,174)	(520,153)	(273,739)
Intersegment Eliminations | Sales of natural gas, oil and NGLs
Revenues:
Sales of natural gas, oil and NGLs		0	0	0	0
Intersegment Eliminations | Pipeline, water and net marketing services
Revenues:
Pipeline, water and net marketing services		(270,674)	(139,174)	(520,153)	(273,739)
Unallocated Expenses
Reconciliation of operating (loss) income to net (loss) income:
Total operating income (loss)		(66,053)	$ (4,045)	(129,568)	$ (15,926)
Transaction costs		19,700		54,500
Income (loss) included in development costs		$ 24,900		$ 47,500
Previously Reported | Rice Merger Agreement
Operating segments information
Goodwill							$ 78,400