EQM Midstream Partners 10-Q 5 Nov 19 2019 Q3 Quarterly report Financial data

Cover

Cover - shares	9 Months Ended
	Sep. 30, 2019	Oct. 31, 2019
Document Information [Line Items]
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Sep. 30, 2019
Document Transition Report	false
Entity File Number	001-35574
Entity Registrant Name	EQM Midstream Partners, LP
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	37-1661577
Entity Address, Address Line One	2200 Energy Drive
Entity Address, City or Town	Canonsburg
Entity Address, State or Province	PA
Entity Address, Postal Zip Code	15317
City Area Code	724
Local Phone Number	271-7600
Title of 12(b) Security	Common Units Representing Limited Partner Interests
Trading Symbol	EQM
Security Exchange Name	NYSE
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Emerging Growth Company	false
Small Business Entity	false
Entity Shell Company	false
Entity Common Units, Unit Outstanding (in shares)		200,457,630
Entity Central Index Key	0001540947
Amendment Flag	false
Current Fiscal Year End	--12-31
Document Fiscal Year Focus	2019
Document Fiscal Period Focus	Q3
Class B Units
Document Information [Line Items]
Entity Common Units, Unit Outstanding (in shares)		7,000,000
Former Address
Document Information [Line Items]
Entity Address, Address Line One	625 Liberty Avenue, Suite 2000
Entity Address, City or Town	Pittsburgh
Entity Address, State or Province	PA
Entity Address, Postal Zip Code	15222

Statements of Consolidated Oper

Statements of Consolidated Operations (Unaudited) - USD ($) shares in Thousands, $ in Thousands		3 Months Ended				9 Months Ended
		Sep. 30, 2019		Sep. 30, 2018		Sep. 30, 2019		Sep. 30, 2018
Income Statement [Abstract]
Operating revenues	[1],[2]	$ 408,434		$ 364,584		$ 1,204,383		$ 1,110,307
Operating expenses:
Operating and maintenance	[1],[3]	43,021		48,109		117,460		118,775
Selling, general and administrative	[1],[3]	23,845		26,860		83,171		80,738
Separation and other transaction costs	[1]	256		2,161		19,127		7,511
Depreciation	[1]	59,197		43,567		162,777	[4]	126,957	[4]
Amortization of intangible assets	[1]	14,540		10,387		38,677	[4]	31,160	[4]
Impairments of long-lived assets	[1],[5]	298,652		0		378,787	[6]	0	[6]
Total operating expenses	[1]	439,511		131,084		799,999		365,141
Operating (loss) income	[1]	(31,077)		233,500		404,384		745,166
Equity income	[1],[7]	44,448		16,087		112,293	[4]	35,836	[4]
Other income	[1]	337		1,345		4,506		3,193
Net interest expense	[1],[8]	53,923		41,005		152,996		76,740
Net (loss) income	[1]	(40,215)	[9]	209,927	[9]	368,187	[4]	707,455	[4]
Net (loss) income attributable to noncontrolling interests	[1]	(29,697)		0		(25,664)		3,346
Net (loss) income attributable to EQM	[1]	(10,518)		209,927		393,851		704,109
Calculation of limited partner common unit interest in net (loss) income:
Net (loss) income attributable to EQM	[1]	(10,518)		209,927		393,851		704,109
Less: Series A Preferred Units interest in net income	[1]	(25,501)		0		(48,480)		0
Less: pre-acquisition net income allocated to EQT	[1]	0		(8,490)		0		(164,242)
Less: general partner interest in net income – general partner units	[1]	0		(2,379)		0		(7,145)
Less: general partner interest in net income – IDRs	[1]	0		(70,967)		0		(183,253)
Limited partner interest in net (loss) income	[1]	$ (36,019)		$ 128,091		$ 345,371		$ 349,469
Net (loss) income per limited partner common unit – basic (in dollars per share)	[1],[10]	$ (0.18)		$ 1.14		$ 1.86		$ 3.73
Net (loss) income per limited partner common unit – diluted (in dollars per share)	[1],[10]	$ (0.18)		$ 1.14		$ 1.80		$ 3.73
Weighted average limited partner common units outstanding – basic (in shares)	[1]	200,483		111,980		185,244		93,746
Weighted average limited partner common units outstanding – diluted (in shares)	[1]	200,483		111,980		192,244		93,746
Cash distributions declared per unit (in dollars per share)	[1],[11]	$ 1.160		$ 1.115		$ 3.465		$ 3.270
[1]	As discussed in Notes 1 and 2 , the consolidated financial statements of EQM have been retrospectively recast to include the pre-acquisition results of EQM Olympus Midstream LLC (EQM Olympus), Strike Force Midstream Holdings LLC (Strike Force) and EQM West Virginia Midstream LLC (EQM WV), which were acquired by EQM effective on May 1, 2018 (the Drop-Down Transaction), and RM Partners LP (RMP), which was acquired by EQM effective on July 23, 2018 (the EQM-RMP Merger), because these transactions were between entities under common control.
[2]	Operating revenues included related party revenues from EQT Corporation (NYSE: EQT) (EQT) of $275.4 million and $276.9 million for the three months ended September 30, 2019 and 2018 , respectively, and $843.9 million and $827.8 million for the nine months ended September 30, 2019 and 2018 , respectively. See Note 8 .
[3]	For the three and nine months ended September 30, 2019 , operating and maintenance expense included $15.4 million and $41.6 million of charges from Equitrans Midstream Corporation (NYSE: ETRN) (Equitrans Midstream), respectively. For the three and nine months ended September 30, 2018 , operating and maintenance expense included charges from EQT of $14.0 million and $38.4 million , respectively. For the three and nine months ended September 30, 2019 , selling, general and administrative expense included charges from Equitrans Midstream of $16.0 million and $67.4 million , respectively. For the three and nine months ended September 30, 2018 , selling, general and administrative expense included charges from EQT of $25.7 million and $75.1 million , respectively. See Note 8 .
[4]	As discussed in Notes 1 and 2 , the consolidated financial statements of EQM have been retrospectively recast to include the pre-acquisition results of the Drop-Down Transaction and the EQM-RMP Merger because these transactions were between entities under common control.
[5]	See Note 3 for disclosure regarding impairments of long-lived assets.
[6]	See Note 3 for disclosure regarding impairments of long-lived assets.
[7]	Represents equity income from Mountain Valley Pipeline, LLC (the MVP Joint Venture). See Note 9 .
[8]	Net interest expense included interest income on the Preferred Interest in EQT Energy Supply, LLC (EES), a subsidiary of EQT, of $1.6 million and $1.6 million for the three months ended September 30, 2019 and 2018 , respectively, and $4.8 million and $5.0 million for the nine months ended September 30, 2019 and 2018 , respectively.
[9]	As discussed in Notes 1 and 2 , the consolidated financial statements of EQM have been retrospectively recast to include the pre-acquisition results of the Drop-Down Transaction and the EQM-RMP Merger because these transactions were between entities under common control.
[10]	See Note 12 for disclosure regarding EQM's calculation of net income per limited partner unit (basic and diluted).
[11]	Represents the cash distributions declared related to the period presented. See Note 12 .

Statements of Consolidated Op_2

Statements of Consolidated Operations (Unaudited) (Parenthetical) - USD ($) $ in Thousands		3 Months Ended		9 Months Ended
		Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Operating and maintenance	[1],[2]	$ 43,021	$ 48,109	$ 117,460	$ 118,775
Selling, general and administrative expenses	[1],[2]	23,845	26,860	83,171	80,738
EQT
Operating revenues		275,400	276,900	843,900	827,800
Operating and maintenance			14,000		38,400
Selling, general and administrative expenses			25,700		75,100
EES
Interest income		1,600	$ 1,600	4,800	$ 5,000
ETRN
Operating and maintenance		15,400		41,600
Selling, general and administrative expenses		$ 16,000		$ 67,400
[1]	As discussed in Notes 1 and 2 , the consolidated financial statements of EQM have been retrospectively recast to include the pre-acquisition results of EQM Olympus Midstream LLC (EQM Olympus), Strike Force Midstream Holdings LLC (Strike Force) and EQM West Virginia Midstream LLC (EQM WV), which were acquired by EQM effective on May 1, 2018 (the Drop-Down Transaction), and RM Partners LP (RMP), which was acquired by EQM effective on July 23, 2018 (the EQM-RMP Merger), because these transactions were between entities under common control.
[2]	For the three and nine months ended September 30, 2019 , operating and maintenance expense included $15.4 million and $41.6 million of charges from Equitrans Midstream Corporation (NYSE: ETRN) (Equitrans Midstream), respectively. For the three and nine months ended September 30, 2018 , operating and maintenance expense included charges from EQT of $14.0 million and $38.4 million , respectively. For the three and nine months ended September 30, 2019 , selling, general and administrative expense included charges from Equitrans Midstream of $16.0 million and $67.4 million , respectively. For the three and nine months ended September 30, 2018 , selling, general and administrative expense included charges from EQT of $25.7 million and $75.1 million , respectively. See Note 8 .

