STATEMENTS OF CONSOLIDATED EQUITY - USD ($) shares in Thousands, $ in Thousands		Total	Natural Gas	Interest Rate	Cumulative Effect, Period of Adoption, Adjustment	Common Stock	Treasury Stock	Retained Earnings	Retained Earnings Cumulative Effect, Period of Adoption, Adjustment	Accumulated Other Comprehensive (Loss) Income	Accumulated Other Comprehensive (Loss) Income Natural Gas	Accumulated Other Comprehensive (Loss) Income Interest Rate	Noncontrolling Interests in Consolidated Subsidiaries
Increase (Decrease) in Stockholders' Equity
Change in accounting principle		$ 18,414,613				$ 9,388,903	$ (63,602)	$ 3,996,775		$ (2,458)			$ 5,094,995
Beginning Balance (in shares) at Dec. 31, 2017						264,320
Beginning Balance at Dec. 31, 2017		18,414,613				$ 9,388,903	(63,602)	3,996,775		(2,458)			5,094,995
Increase (Decrease) in Stockholders' Equity
Net (loss) income		(2,007,158)						(2,244,568)					237,410
Net change in cash flow hedges:			$ (4,625)	$ 168							$ (4,625)	$ 168
Other postretirement benefits liability adjustment, net of tax		606								606
Dividends		(31,375)						(31,375)
Stock-based compensation plans, net (in shares)						798
Share-based compensation plans, net		8,385				$ (6,976)	14,408						953
Distributions to noncontrolling interests in discontinued operations	[1]	(380,651)											(380,651)
Change in accounting principle		10,958,229			$ 4,113	$ 7,828,554	(49,194)	3,184,275	$ 4,113	(5,406)			0
Change in accounting principle		0
Repurchase and retirement of common stock (in shares)						(10,646)
Repurchase and retirement of common stock		(538,876)				$ (538,876)
Purchase of Strike Force Midstream LLC noncontrolling interests		(175,000)				1,818							(176,818)
Changes in ownership of consolidated subsidiaries		56,370				(158,560)							214,930
Distribution of Equitrans Midstream Corporation		(4,388,341)				$ (857,755)		1,459,330		903			(4,990,819)
Ending Balance (in shares) at Dec. 31, 2018						254,472
Ending Balance at Dec. 31, 2018		10,958,229			4,113	$ 7,828,554	(49,194)	3,184,275	4,113	(5,406)			0
Increase (Decrease) in Stockholders' Equity
Change in accounting principle		10,958,229			4,113	$ 7,828,554	(49,194)	3,184,275	4,113	(5,406)			0
Net (loss) income		(1,221,695)						(1,221,695)
Net change in cash flow hedges:			0	387								$ 387
Other postretirement benefits liability adjustment, net of tax		316								316
Dividends		(30,655)						(30,655)
Stock-based compensation plans, net (in shares)						921
Share-based compensation plans, net		23,042				$ 6,355	16,687
Change in accounting principle		10,958,229			$ 4,113	7,818,205	(32,507)	2,023,089	$ 4,113	(5,199)			0
Change in accounting principle		$ (496)						496		(496)
Accounting Standards Update [Extensible List]		us-gaap:AccountingStandardsUpdate201812Member
Distribution of Equitrans Midstream Corporation		$ 90,889				$ (2,234)		93,123
Other (in shares)						(222)
Other		(16,925)				$ (14,470)		(2,455)
Ending Balance (in shares) at Dec. 31, 2019						255,171
Ending Balance at Dec. 31, 2019		9,803,588				$ 7,818,205	(32,507)	2,023,089		(5,199)			0
Increase (Decrease) in Stockholders' Equity
Change in accounting principle		9,803,588				$ 7,818,205	(32,507)	2,023,089		(5,199)			0
Net (loss) income		(967,176)						(967,166)					(10)
Net change in cash flow hedges:			$ 0	$ 0
Other postretirement benefits liability adjustment, net of tax		(156)								(156)
Dividends		(7,664)						(7,664)
Stock-based compensation plans, net (in shares)						174
Share-based compensation plans, net		22,070				$ 18,911	3,159
Change in accounting principle		9,803,588				8,241,684	(29,348)	1,048,259		(5,355)			7,490
Change in accounting principle		0
Equity component of convertible senior notes (see Note 10)		63,645				$ 63,645
Issuance of common shares (in shares)						23,000
Issuance of common shares		340,923				$ 340,923
Contributions from noncontrolling interests		7,500											7,500
Ending Balance (in shares) at Dec. 31, 2020						278,345
Ending Balance at Dec. 31, 2020		9,262,730				$ 8,241,684	(29,348)	1,048,259		(5,355)			7,490
Increase (Decrease) in Stockholders' Equity
Change in accounting principle		$ 9,262,730				$ 8,241,684	$ (29,348)	$ 1,048,259		$ (5,355)			$ 7,490

[1] For the year ended December 31, 2018, distributions to noncontrolling interests were $4.295, $1.123 and $0.5966 per common unit for EQM Midstream Partners, LP, EQGP Holdings, LP and RM Partners LP, respectively.