Share-Based Compensation Plans - Schedule of Executive Performance Incentive Programs (Details) - USD ($)	1 Months Ended	4 Months Ended	12 Months Ended
	Apr. 30, 2022	Apr. 30, 2022	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Incentive PSU Programs – Equity Settled
Aggregate Fair Value
Increase in weighted average grant date fair value (in dollars per share)		$ 45.59
Performance Shares | Incentive PSU Programs – Equity Settled
Non- Vested Shares
Non-vested shares, outstanding, beginning balance (in shares)		2,754,648	2,754,648	1,939,728	615,293
Non-vested shares, granted in period (in shares)			575,120	922,260	1,376,198
Non-vested shares, granted from multiplier (in shares)			162,183	61,076	28,705
Non-vested shares, vested (in shares)			(625,563)	(168,416)	(73,278)
Non-vested shares, forfeited (in shares)			(4,398)		(7,190)
Non-vested shares, outstanding, ending balance (in shares)			2,861,990	2,754,648	1,939,728
Weighted Average Fair Value
Weighted average fair value, outstanding, beginning balance (in dollars per share)		$ 16.08	$ 16.08	$ 15.92	$ 44.27
Weighted average fair value, granted in period (in dollars per share)	$ 75.32		29.73	23.44	6.62
Weighted average fair value, granted from multiplier(in dollars per share)			29.45	76.53	120.60
Weighted average fair value, vested (in dollars per share)			29.45	76.53	120.60
Weighted average fair value, forfeited (in dollars per share)			13.28		13.28
Weighted average fair value, outstanding, ending balance (in dollars per share)			$ 16.66	$ 16.08	$ 15.92
Aggregate Fair Value
Aggregate fair value, beginning balance		$ 44,281,509	$ 44,281,509	$ 30,878,465	$ 27,239,021
Aggregate fair value, granted			17,098,318	21,617,774	9,110,431
Aggregate fair value, granted from multiplier			4,776,289	4,674,146	3,461,823
Aggregate fair value, vested			(18,422,830)	(12,888,876)	(8,837,327)
Aggregate fair value, forfeited			(58,405)		(95,483)
Aggregate fair value, ending balance			$ 47,674,881	$ 44,281,509	$ 30,878,465
Performance Shares | Incentive PSU Programs – Equity Settled | Equitrans Midstream Employees
Non- Vested Shares
Non-vested shares, outstanding, beginning balance (in shares)		9,550	9,550	7,020
Non-vested shares, outstanding, ending balance (in shares)				9,550	7,020
Performance Shares | Incentive PSU Programs – Cash Settled
Non- Vested Shares
Non-vested shares, outstanding, beginning balance (in shares)		233,580	233,580	339,695	452,410
Non-vested shares, granted from multiplier (in shares)			81,753	32,350	60,123
Non-vested shares, vested (in shares)			(315,333)	(134,525)	(153,482)
Non-vested shares, forfeited (in shares)				(3,940)	(19,356)
Non-vested shares, outstanding, ending balance (in shares)			0	233,580	339,695
Weighted Average Fair Value
Weighted average fair value, outstanding, beginning balance (in dollars per share)		$ 29.32	$ 29.32	$ 43.52	$ 60.19
Weighted average fair value, granted from multiplier(in dollars per share)			29.32	76.53	120.60
Weighted average fair value, vested (in dollars per share)			29.32	76.53	120.60
Weighted average fair value, forfeited (in dollars per share)				29.45	61.43
Weighted average fair value, outstanding, ending balance (in dollars per share)			$ 0	$ 29.32	$ 43.52
Aggregate Fair Value
Aggregate fair value, beginning balance		$ 6,848,566	$ 6,848,566	$ 14,782,424	$ 27,230,558
Aggregate fair value, granted from multiplier			2,396,998	2,475,746	7,250,834
Aggregate fair value, vested			(9,245,564)	(10,293,571)	(18,509,929)
Aggregate fair value, forfeited				(116,033)	(1,189,039)
Aggregate fair value, ending balance			$ 0	$ 6,848,566	$ 14,782,424