Statements of Consolidated Cash

Statements of Consolidated Cash Flows (Unaudited) - USD ($) $ in Thousands		9 Months Ended
		Sep. 30, 2019	Sep. 30, 2018
Cash flows from operating activities:
Net income	[1],[2]	$ 368,187	$ 707,455
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation	[1],[2]	162,777	126,957
Amortization of intangible assets	[1],[2]	38,677	31,160
Impairments of long-lived assets	[1],[3],[4]	378,787	0
Equity income	[1],[2],[5]	(112,293)	(35,836)
AFUDC – equity	[2]	(4,927)	(3,585)
Non-cash long-term compensation expense	[2]	255	1,275
Changes in other assets and liabilities:
Accounts receivable	[2]	29,022	2,193
Accounts payable	[2]	(84,103)	13,443
Other assets and other liabilities	[2]	(31,555)	22,420
Net cash provided by operating activities	[2]	744,827	865,482
Cash flows from investing activities:
Capital expenditures	[2]	(824,930)	(616,365)
Capital contributions to the MVP Joint Venture	[2]	(512,852)	(446,049)
Bolt-on Acquisition (defined in Note 2), net of cash acquired	[2]	(837,231)	0
Drop-Down Transaction	[6]	0	(1,193,160)
Principal payments received on the Preferred Interest	[2]	3,471	3,281
Net cash used in investing activities	[2]	(2,171,542)	(2,252,293)
Cash flows from financing activities:
Proceeds from credit facility borrowings	[2]	1,887,000	2,524,000
Payments on credit facility borrowings	[2]	(2,227,000)	(2,968,000)
Pay-down of long-term debt associated with Bolt-on Acquisition (Note 2)		(28,325)	0
Proceeds from issuance of long-term debt	[2]	1,400,000	2,500,000
Debt discount and issuance costs	[6]	(2,563)	(34,249)
Proceeds from issuance of Series A Preferred Units, net of offering costs		1,158,313	0
Distributions paid to common unitholders	[2]	(673,347)	(528,410)
Distributions paid to Series A Preferred unitholders		(22,979)	0
Distributions paid to noncontrolling interest	[2]	0	(750)
Acquisition of 25% of Strike Force Midstream LLC	[2]	0	(175,000)
Capital contributions	[2]	0	15,672
Net contributions from EQT	[6]	0	3,660
Net cash provided by financing activities	[2]	1,491,099	1,336,923
Net change in cash and cash equivalents	[2]	64,384	(49,888)
Cash and cash equivalents at beginning of period	[2]	17,515	54,600
Cash and cash equivalents at end of period	[2]	81,899	4,712
Cash paid during the period for:
Interest, net of amount capitalized	[2]	192,298	42,652
Non-cash activity during the period for:
Increase (decrease) in capital contribution receivable from Equitrans Midstream/EQT	[2]	$ 711	$ (11,758)
[1]	As discussed in Notes 1 and 2 , the consolidated financial statements of EQM have been retrospectively recast to include the pre-acquisition results of EQM Olympus Midstream LLC (EQM Olympus), Strike Force Midstream Holdings LLC (Strike Force) and EQM West Virginia Midstream LLC (EQM WV), which were acquired by EQM effective on May 1, 2018 (the Drop-Down Transaction), and RM Partners LP (RMP), which was acquired by EQM effective on July 23, 2018 (the EQM-RMP Merger), because these transactions were between entities under common control.
[2]	As discussed in Notes 1 and 2 , the consolidated financial statements of EQM have been retrospectively recast to include the pre-acquisition results of the Drop-Down Transaction and the EQM-RMP Merger because these transactions were between entities under common control.
[3]	See Note 3 for disclosure regarding impairments of long-lived assets.
[4]	See Note 3 for disclosure regarding impairments of long-lived assets.
[5]	Represents equity income from Mountain Valley Pipeline, LLC (the MVP Joint Venture). See Note 9 .
[6]	Accounts receivable as of September 30, 2019 and December 31, 2018 included approximately $175.7 million and $174.8 million , respectively, of accounts receivable due from EQT.

Statements of Consolidated Ca_2

Statements of Consolidated Cash Flows (Unaudited) (Parenthetical)	Sep. 30, 2018	Jun. 30, 2018
Statement of Cash Flows [Abstract]
Percentage of voting interests acquired	25.00%	25.00%

Consolidated Balance Sheets (Un

Consolidated Balance Sheets (Unaudited) - USD ($) $ in Thousands		Sep. 30, 2019	Dec. 31, 2018
Current assets:
Cash and cash equivalents		$ 81,899	$ 17,515
Accounts receivable (net of allowance for doubtful accounts of [$29] and $75 as of September 30, 2019 and December 31, 2018, respectively)	[1]	242,186	254,390
Other current assets		21,035	14,909
Total current assets		345,120	286,814
Property, plant and equipment		8,431,130	6,367,530
Less: accumulated depreciation		(822,713)	(560,902)
Net property, plant and equipment		7,608,417	5,806,628
Investment in unconsolidated entity		2,227,321	1,510,289
Goodwill	[2]	962,218	1,123,813
Net intangible assets		812,020	576,113
Other assets		198,941	152,464
Total assets		12,154,037	9,456,121
Current liabilities:
Accounts payable	[3]	172,422	207,877
Due to Equitrans Midstream		27,563	44,509
Capital contribution payable to the MVP Joint Venture		261,089	169,202
Accrued interest		41,170	80,199
Accrued liabilities		34,022	20,672
Total current liabilities		536,266	522,459
Credit facility borrowings	[4]	557,500	625,000
Long-term debt		4,858,208	3,456,639
Regulatory and other long-term liabilities		79,164	38,724
Total liabilities		6,031,138	4,642,822
Equity:
Series A Preferred Units		1,183,814	0
General partner		0	29,626
Noncontrolling interest	[5]	452,796	0
Total equity	[6]	6,122,899	4,813,299
Total liabilities and equity		12,154,037	9,456,121
Common Units
Equity:
Common and Class B		4,481,148	4,783,673
Class B Units
Equity:
Common and Class B		$ 5,141	$ 0
[1]	Accounts receivable as of September 30, 2019 and December 31, 2018 included approximately $175.7 million and $174.8 million , respectively, of accounts receivable due from EQT.
[2]	See Note 3 for disclosure regarding impairments of goodwill.
[3]	Accounts payable as of December 31, 2018 included approximately $34.0 million due to EQT. There was no related party balance with EQT included in accounts payable as of September 30, 2019 .
[4]	As of September 30, 2019 , EQM had credit facility borrowings outstanding of approximately $265 million and $293 million on its $3 Billion Facility and the Eureka Credit Facility, respectively (both defined herein). See Note 10 for further detail.
[5]	Noncontrolling interest as of September 30, 2019 represents third-party ownership in Eureka Midstream Holdings, LLC (Eureka Midstream). See Note 2 for further information.
[6]	As discussed in Notes 1 and 2 , the consolidated financial statements of EQM have been retrospectively recast to include the pre-acquisition results of the Drop-Down Transaction and the EQM-RMP Merger because these transactions were between entities under common control.

Consolidated Balance Sheets (_2

Consolidated Balance Sheets (Unaudited) (Parenthetical) - USD ($)		Sep. 30, 2019	Dec. 31, 2018
Accounts receivable, for doubtful accounts		$ 29,000	$ 75,000
Series A Preferred Units issued (in shares)		24,605,291	0
Series A Preferred Units outstanding (in shares)		24,605,291	0
General partner, units issued (in shares)		0	1,443,015
General partner, units outstanding (in shares)		0	1,443,015
Accounts receivable – affiliate		$ 175,700,000	$ 174,800,000
Accounts payable, related parties		0	34,000,000
Credit facility borrowings	[1]	$ 557,500,000	$ 625,000,000
Common Units
Common units issued (in shares)		200,457,630	120,457,638
Common units outstanding (in shares)		200,457,630	120,457,638
Class B Units
Common units issued (in shares)		7,000,000	0
Common units outstanding (in shares)		7,000,000	0
Line of Credit | $3 Billion Credit Facility
Credit facility borrowings		$ 265,000,000
Maximum borrowing capacity		3,000,000,000
Eureka Midstream, LLC | Line of Credit | Eureka Credit Facility
Credit facility borrowings		$ 293,000,000
[1]	As of September 30, 2019 , EQM had credit facility borrowings outstanding of approximately $265 million and $293 million on its $3 Billion Facility and the Eureka Credit Facility, respectively (both defined herein). See Note 10 for further detail.

Statements of Consolidated Equi

Statements of Consolidated Equity (Unaudited) - USD ($) $ in Thousands		Total		General Partner	Predecessor Equity	Noncontrolling Interest	Series A Preferred Units	Series A Preferred UnitsLimited Partners	Common Units	Common UnitsLimited Partners	Class B UnitsLimited Partners
Beginning balance at Dec. 31, 2017	[1]	$ 6,238,864		$ 1,252	$ 3,916,434	$ 173,472		$ 0		$ 2,147,706	$ 0
Increase (Decrease) in Partners' Capital
Net income (loss)	[1]	262,843		47,281	83,132	2,493				129,937
Capital contributions	[1]	2,799		50						2,749
Equity-based compensation plans	[1]	499			168					331
Distributions paid to unitholders	[1]	(158,735)		(43,294)	(32,845)					(82,596)
Net contributions from EQT	[1]	1,015			1,015
Distributions paid to noncontrolling interests	[1]	(750)				(750)
Ending balance at Mar. 31, 2018	[1]	6,346,535		5,289	3,967,904	175,215		0		2,198,127	0
Beginning balance at Dec. 31, 2017	[1]	6,238,864		1,252	3,916,434	173,472		0		2,147,706	0
Increase (Decrease) in Partners' Capital
Net income (loss)	[2],[3]	707,455
Ending balance at Sep. 30, 2018	[1]	5,057,851		31,420	0	0		0		5,026,431	0
Beginning balance at Mar. 31, 2018	[1]	6,346,535		5,289	3,967,904	175,215		0		2,198,127	0
Increase (Decrease) in Partners' Capital
Net income (loss)	[1]	234,685		69,795	72,620	853				91,417
Acquisition of 25% of Strike Force Midstream LLC	[1]	(175,000)				(176,068)				1,068
Drop-Down Transaction	[1]	(1,193,160)			(1,436,297)					243,137
Capital contributions	[1]	622		10						612
Equity-based compensation plans	[1]	140			140
Distributions paid to unitholders	[1]	(167,866)		(46,491)	(35,545)					(85,830)
Net contributions from EQT	[1]	2,645			2,645
Ending balance at Jun. 30, 2018	[1]	5,048,601		28,603	2,571,467	0		0		2,448,531	0
Increase (Decrease) in Partners' Capital
Net income (loss)	[1]	209,927	[2]	73,322	8,490					128,115
Capital contributions	[1]	496		6						490
Equity-based compensation plans	[1]	636			614					22
Distributions paid to unitholders	[1]	(201,809)		(70,511)						(131,298)
EQM-RMP Merger	[1]				(2,580,571)					2,580,571
Ending balance at Sep. 30, 2018	[1]	5,057,851		31,420	0	0		0		5,026,431	0
Beginning balance at Dec. 31, 2018	[1]	4,813,299		29,626	0	0		0		4,783,673	0
Increase (Decrease) in Partners' Capital
Net income (loss)	[1]	251,931		1,767						246,699	3,465
Equity-based compensation plans	[1]	255								255
Distributions paid to unitholders	[1]	(211,292)		(75,175)						(136,117)
Equity restructuring associated with the EQM IDR Transaction	[1]			43,782						(42,305)	(1,477)
Ending balance at Mar. 31, 2019	[1]	4,854,193		0	0	0		0		4,852,205	1,988
Beginning balance at Dec. 31, 2018	[1]	4,813,299		29,626	0	0		0		4,783,673	0
Increase (Decrease) in Partners' Capital
Net income (loss)	[2],[3]	368,187
Ending balance at Sep. 30, 2019	[1]	6,122,899		0	0	452,796		1,183,814		4,481,148	5,141
Beginning balance at Mar. 31, 2019	[1]	4,854,193		0	0	0		0		4,852,205	1,988
Increase (Decrease) in Partners' Capital
Net income (loss)	[1]	156,471				4,033		22,979		125,091	4,368
Capital contributions	[1]	497								497
Distributions paid to unitholders	[1]	(229,524)								(229,524)
Issuance of Series A Preferred Units, net of offering costs	[1]	1,158,313						1,158,313
Bolt-on Acquisition	[1]	486,062				486,062
Ending balance at Jun. 30, 2019	[1]	6,426,012		0	0	490,095		1,181,292		4,748,269	6,356
Increase (Decrease) in Partners' Capital
Net income (loss)	[1]	(40,215)	[2]	0		(29,697)		25,501		(34,804)	(1,215)
Capital contributions	[1]	214		0						214
Distributions paid to unitholders	[1]						$ (22,979)	(22,979)	$ (232,531)	(232,531)
Bolt-on Acquisition measurement period adjustment (Note 2)	[1]	(7,602)				(7,602)
Ending balance at Sep. 30, 2019	[1]	$ 6,122,899		$ 0	$ 0	$ 452,796		$ 1,183,814		$ 4,481,148	$ 5,141
[1]	As discussed in Notes 1 and 2 , the consolidated financial statements of EQM have been retrospectively recast to include the pre-acquisition results of the Drop-Down Transaction and the EQM-RMP Merger because these transactions were between entities under common control.
[2]	As discussed in Notes 1 and 2 , the consolidated financial statements of EQM have been retrospectively recast to include the pre-acquisition results of EQM Olympus Midstream LLC (EQM Olympus), Strike Force Midstream Holdings LLC (Strike Force) and EQM West Virginia Midstream LLC (EQM WV), which were acquired by EQM effective on May 1, 2018 (the Drop-Down Transaction), and RM Partners LP (RMP), which was acquired by EQM effective on July 23, 2018 (the EQM-RMP Merger), because these transactions were between entities under common control.
[3]	As discussed in Notes 1 and 2 , the consolidated financial statements of EQM have been retrospectively recast to include the pre-acquisition results of the Drop-Down Transaction and the EQM-RMP Merger because these transactions were between entities under common control.

Statements of Consolidated Eq_2

Statements of Consolidated Equity (Unaudited) (Parenthetical)	3 Months Ended
	Sep. 30, 2019$ / shares
Distributions paid to unitholders (dollars per common unit)	$ 1,160
Series A Preferred Units
Distributions paid to unitholders (dollars per common unit)	$ 933.9000

Financial Statements

Financial Statements	9 Months Ended
	Sep. 30, 2019
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Financial Statements	Financial Statements Organization EQM is a growth-oriented Delaware limited partnership formed by EQT in January 2012. Prior to the completion of the EQM IDR Transaction (defined below), EQM Midstream Services, LLC was the general partner of EQM (the Former EQM General Partner). Following the consummation of the EQM IDR Transaction, EQGP Services, LLC, a wholly-owned indirect subsidiary of Equitrans Midstream, became the general partner of EQM (the New EQM General Partner). References in these consolidated financial statements to Equitrans Midstream refer collectively to Equitrans Midstream Corporation and its consolidated subsidiaries, as applicable. On February 21, 2018, EQT announced its plan to separate its midstream business, which was composed of the separately-operated natural gas gathering, transmission and storage and water services operations of EQT (collectively, the Midstream Business), from its upstream business, which was composed of the natural gas, oil and natural gas liquids development, production and sales and commercial operations of EQT (collectively, the Upstream Business) (the Separation). On November 12, 2018, the Separation was effected through a series of transactions that culminated in EQT's contribution of the Midstream Business to Equitrans Midstream. On February 22, 2019, Equitrans Midstream completed a simplification transaction pursuant to that certain Agreement and Plan of Merger, dated as of February 13, 2019 (the IDR Merger Agreement), by and among Equitrans Midstream and certain related parties, pursuant to which, among other things, (i) Equitrans Merger Sub, LP, a party to the IDR Merger Agreement, merged with and into EQGP (the Merger) with EQGP continuing as the surviving limited partnership and a wholly-owned subsidiary of EQM following the Merger, and (ii) each of (a) the IDRs, (b) the economic portion of the general partner interest in EQM and (c) the issued and outstanding EQGP common units representing limited partner interests in EQGP were canceled, and, as consideration for such cancellation, certain affiliates of Equitrans Midstream received on a pro rata basis 80,000,000 newly-issued EQM common units and 7,000,000 newly-issued Class B units (Class B units), both representing limited partner interests in EQM, and the New EQM General Partner retained the non-economic general partner interest in EQM (the EQM IDR Transaction). Additionally, as part of the EQM IDR Transaction, the 21,811,643 EQM common units held by EQGP were canceled and 21,811,643 EQM common units were issued pro rata to certain affiliates of Equitrans Midstream. See Note 5 for further information on the EQM IDR Transaction and Class B Units. The EQM IDR Transaction constituted an exchange of equity interests between entities under common control and not a transfer of a business. Therefore, the exchange resulted in a reclassification, as of February 22, 2019, of a $43.8 million deficit capital balance from the general partner line item to the common and Class B line items in EQM's consolidated balance sheets based on the respective limited partner ownership interests. The reclassification represented an allocation of the carrying value of the exchanged general partner interest. Prior to the EQM IDR Transaction, when distributions related to the general partner interest and IDRs were made, earnings equal to the amount of distributions were allocated to the general partner before the remaining earnings were allocated to the limited partner unitholders based on their respective ownership percentages. Subsequent to the EQM IDR Transaction, no earnings are allocated to the general partner. The allocation of net income attributable to EQM for purposes of calculating net income per limited partner unit is described in Note 12 . On March 13, 2019, EQM entered into a Convertible Preferred Unit Purchase Agreement (inclusive of certain Joinder Agreements entered into on March 18, 2019, the Preferred Unit Purchase Agreement) with certain investors to issue and sell in a private placement (the Private Placement) an aggregate of 24,605,291 Series A Perpetual Convertible Preferred Units (Series A Preferred Units) representing limited partner interests in EQM for a cash purchase price of $48.77 per Series A Preferred Unit, resulting in total gross proceeds of approximately $1.2 billion . The net proceeds from the Private Placement were used in part to fund the purchase price in the Bolt-on Acquisition (defined in Note 2 ) and to pay certain fees and expenses related to the Bolt-on Acquisition, and the remainder was used for general partnership purposes. The Private Placement closed concurrently with the closing of the Bolt-on Acquisition on April 10, 2019 . See Note 5 for further information on the Series A Preferred Units and the Bolt-on Acquisition. Following the EQM IDR Transaction and the closing of the Private Placement, and as of September 30, 2019 , Equitrans Midstream held a 53.5% limited partner interest (after taking into account the Series A Preferred Units issued in the Private Placement on an as-converted basis) and the non-economic general partner interest in EQM. See Note 5 for further information on the EQM IDR Transaction and Private Placement. Basis of Presentation EQM's consolidated financial statements have been retrospectively recast to include the pre-acquisition results of the Drop-Down Transaction and the EQM-RMP Merger because these transactions represented business combinations between entities under common control. The recast is for the period the acquired businesses were under the common control of EQT, which began on November 13, 2017 as a result of EQT's acquisition of Rice Energy Inc. (Rice) (the Rice Merger). EQM recorded the assets and liabilities acquired in the Drop-Down Transaction and the EQM-RMP Merger at their carrying amounts to EQT on the effective dates of the transactions. The consolidated financial statements are not necessarily indicative of the actual results of operations if EQM and the assets acquired in the Drop-Down Transaction and the EQM-RMP Merger had been operated together during the pre-acquisition periods. Following the completion of the Bolt-on Acquisition, EQM evaluated Eureka Midstream for consolidation and determined that Eureka Midstream does not meet the criteria for variable interest entity classification due to its ability to independently finance its operations through the Eureka Credit Facility (as defined in Note 10 ), as well as each member having proportional voting rights through their equity investments. As such, as of September 30, 2019 , EQM consolidates Eureka Midstream using the voting interest model, recording noncontrolling interest related to the third-party ownership interests in Eureka Midstream. The accompanying unaudited consolidated financial statements have been prepared in accordance with GAAP for interim financial information and with the requirements of Form 10-Q and Article 10 of Regulation S-X. Accordingly, they do not include all of the information and footnotes required by GAAP for complete financial statements. In the opinion of management, these unaudited consolidated financial statements include all adjustments (consisting of only normal, recurring adjustments, unless otherwise disclosed in this Form 10-Q) necessary for a fair presentation of the financial position of EQM as of September 30, 2019 and December 31, 2018 , the results of its operations and equity for the three and nine months ended September 30, 2019 and 2018 , and its cash flows for the nine months ended September 30, 2019 and 2018 . The balance sheet at December 31, 2018 has been derived from the audited financial statements at that date but does not include all of the information and notes required by GAAP for complete financial statements. Due to the seasonal nature of EQM's utility customer contracts, the interim statements for the three and nine months ended September 30, 2019 are not necessarily indicative of the results that may be expected for the year ending December 31, 2019 . EQM and its subsidiaries, including Eureka Midstream, do not have any employees. Operational, management and other services for EQM and its subsidiaries are provided by the directors and officers of the New EQM General Partner and employees of Equitrans Midstream. For further information, refer to the consolidated financial statements and related notes for the year ended December 31, 2018, as well as "Management's Discussion and Analysis of Financial Condition and Results of Operations" contained herein. Recently Issued Accounting Standards In February 2016, the FASB issued ASU 2016-02, Leases . The standard requires entities to record assets and obligations for contracts currently recognized as operating leases. In July 2018, the FASB issued ASU 2018-11, Leases (Topic 842): Targeted Improvements . The update provides an optional transition method of adoption that permits entities to initially apply the standard at the adoption date and recognize a cumulative-effect adjustment to the opening balance of retained earnings in the period of adoption. Under the optional transition method, comparative financial information and disclosures are not required. The update also provides transition practical expedients. The standard requires disclosures of the nature, maturity and value of an entity's lease liabilities and elections taken by the entity. In March 2019, the FASB issued ASU 2019-01, Leases (Topic 842): Codification Improvements , which, among other things, clarifies interim disclosure requirements in the year of ASU 2016-02 adoption. EQM adopted ASU 2016-02, ASU 2018-11 and ASU 2019-01 on January 1, 2019 using the optional transition method. EQM uses a lease accounting system to monitor its current population of lease contracts. EQM implemented processes and controls to review new lease contracts for appropriate accounting treatment in the context of the standards and to generate disclosures required under the standards. For the disclosures required by the standards, see Note 4 . In June 2016, the FASB issued ASU 2016-13, Financial Instruments-Credit Losses: Measurement of Credit Losses on Financial Instruments. The standard amends guidance on reporting credit losses for assets held at amortized cost basis and available for sale debt securities. For assets held at amortized cost basis, this standard eliminates the probable initial recognition threshold in current GAAP, and, in its place, requires an entity to recognize its current estimate of all expected credit losses. The amendments affect loans, debt securities, trade receivables, net investments in leases, off balance sheet credit exposures, reinsurance receivables, and any other financial assets not excluded from the scope of the standard that have the contractual right to receive cash. The standard will be effective for annual reporting periods beginning after December 15, 2019, including interim periods within that reporting period. EQM is currently evaluating the effect this standard will have on its financial statements and related disclosures. In August 2018, the FASB issued ASU 2018-13, Fair Value Measurement, Changes to the Disclosure Requirements for Fair Value Measurement , which makes a number of changes to the hierarchy associated with Level 1, 2 and 3 fair value measurements and the related disclosure requirements. This guidance is effective for fiscal years beginning after December 15, 2019, including interim periods within those fiscal years. Early adoption is permitted. EQM is currently evaluating the effect this standard will have on its financial statements and related disclosures but does not expect the adoption of this standard to have a material effect on its financial statements and related disclosures. In August 2018, the FASB issued ASU 2018-15, Intangibles—Goodwill and Other: Internal-Use Software , which aligns the requirements for capitalizing implementation costs incurred in a hosting arrangement that is a service contract with the requirements for capitalizing implementation costs incurred to develop or obtain internal-use software (and hosting arrangements that include an internal-use software license). This guidance is effective for fiscal years beginning after December 15, 2019, including interim periods within those fiscal years. EQM early-adopted the standard using the prospective method of adoption on January 1, 2019. Following the adoption of ASU 2018-15, EQM began capitalizing certain implementation costs related to cloud computing arrangements that are service contracts. The capitalized portion of these costs are included in the property, plant and equipment line on the consolidated balance sheets and will be amortized over the term of EQM's hosting arrangement. For the three and nine months ended September 30, 2019 , EQM did no t recognize any amortization expense related to implementation costs on its cloud computing arrangements as such assets were not in use. The costs will be included in the selling, general and administrative expense line on the accompanying statements of consolidated operations when recognized. In August 2018, the SEC adopted a final rule under SEC Release No. 33-10532, Disclosure Update and Simplification

Acquisitions, Mergers and Dives

Acquisitions, Mergers and Divestitures	9 Months Ended
	Sep. 30, 2019
Business Combinations [Abstract]
Acquisitions, Mergers and Divestitures	Acquisitions, Mergers and Divestitures Bolt-on Acquisition On March 13, 2019, EQM entered into a Purchase and Sale Agreement (the Purchase and Sale Agreement) with North Haven Infrastructure Partners II Buffalo Holdings, LLC (NHIP), an affiliate of Morgan Stanley Infrastructure Partners, pursuant to which EQM acquired from NHIP a 60% Class A interest in Eureka Midstream Holdings, LLC (Eureka Midstream) and a 100% interest in Hornet Midstream Holdings, LLC (Hornet Midstream) (collectively, the Bolt-on Acquisition) for total consideration of approximately $1.04 billion , composed of approximately $852 million in cash, net of purchase price adjustments, and approximately $192 million in assumed pro-rata debt. Eureka Midstream owns a 190 -mile gathering header pipeline system in Ohio and West Virginia that services both dry Utica and wet Marcellus Shale production. Hornet Midstream owns a 15 -mile, high-pressure gathering system in West Virginia that connects to the Eureka Midstream system. The Bolt-on Acquisition closed on April 10, 2019 and was funded through proceeds from the Private Placement of Series A Preferred Units that closed concurrently with the Bolt-on Acquisition. See Notes 1 and 5 for further information regarding the Private Placement. On the closing of the Bolt-on Acquisition, a subsidiary of Hornet Midstream terminated all of its obligations under its term loan credit agreement and repaid the $28.2 million outstanding principal balance and $0.1 million in related interest and fees. EQM recorded $0.3 million and $17.0 million in acquisition-related expenses related to the Bolt-on Acquisition during the three and nine months ended September 30, 2019 , respectively. The Bolt-on Acquisition acquisition-related expenses included $0.3 million for professional fees for the three months ended September 30, 2019 and $15.3 million for professional fees and $1.7 million for compensation arrangements for the nine months ended September 30, 2019 and are included in separation and other transaction costs in the statements of consolidated operations. Allocation of Purchase Price. The Bolt-on Acquisition was accounted for as a business combination using the acquisition method. The following table summarizes the preliminary purchase price and preliminary estimated fair values of assets acquired and liabilities assumed as of April 10, 2019, with any excess of purchase price over estimated fair value of the identified net assets acquired recorded as goodwill. The $99.7 million of goodwill was allocated to the Gathering segment. Such goodwill primarily relates to additional commercial opportunities, a diversified producer customer mix, increased exposure to dry Utica and wet Marcellus acreage and operating leverage within the Gathering segment. The purchase price allocation and related adjustments remain subject to further adjustments during the applicable measurement period; thus, the purchase price allocation and related adjustments included in the financial statements are preliminary as of September 30, 2019 . The following table summarizes the allocation of the fair value of the assets acquired and liabilities assumed in the Bolt-on Acquisition as of April 10, 2019 by EQM, as well as certain measurement period adjustments made subsequent to EQM's initial valuation. (in thousands) Preliminary Purchase Price Allocation (As initially reported) Measurement Period Adjustments (a) Preliminary Purchase Price Allocation (As adjusted) Consideration given: Cash consideration (b) $ 861,250 $ (11,404 ) $ 849,846 Buyout of Eureka Midstream Class B Units and incentive compensation 2,530 — 2,530 Total consideration 863,780 (11,404 ) 852,376 Fair value of liabilities assumed: Current liabilities 52,458 (9,857 ) 42,601 Long-term debt 300,825 — 300,825 Other long-term liabilities 10,203 — 10,203 Amount attributable to liabilities assumed 363,486 (9,857 ) 353,629 Fair value of assets acquired: Cash 15,145 — 15,145 Accounts receivable 16,817 — 16,817 Inventory 12,991 (26 ) 12,965 Other current assets 882 — 882 Net property, plant and equipment 1,222,284 (8,906 ) 1,213,378 Intangible assets (c) 317,000 (6,000 ) 311,000 Other assets 14,567 — 14,567 Amount attributable to assets acquired 1,599,686 (14,932 ) 1,584,754 Noncontrolling interests (486,062 ) 7,602 (478,460 ) Goodwill as of April 10, 2019 $ 113,642 $ (13,931 ) $ 99,711 Impairment of goodwill (d) (99,711 ) Goodwill as of September 30, 2019 $ — (a) EQM recorded measurement period adjustments to its preliminary acquisition date fair values due to the refinement of its valuation models, assumptions and inputs. The measurement period adjustments were based upon information obtained about facts and circumstances that existed at the acquisition date that, if known, would have affected the measurement of the amounts recognized at that date. (b) The cash consideration for the Bolt-on Acquisition was adjusted by approximately $11.4 million related to working capital adjustments and the release of all escrowed indemnification funds to EQM. (c) After considering the refinements to the valuation models, EQM estimated the fair value of the customer-related intangible assets acquired as part of the Bolt-on Acquisition to be $311.0 million. As a result, the fair value of the customer-related intangible assets was decreased by $6.0 million on September 30, 2019 with a corresponding increase to goodwill. In addition, the change to the provisional amount resulted in a decrease in amortization expense and accumulated amortization of approximately $0.4 million. (d) During the third quarter of 2019, EQM identified impairment indicators that suggested the fair value of its goodwill was more likely than not below its carrying amount. As such, EQM performed an interim goodwill impairment assessment, which resulted in EQM recognizing impairment to goodwill of approximately $261.3 million, of which $99.7 million was associated with its Eureka/Hornet reporting unit bringing the reporting unit's goodwill balance to zero. See Note 3 for further detail. The goodwill impairment charge related to the Eureka/Hornet reporting unit recorded in the third quarter of fiscal 2019 is subject to change based upon the final purchase price allocation during the measurement period for estimated fair values of assets acquired and liabilities assumed in the Bolt-on Acquisition. There can be no assurance that such final allocations will not result in material increases or decreases to the recorded goodwill impairment charge based upon the preliminary purchase price allocations due to changes in the provisional opening balance sheet estimates of goodwill. EQM’s estimates and assumptions are subject to change during the measurement period (up to one year from the acquisition date). The estimated fair value of midstream facilities and equipment, generally consisting of pipeline systems and compression stations, was estimated using the cost approach. Significant unobservable inputs in the estimate of fair value include management's assumptions about the replacement costs for similar assets, the relative age of the acquired assets and any potential economic or functional obsolescence associated with the acquired assets. As a result, the estimated fair value of the midstream facilities and equipment represent a Level 3 fair value measurement. The noncontrolling interest in Eureka Midstream is estimated to be $478 million . The fair value of the noncontrolling interest was calculated based on the enterprise value of Eureka Midstream and the percentage ownership not acquired by EQM. Significant unobservable inputs in the enterprise value of Eureka Midstream include future revenue estimates and future cost assumptions. As a result, the fair value measurement is based on significant inputs that are not observable in the market and thus represents a Level 3 fair value measurement. As part of the preliminary purchase price allocation, EQM identified intangible assets for customer relationships with third-party customers. The fair value of the customer relationships with third-party customers was determined using the income approach, which requires a forecast of the expected future cash flows generated and an estimated market-based weighted average cost of capital. Significant unobservable inputs in the determination of fair value include future revenue estimates, future cost assumptions and estimated customer retention rates. As a result, the estimated fair value of the identified intangible assets represents a Level 3 fair value measurement. EQM calculates amortization of intangible assets using the straight-line method over the estimated useful life of the intangible assets which is 20 years for the Eureka-related intangible assets. As discussed in Note 3 , during the third quarter of 2019 , as a result of the recoverability test, EQM estimated the fair value of the Hornet-related intangible assets and determined that the fair value was not in excess of the assets’ carrying value, which resulted in an impairment charge of approximately $36.4 million related to certain of such intangible assets within EQM's Gathering segment. As a result of the reduction in expected future cash flows, the useful life of the Hornet-related intangible assets was prospectively changed to 7.25 years as of October 1, 2019 , over which EQM calculates amortization using the straight-line method. After the impact of the impairment and the decrease in the useful life of the Hornet-related intangible assets, the expected annual amortization expense increased by $1.0 million . Amortization expense recorded in the statements of consolidated operations for the three and nine months ended September 30, 2019 was $4.1 million and $7.5 million , respectively. The estimated annual amortization expense for the fourth quarter of 2019 and over the successive five years is as follows: 2019 $4.2 million , 2020 $16.8 million , 2021 $16.8 million , 2022 $16.8 million , 2023 $16.8 million and 2024 $16.8 million . Intangible assets, net as of September 30, 2019 , are detailed below. (in thousands) As of September 30, 2019 Intangible assets $ 311,000 Less: impairment of Hornet-related intangible assets (a) 36,405 Less: accumulated amortization 7,517 Intangible assets, net $ 267,078 (a) See Note 3 for disclosure regarding impairments of long-lived assets. Post-Acquisition Operating Results. Subsequent to the completion of the Bolt-on Acquisition, Eureka Midstream and Hornet Midstream collectively contributed the following to both the Gathering segment and EQM's consolidated operating results for the period from April 10, 2019 through September 30, 2019 . (in thousands) (unaudited) April 10, 2019 through September 30, 2019 Operating revenues $ 61,579 Operating loss attributable to EQM $ (109,277 ) Net loss attributable to noncontrolling interests $ (25,664 ) Net loss attributable to EQM $ (87,949 ) Unaudited Pro Forma Information. The following unaudited pro forma combined financial information presents EQM's results as though the EQM IDR Transaction and Bolt-on Acquisition had been completed at January 1, 2018. The pro forma combined financial information has been included for comparative purposes and is not necessarily indicative of the results that might have actually occurred had the EQM IDR Transaction and Bolt-on Acquisition taken place on January 1, 2018; furthermore, the financial information is not intended to be a projection of future results. (in thousands, except per unit data)(unaudited) Nine Months Ended September 30, 2019 Pro forma operating revenues $ 1,235,963 Pro forma net income $ 396,339 Pro forma net loss attributable to noncontrolling interests $ (22,447 ) Pro forma net income attributable to EQM $ 418,786 Pro forma income per limited partner common unit (basic) $ 1.85 Pro forma income per limited partner common unit (diluted) $ 1.78 (in thousands, except per unit data)(unaudited) Three Months Ended September 30, 2018 Nine Months Ended September 30, 2018 Pro forma operating revenues $ 391,151 $ 1,195,096 Pro forma net income $ 221,037 $ 730,440 Pro forma net income attributable to noncontrolling interests $ 4,752 $ 13,462 Pro forma net income attributable to EQM $ 216,285 $ 716,978 Pro forma income per unit (basic) $ 0.95 $ 3.20 Pro forma income per unit (diluted) $ 0.92 $ 3.09 Shared Assets Transaction On March 31, 2019, EQM entered into an Assignment and Bill of Sale (the Assignment and Bill of Sale) with Equitrans Midstream pursuant to which EQM acquired certain assets and assumed certain leases that primarily support EQM’s operations for an aggregate cash purchase price of $49.7 million (the initial purchase price), which reflected the net book value of in-service assets and expenditures made for assets not yet in-service (collectively, and inclusive of the additional assets subsequently acquired as described in the following sentences, the Shared Assets Transaction). Further, pursuant to the Assignment and Bill of Sale, EQM acquired, effective on the first day of the second quarter of 2019, certain additional assets from Equitrans Midstream for $8.9 million cash consideration, reflecting the net book value of in-service assets and expenditures made in respect of assets not yet in-service as of June 30, 2019, which subsequent purchase price was subject to certain adjustments. Additionally, pursuant to the Assignment and Bill of Sale, EQM acquired, effective on the first day of the third quarter of 2019, an additional asset from Equitrans Midstream for a de minimus dollar amount reflecting the net book value of such asset as of September 30, 2019. EQM may, pursuant to the Assignment and Bill of Sale, acquire certain additional assets from Equitrans Midstream for additional cash consideration reflecting the net book value of in-service assets and expenditures made with respect to assets not yet in-service and/or may assume an additional facilities lease. The initial and subsequent purchase prices were funded utilizing EQM’s $3 Billion Facility (defined in Note 10 ). Prior to the Shared Assets Transaction, EQM made quarterly payments to Equitrans Midstream based on fees allocated from Equitrans Midstream for use of in-service assets transferred to EQM in the Shared Assets Transaction. In connection with the entry into the Assignment and Bill of Sale, that certain omnibus agreement (ETRN Omnibus Agreement) among Equitrans Midstream, EQM and the New EQM General Partner (as successor to the Former EQM General Partner) was amended and restated in order to, among other things, govern Equitrans Midstream’s use of the acquired assets following their conveyance to EQM and provide for reimbursement of EQM by Equitrans Midstream for expenses incurred by EQM in connection with such use. EQM-RMP Merger On April 25, 2018, EQM entered into an Agreement and Plan of Merger (the Merger Agreement) with RMP, Rice Midstream Management LLC, the general partner of RMP (the RMP General Partner), the Former EQM General Partner, EQM Acquisition Sub, LLC, a wholly-owned subsidiary of EQM (Merger Sub), EQM GP Acquisition Sub, LLC, a wholly-owned subsidiary of EQM (GP Merger Sub), and, solely for certain limited purposes set forth therein, EQT. Pursuant to the Merger Agreement, on July 23, 2018, Merger Sub and GP Merger Sub merged with and into RMP and the RMP General Partner, respectively, with RMP and the RMP General Partner surviving as wholly-owned subsidiaries of EQM. Pursuant to the Merger Agreement, each RMP common unit issued and outstanding immediately prior to the effective time of the EQM-RMP Merger was converted into the right to receive 0.3319 EQM common units (the Merger Consideration), the issued and outstanding IDRs of RMP were canceled and each outstanding award of phantom units in respect of RMP common units fully vested and converted into the right to receive the Merger Consideration, less applicable tax withholding, in respect of each RMP common unit subject thereto. The aggregate Merger Consideration consisted of 33,975,777 EQM common units of which 9,544,530 EQM common units were received by an indirect wholly-owned subsidiary of EQT. As a result of the EQM-RMP Merger , RMP's common units are no longer publicly traded. Drop-Down Transaction On April 25, 2018, EQT, Rice Midstream Holdings LLC (Rice Midstream Holdings), a wholly-owned subsidiary of EQT, EQM and EQM Gathering Holdings, LLC (EQM Gathering), a wholly-owned subsidiary of EQM, entered into a Contribution and Sale Agreement pursuant to which EQM Gathering acquired from EQT all of EQT's interests in EQM Olympus, Strike Force and EQM WV in exchange for an aggregate of 5,889,282 EQM common units and aggregate cash consideration of approximately $1.15 billion . EQM Olympus owns a natural gas gathering system that gathers gas from wells located primarily in Belmont County, Ohio. Strike Force owns a 75% limited liability company interest in Strike Force Midstream LLC (Strike Force Midstream), which gathers gas from wells located primarily in Belmont and Monroe Counties, Ohio. The Drop-Down Transaction closed on May 22, 2018 with an effective date of May 1, 2018 . As a result of the recast associated with the EQM-RMP Merger and the Drop-Down Transaction, EQM recognized approximately $1,384.9 million of goodwill, all of which was allocated to two reporting units within the Gathering segment. The goodwill value was based on a valuation performed by EQT as of November 13, 2017 with regard to the Rice Merger. EQT recorded goodwill as the excess of the estimated enterprise value of RMP, EQM Olympus, Strike Force and EQM WV over the sum of the fair value amounts allocated to the assets and liabilities of RMP, EQM Olympus, Strike Force and EQM WV. Goodwill was attributed to additional perceived growth opportunities, synergies and operating leverage within the Gathering segment. Prior to the recast, EQM had no goodwill. The following table summarizes the allocation of the fair value of the assets and liabilities of RMP, EQM Olympus, Strike Force and EQM WV as of November 13, 2017 through pushdown accounting from EQT, as well as certain measurement period adjustments made subsequent to EQT's initial valuation. Goodwill and Purchase Price Allocation (Thousands) Estimated fair value of RMP, EQM Olympus, Strike Force (a) and EQM WV $ 4,014,984 Estimated Fair Value of Assets Acquired and Liabilities Assumed: Current assets (b) 132,459 Intangible assets (c) 623,200 Property and equipment, net (d) 2,265,900 Other non-current assets 118 Current liabilities (b) (117,124 ) RMP $850 Million Facility (e) (266,000 ) Other non-current liabilities (e) (9,323 ) Total estimated fair value of assets acquired and liabilities assumed 2,629,230 Goodwill as of November 13, 2017 (f) 1,385,754 Impairment of goodwill (g) 261,941 Goodwill as of December 31, 2018 1,123,813 Impairment of goodwill (h) 161,595 Goodwill as of September 30, 2019 $ 962,218 (a) Includes the estimated fair value attributable to noncontrolling interest in Strike Force of $166 million. (b) The fair value of current assets and current liabilities was assumed to approximate their carrying values. (c) The identifiable intangible assets for customer relationships were estimated by applying a discounted cash flow approach which was adjusted for customer attrition assumptions and projected market conditions. (d) The estimated fair value of long-lived property and equipment were determined utilizing estimated replacement cost adjusted for a usage or obsolescence factor. (e) The estimated fair value of long-term liabilities was determined utilizing observable market inputs where available or estimated based on their then current carrying values. (f) Reflected the value of perceived growth opportunities, synergies and operating leverage anticipated through the acquisitions and ownership of the acquired gathering assets as of November 13, 2017. (g) During its annual goodwill assessment for the year ended December 31, 2018, EQM determined that the carrying value of the RMP PA Gas Gathering (as defined in Note 3) reporting unit, which comprises the Pennsylvania gathering assets acquired in the Rice Merger, was greater than its fair value. As a result, EQM recognized an impairment to goodwill of approximately $261.9 million. (h) As discussed above, during the third quarter of 2019, EQM identified impairment indicators that suggested the fair value of its goodwill was more likely than not below its carrying amount. As such, EQM performed an interim goodwill impairment assessment, which resulted in EQM recognizing an impairment to goodwill of approximately $261.3 million, of which $161.6 million was associated with its RMP PA Gas Gathering reporting unit. As of September 30, 2019, EQM’s goodwill balance was reduced to $962.2 million, including $923.4 million and $38.8 million associated with RMP PA Gas Gathering and Rice Retained Midstream (as defined in Note 3), respectively. See Note 3 for further detail. The Gulfport Transaction On May 1, 2018, pursuant to the Purchase and Sale Agreement, dated April 25, 2018, by and among EQM, EQM Gathering, Gulfport Energy Corporation (Gulfport) and an affiliate of Gulfport, EQM Gathering acquired the remaining 25% limited liability company interest in Strike Force Midstream not then owned by Strike Force for $175 million (the Gulfport Transaction). As a result, EQM owned 100% of Strike Force Midstream effective as of May 1, 2018. RMP and the entities part of the Drop-Down Transaction were businesses and the related acquisitions were transactions between entities under common control; therefore, EQM recorded the assets and liabilities of these entities at their carrying amounts to EQT on the date of the respective transactions. The difference between EQT's net carrying amount and the total consideration paid to EQT was recorded as a capital transaction with EQT, which resulted in a reduction in equity. This portion of the consideration was recorded in financing activities in the statements of consolidated cash flows. EQM recast its consolidated financial statements to retrospectively reflect the EQM-RMP Merger and the Drop-Down Transaction for the periods the acquired businesses were under the common control of EQT; however, the consolidated financial statements are not necessarily indicative of the results of operations that would have occurred if EQM had owned the acquired businesses during the periods reported. Divestitures As discussed in Note 3 , EQM incurred an $80.1 million impairment charge during the second quarter of 2019 associated with certain FERC-regulated low-pressure gathering pipelines. During the third quarter of 2019, EQM divested certain of its FERC-regulated low-pressure gathering pipelines associated with its Copley gathering system located in West Virginia. On August 14, 2019 , Equitrans, L.P., a subsidiary of EQM, entered into a Purchase and Sale Agreement with Diversified Gas & Oil Corporation for the sale of the Copley gathering system (including approximately 530 miles of low-pressure gathering pipelines, four compressor stations and related assets) for a purchase price of $1,000 , subject to certain post-closing adjustments and FERC approval. The initial transaction closed on September 26, 2019 in respect of non-certificated gathering assets comprising a portion of the Copley gathering system. The second transaction will be completed following FERC approval of the abandonment of the certificated assets, which is expected in the fourth quarter of 2019.

Impairments of Long-Lived Asset

Impairments of Long-Lived Assets	9 Months Ended
	Sep. 30, 2019
Property, Plant and Equipment [Abstract]
Impairments of Long-Lived Assets	Impairments of Long-Lived Assets Impairment of goodwill Goodwill is evaluated for impairment at least annually and whenever events or changes in circumstance indicate that the fair value of a reporting unit is less than its carrying amount. EQM may perform either a qualitative assessment of potential impairment or proceed directly to a quantitative assessment of potential impairment. EQM's qualitative assessment of potential impairment may result in the determination that a quantitative impairment analysis is not necessary. Under this elective process, EQM assesses qualitative factors to determine whether the existence of events or circumstances leads EQM to determine that it is more likely than not that the fair value of a reporting unit is less than its carrying amount. If after assessing the totality of events or circumstances, EQM determines it is more likely than not that the fair value of a reporting unit is greater than its carrying amount, then a quantitative assessment is not required. However, if EQM concludes otherwise, a quantitative impairment analysis is performed. If EQM chooses not to perform a qualitative assessment, or if it chooses to perform a qualitative assessment but is unable to qualitatively conclude that no impairment has occurred, then EQM will perform a quantitative assessment. In the case of a quantitative assessment, EQM estimates the fair value of the reporting unit with which the goodwill is associated and compares it to the carrying value. If the estimated fair value of a reporting unit is less than its carrying value, an impairment charge is recognized for the excess of the reporting unit's carrying value over its fair value. The three reporting units to which EQM's goodwill is recorded are (i) the Ohio gathering assets acquired in the Rice Merger (Rice Retained Midstream), (ii) the Pennsylvania gathering assets acquired in the Rice Merger (RMP PA Gas Gathering) and (iii) the Ohio and West Virginia gathering assets acquired in the Bolt-on Acquisition (Eureka/Hornet, collectively with Rice Retained Midstream and RMP PA Gas Gathering, the Reporting Units). The Reporting Units earn a substantial portion of their revenues from volumetric-based fees, which are sensitive to changes in their customers' development plans. During the third quarter of 2019, EQM identified impairment indicators in the form of significant declines in the unit price of EQM's common units and corresponding market capitalization, primarily as a result of continued suppressed natural gas prices and decreased producer drilling activity. Management considered these price effects and activity declines as indicators that the fair value of goodwill was more likely than not below the Reporting Units' carrying amount. As such, the performance of an interim goodwill impairment assessment was required. In estimating the fair value of the Reporting Units, EQM used a combination of the income approach and the market approach. EQM used the income approach’s discounted cash flow method, which applies significant inputs not observable in the public market (Level 3), including estimates and assumptions related to the use of an appropriate discount rate, future throughput volumes, operating costs, capital spending and changes in working capital. EQM used the market approach’s comparable company method and reference transaction method. The comparable company method evaluates the value of a company using metrics of other businesses of similar size and industry. The reference transaction method evaluates the value of a company based on pricing multiples derived from similar transactions entered into by similar companies. During the third quarter of 2019, EQM determined that the fair value of Rice Retained Midstream was greater than its carrying value; however, the carrying values of RMP PA Gas Gathering and Eureka/Hornet were each greater than their respective fair values. As a result, EQM recognized impairment of goodwill of $161.6 million and $99.7 million on RMP PA Gas Gathering and Eureka/Hornet, respectively. The non-cash impairment charge is included in the impairments of long-lived assets line on EQM's statements of consolidated operations. As of September 30, 2019, EQM’s goodwill balance was reduced to $962.2 million , including $923.4 million and $38.8 million associated with RMP PA Gas Gathering and Rice Retained Midstream, respectively. Impairment of long-lived assets and intangible assets EQM evaluates long-lived assets, including related intangibles, for impairment when events or changes in circumstances indicate, in management's judgment, that the carrying value of such assets may not be recoverable. Asset recoverability is measured by comparing the carrying value of the asset or asset group with its expected future pre-tax undiscounted cash flows. These cash flow estimates require EQM to make projections and assumptions for many years into the future for pricing, demand, competition, operating cost and other factors. If the carrying amount exceeds the expected future undiscounted cash flows, EQM recognizes an impairment equal to the excess of net book value over fair value as determined by quoted market prices in active markets or present value techniques if quotes are unavailable. The determination of the fair value using present value techniques requires EQM to make projections and assumptions regarding the probability of a range of outcomes and the rates of interest used in the present value calculations. Any changes EQM makes to these projections and assumptions could result in significant revisions to its evaluation of recoverability of its property, plant and equipment and the recognition of additional impairments. During the third quarter of 2019, EQM performed a recoverability test due to the triggering events described in the goodwill impairment summary above. As a result of the recoverability test, management determined that the carrying value of certain long-lived assets associated with Eureka/Hornet were not recoverable. The assets deemed not recoverable were customer-related intangible assets associated with Hornet Midstream, an asset group within Eureka/Hornet, that were acquired as part of the Bolt-on Acquisition. EQM estimated the fair value of the Hornet-related intangible assets and determined that the fair value was not in excess of the assets’ carrying value, which resulted in an impairment charge of approximately $36.4 million related to certain of such intangible assets within EQM's Gathering segment. The non-cash impairment charge is included in the impairments of long-lived assets line on the statements of consolidated operations. During the second quarter of 2019, EQM reassessed its asset groupings for its regulated pipelines due to certain regulatory ratemaking policy changes affecting the regulated pipelines, changes in strategic focus and plans for segmentation of operations. Prior to the second quarter of 2019, EQM defined its regulated asset grouping to include the FERC-regulated transmission and storage assets, integrated with the low-pressure assets due to overlapping operations, shared costs structure and similar ratemaking structures. During the second quarter, EQM reached a settlement related to its FERC Form 501-G report, which was focused solely on EQM’s FERC-regulated transmission and storage assets. The settlement further differentiated the rate structures, which are primarily negotiated rates for the FERC-regulated transmission assets versus the tariff-based rate structure for the FERC-regulated low-pressure gathering assets. Further, management increased its operational focus and emphasis on high-pressure gathering assets as illustrated by the consummation of the Bolt-on Acquisition. As a result of these regulatory changes and shift in operational focus, beginning with the second quarter of 2019, EQM groups its FERC-regulated assets in two asset groupings: FERC-regulated transmission and storage assets and FERC-regulated low-pressure gathering assets. Upon the change in asset grouping, management evaluated whether any indicators of impairment were present and in conjunction with the evaluation, EQM determined that the carrying values for the non-core FERC-regulated low-pressure gathering assets exceeded their undiscounted cash flows. Additionally, following the settlement related to the FERC Form 501-G report, management does not currently plan to seek to recover the deficient cash flows through a future rate proceeding. EQM therefore estimated the fair values of FERC-related low-pressure gathering assets and determined that their fair values were not in excess of the assets’ carrying values, which resulted in recognized impairments of property and equipment of approximately $80.1 million related to the assets within EQM's Gathering segment. As a result of the impairment, the assets carry no book value. The non-cash impairment charge is included in the impairments of long-lived assets line on EQM's statements of consolidated operations for the nine months ended September 30, 2019 . See Note 2

Leases

Leases	9 Months Ended
	Sep. 30, 2019
Leases [Abstract]
Leases	Leases As discussed in Note 1 , EQM adopted ASU 2016-02, ASU 2018-11 and ASU 2019-01 on January 1, 2019 (the Adoption Date) using the optional transition method of adoption. EQM elected a package of practical expedients that allows an entity to not reassess (i) whether a contract is or contains a lease, (ii) lease classification and (iii) initial direct costs. In addition, EQM elected the following practical expedients: (i) to not reassess certain land easements, (ii) to not apply the recognition requirements under the standard to short-term leases and (iii) to combine and account for lease and nonlease contract components as a lease, which requires the capitalization of fixed nonlease payments on the Adoption Date or lease effective date and the recognition of variable nonlease payments as variable lease expense. Nonlease payments include payments for property taxes and other operating and maintenance expenses incurred by the lessor but payable by EQM in connection with the leasing arrangement. On the Adoption Date, EQM recorded on its consolidated balance sheets an operating lease right-of-use asset and a corresponding operating lease liability of $2.3 million , reflecting the present value of future lease payments on EQM's facility and compressor lease contracts. The discount rate used to determine present value, referred to as the incremental borrowing rate, was based on the rate of interest that EQM estimated it would have to pay to borrow (on a collateralized-basis over a similar term) an amount equal to the lease payments in a similar economic environment as of the Adoption Date. EQM is required to reassess the incremental borrowing rate for any new and modified lease contracts as of the contract effective date. Adoption of the standard did not require an adjustment to the opening balance of retained earnings. As of the Adoption Date and September 30, 2019 , EQM had no lease contracts classified as financing leases and was neither a lessor nor party to a subleasing arrangement. In connection with the Shared Assets Transaction discussed in Note 2 , on March 31, 2019, Equitrans Midstream assigned to EQM two lease agreements that support EQM operations (the Shared Leases Assignment), one of which provides rights to a facility and the other to a compressor station. As a result of the Shared Leases Assignment, EQM recorded $33.0 million of right-of-use assets and corresponding operating lease liabilities. In addition, in connection with the Bolt-on Acquisition discussed in Note 2 , EQM acquired 10 compressor leases and one facilities lease for which it recorded approximately $1.7 million and $3.0 million in operating lease expenses during the three and nine months ended September 30, 2019 , respectively. EQM recorded operating lease right-of-use assets and a corresponding operating lease liability of approximately $20.0 million for these acquired leases. The following table summarizes operating lease cost for the three and nine months ended September 30, 2019 . Three Months Ended September 30, 2019 Nine Months Ended (Thousands) Operating lease cost $ 2,838 $ 6,987 Short-term lease cost 1,473 3,353 Variable lease cost 100 112 Total lease cost $ 4,411 $ 10,452 Operating lease expense related to EQM's compressor lease contracts and facility lease contracts is reported in operating and maintenance expense and selling, general and administrative expense, respectively, on EQM's statements of consolidated operations. For the three and nine months ended September 30, 2019 , cash paid for operating lease liabilities was $2.5 million and $6.3 million , respectively, which was reported in cash flows provided by operating activities on EQM's statements of consolidated cash flows. The operating lease right-of-use assets are reported in other assets and the current and noncurrent portions of the operating lease liabilities are reported in accrued liabilities and regulatory and other long-term liabilities, respectively, on the consolidated balance sheets. As of September 30, 2019 , the operating lease right-of-use assets were $52.4 million and operating lease liabilities were $53.4 million , of which $10.1 million was classified as current. As of September 30, 2019 , the weighted average remaining lease term was 8 years and the weighted average discount rate was 5.4% . Schedule of Operating Lease Liability Maturities. The following table summarizes undiscounted cash flows owed by EQM to lessors pursuant to contractual agreements in effect as of September 30, 2019 and related imputed interest. The majority of EQM's lease agreements have multiple renewal periods at EQM's option; however, because none of the renewal periods are reasonably assured to be exercised, the associated operating lease payments have not been included in the table below. September 30, 2019 (Thousands) 2019 $ 3,218 2020 12,168 2021 9,913 2022 7,694 2023 5,607 2024 3,966 Thereafter 24,728 Total 67,294 Less: imputed interest 13,926 Present value of operating lease liability $ 53,368

Equity

Equity	9 Months Ended
	Sep. 30, 2019
Equity [Abstract]
Equity	Equity The following table summarizes changes in EQM's Series A Preferred Units, common units and Class B units, each representing limited partner interests in EQM, and general partner units during the year ended December 31, 2018 and from January 1, 2019 through September 30, 2019 . Limited Partner Interests Series A Preferred Units Common Units Class B Units General Partner Units Total Balance at January 1, 2018 — 80,581,758 — 1,443,015 82,024,773 Common units issued (1) — 10,821 — — 10,821 Drop-Down Transaction consideration — 5,889,282 — — 5,889,282 Common units issued in the EQM-RMP Merger — 33,975,777 — — 33,975,777 Balance at December 31, 2018 — 120,457,638 — 1,443,015 121,900,653 Unit cancellation — (8 ) — — (8 ) EQM IDR Transaction (2) — 80,000,000 7,000,000 (1,443,015 ) 85,556,985 Issuance of Series A Preferred Units 24,605,291 — — — 24,605,291 Balance at September 30, 2019 24,605,291 200,457,630 7,000,000 — 232,062,921 (1) Units issued upon the resignation of a member of the Board of Directors of EQM's general partner. (2) In exchange for the cancellation of the EQM IDRs, EQM issued 87,000,000 EQM common units (the Exchange Consideration) to the Former EQM General Partner. At the effective time of the EQM IDR Merger, (i) the Exchange Consideration held by the Former EQM General Partner was canceled, (ii) 80,000,000 EQM common units and 7,000,000 Class B units were issued on a pro rata basis to certain affiliates of Equitrans Midstream, and (iii) 21,811,643 EQM common units held by EQGP were canceled and 21,811,643 EQM common units were issued pro rata to certain affiliates of Equitrans Midstream. As of September 30, 2019 , Equitrans Gathering Holdings, LLC (Equitrans Gathering Holdings), EQM GP Corporation (EQM GP Corp) and Equitrans Midstream Holdings, LLC (EMH), each a wholly-owned subsidiary of Equitrans Midstream, held 89,505,616 , 89,536 and 27,650,303 EQM common units, respectively. Additionally, Equitrans Gathering Holdings, EQM GP Corp and EMH held 6,153,907 , 6,155 and 839,938 Class B units, respectively. As of September 30, 2019 , Equitrans Midstream owned, directly or indirectly, 117,245,455 EQM common units and 7,000,000 Class B units (collectively representing, after taking into account the Series A Preferred Units issued in the Private Placement on an as-converted basis, a 53.5% limited partner interest in EQM) and the entire non-economic general partner interest in EQM, while the public owned a 46.5% limited partner interest in EQM. Class B Units As discussed above and in Note 1 , in February 2019, EQM issued 7,000,000 Class B units representing a new class of limited partner interests in EQM as partial consideration for the EQM IDR Transaction. The Class B units are substantially similar in all respects to EQM's common units, except that the Class B units are not entitled to receive distributions of available cash until the applicable Class B unit conversion date (or, if earlier, a change of control). The Class B units are divided into three tranches, with the first tranche of 2,500,000 Class B units becoming convertible at the holder’s option into EQM common units on April 1, 2021, the second tranche of 2,500,000 Class B units becoming convertible at the holder’s option into EQM common units on April 1, 2022, and the third tranche of 2,000,000 Class B units becoming convertible at the holder’s option into EQM common units on April 1, 2023 (each, a Class B unit conversion date). Additionally, the Class B units will become convertible at the holder’s option into EQM common units immediately before a change of control of EQM. After the applicable Class B unit conversion date (or, if earlier, a change of control), whether or not such Class B units have been converted into EQM common units, the Class B units will participate pro rata with the EQM common units in distributions of available cash. The holders of Class B units vote together with the holders of EQM common units as a single class, except that Class B units owned by the general partner of EQM and its affiliates are excluded from voting if EQM common units owned by such parties are excluded from voting. Holders of Class B units are entitled to vote as a separate class on any matter that adversely affects the rights or preferences of the Class B units in relation to other classes of EQM partnership interests in any material respect or as required by law. Series A Preferred Units As discussed in Note 1 , in March 2019, EQM entered into the Preferred Unit Purchase Agreement with certain investors to issue and sell in the Private Placement an aggregate of 24,605,291 Series A Preferred Units representing limited partner interests in EQM for a cash purchase price of $48.77 per Series A Preferred Unit, resulting in total gross proceeds of approximately $1.2 billion . The net proceeds from the Private Placement were used in part to fund the purchase price in the Bolt-on Acquisition and to pay certain fees and expenses related to the Bolt-on Acquisition, and the remainder was used for general partnership purposes. The Private Placement closed concurrently with the closing of the Bolt-on Acquisition on April 10, 2019 . The Series A Preferred Units rank senior to all common units and Class B units representing limited partner interests in EQM with respect to distribution rights and rights upon liquidation. The Series A Preferred Units vote on an as-converted basis with the EQM common units and Class B units and have certain other class voting rights with respect to any amendment to EQM's partnership agreement or its certificate of limited partnership that would be adverse (other than in a de minimis manner) to any of the rights, preferences or privileges of the Series A Preferred Units. The holders of the Series A Preferred Units are entitled to receive cumulative quarterly distributions at a rate of $1.0364 per Series A Preferred Unit for the first twenty distribution periods, and thereafter the quarterly distributions on the Series A Preferred Units will be an amount per Series A Preferred Unit for such quarter equal to (i) the Series A Preferred Unit purchase price of $48.77 per such unit, multiplied by (ii) a percentage equal to the sum of (A) the greater of (x) the 3-month LIBOR as of the second London banking day prior to the beginning of the applicable quarter and (y) 2.59% , and (B) 6.90% , multiplied by (iii) 25% . EQM will not be entitled to pay any distributions on any junior securities, including any EQM common units, prior to paying the quarterly distributions payable to the holders of Series A Preferred Units, including any previously accrued and unpaid distributions. Each holder of the Series A Preferred Units may elect to convert all or any portion of the Series A Preferred Units owned by it into EQM common units initially on a one-for-one basis, subject to customary anti-dilution adjustments and an adjustment for any distributions that have accrued but have not been paid when due and partial period distributions, at any time (but not more often than once per fiscal quarter) after April 10, 2021 (or earlier upon the liquidation, dissolution or winding up of EQM), provided that any conversion is for at least $30 million (calculated based on the closing price of the EQM common units on the trading day preceding notice of conversion) or such lesser amount if such conversion relates to all of a holder’s remaining Series A Preferred Units. EQM may elect to convert all or any portion of the Series A Preferred Units into EQM common units at any time (but not more often than once per quarter) after April 10, 2021 if (i) the common units are listed for, or admitted to, trading on a national securities exchange, (ii) the closing price per common unit on the national securities exchange on which the common units are listed for, or admitted to, trading exceeds 140% of the Series A Preferred Unit purchase price of $48.77 per such unit for the 20 consecutive trading days immediately preceding notice of the conversion, (iii) the average daily trading volume of the common units on the national securities exchange on which the common units are listed for, or admitted to, trading exceeds 500,000 common units for the 20 consecutive trading days immediately preceding notice of the conversion, (iv) EQM has an effective registration statement on file with the SEC covering resales of the common units to be received by such holders upon any such conversion and (v) EQM has paid all accrued quarterly distributions in cash to the holders. In addition, upon certain events involving a change in control, the holders of Series A Preferred Units may elect, among other potential elections, to convert their preferred units into EQM common units at a certain conversion rate. Net Income per Limited Partner Unit and Cash Distributions Net Income per Limited Partner Unit. Net income per limited partner unit is calculated utilizing the two-class method by dividing the limited partner interest in net income by the weighted average number of limited partner units outstanding during the period. The two-class method uses an earnings allocation method under which earnings per limited partner unit are calculated for each class of common unit and any participating security considering all distributions declared and participation rights in undistributed earnings as if all earnings had been distributed during the period. Diluted net income per limited partner unit reflects the potential dilution that could occur if securities or agreements to issue common units were exercised, settled or converted into EQM common units. EQM uses the if-converted method to compute potential common units from phantom units granted to independent and non-employee directors and to compute potential common units related to the conversion of Series A Preferred Units and Class B units. Under the if-converted method, dilutive convertible securities are assumed to be converted from the date of the issuance, and the resulting common units are included in the denominator of the diluted net income per unit calculation for the period being presented. Each series of potential common units is evaluated in sequence from the most dilutive to the least dilutive. Distributions declared in the period and undeclared distributions on the cumulative Series A Preferred Units that accumulated during the period are added back to the numerator for purposes of the if-converted calculation. As a result of the EQM IDR Transaction, EQM’s common unitholders are entitled to all distributions until the Class B units are converted to common units (other than distributions in respect of the Series A Preferred Units). Class B unitholders have no rights to distributions until the Class B units are convertible into common units. Accordingly, for all periods prior to the date such Class B units are convertible, the Class B units are not considered participating securities under the two-class method. In addition, the Series A Preferred Units are not considered a participating security as they only have distribution rights up to the specified per-unit quarterly distribution and have no rights to EQM’s undistributed earnings prior to conversion of the Series A Preferred Units into EQM common units, as discussed in Note 5 . For the three and nine months ended September 30, 2019 , limited partner interest in net income, which excludes the Series A Preferred Units interest in net income, was fully allocated to EQM’s common unitholders. For the three and nine months ended September 30, 2018 , net income attributable to EQM was allocated to the general partner and limited partners in accordance with their respective ownership percentages. Any common units issued during the relevant periods are included on a monthly weighted-average basis for the periods in which they were outstanding. The phantom units granted to the independent and non-employee directors of EQM's general partner will be paid in common units on a director’s termination of service on the Board of Directors of EQM's general partner. The weighted average phantom unit awards included in the calculation of basic weighted average limited partner units outstanding were 25,305 and 17,816 for the three months ended September 30, 2019 and 2018 , respectively, and 23,687 and 19,699 for the nine months ended September 30, 2019 and 2018, respectively. The following table presents EQM's calculation of net income per limited partner unit for common and Class B limited partner units. Three Months Ended Nine Months Ended 2019 2018 (1) 2019 2018 (1) (Thousands, except per unit data) Net (loss) income attributable to EQM $ (10,518 ) $ 209,927 $ 393,851 $ 704,109 Less: Series A Preferred Units interest in net income (25,501 ) — (48,480 ) — Less: pre-acquisition net income allocated to EQT — (8,490 ) — (164,242 ) Less: general partner interest in net income – general partner units — (2,379 ) — (7,145 ) Less: general partner interest in net income – IDRs — (70,967 ) — (183,253 ) Limited partner interest in net (loss) income $ (36,019 ) $ 128,091 $ 345,371 $ 349,469 Net (loss) income allocable to common units $ (36,019 ) $ 128,091 $ 345,371 $ 349,469 Net (loss) income allocable to Class B units $ — $ — $ — $ — Weighted average limited partner common units outstanding - basic 200,483 111,980 185,244 93,746 Weighted average limited partner common units outstanding - diluted (2) 200,483 111,980 192,244 93,746 Net (loss) income per limited partner common unit - basic $ (0.18 ) $ 1.14 $ 1.86 $ 3.73 Net (loss) income per limited partner common unit - diluted $ (0.18 ) $ 1.14 $ 1.80 $ 3.73 (1) Net income attributable to the Drop-Down Transaction and the EQM-RMP Merger for the periods prior to May 1, 2018 and July 23, 2018, respectively, was not allocated to the limited partners for purposes of calculating net income per limited partner unit as these pre-acquisition amounts were not available to the EQM unitholders. (2) In periods when EQM reports a net loss, the Class B and Series A Preferred Units are excluded from the calculation of diluted weighted average units outstanding because of their anti-dilutive effect on loss per unit. For the three months ended September 30, 2019 , 7,000,000 Class B units and 24,605,291 Series A Preferred Units were excluded in the calculation of diluted weighted average limited partner units outstanding as the effect of these units were anti-dilutive. For the nine months ended September 30, 2019 , 7,000,000 Class B units were included in the calculation of diluted weighted average limited partner units outstanding based upon the application of the if-converted method. The effect of Series A Preferred Units was anti-dilutive. Distributions to common unitholders. On October 21, 2019 , the Board of Directors of EQM's general partner declared a cash distribution to EQM's unitholders for the third quarter of 2019 of $1.160 per common unit. The cash distribution will be paid on November 13, 2019 to common unitholders of record at the close of business on November 1, 2019 . Cash distributions paid by EQM to Equitrans Midstream will be approximately $136.0 million related to Equitrans Midstream's limited partner interest in EQM. Distributions to Series A Preferred Unit holders. On October 21, 2019 , the Board of Directors of EQM's general partner declared a quarterly cash distribution on the Series A Preferred Units for the third quarter of 2019 of $1.0364 per Series A Preferred Unit. The cash distribution will be paid on November 13, 2019 to Series A Preferred unitholders of record at the close of business on November 1, 2019 . For the quarter ended September 30, 2019 , no distributions were declared on the Class B units as none of these units were convertible into EQM common units.

Financial Information by Busine

Financial Information by Business Segment	9 Months Ended
	Sep. 30, 2019
Segment Reporting [Abstract]
Financial Information by Business Segment	Financial Information by Business Segment EQM reports its operations in three segments that reflect its three lines of business: Gathering, Transmission and Water. Gathering includes EQM's high-pressure gathering lines and FERC-regulated low-pressure gathering lines; Transmission includes EQM's FERC-regulated interstate pipelines and storage system; and Water consists of EQM's water pipelines, impoundment facilities, pumping stations, take point facilities and measurement facilities. Three Months Ended Nine Months Ended 2019 2018 2019 2018 (Thousands) Revenues from customers: Gathering $ 299,491 $ 252,861 $ 847,038 $ 731,440 Transmission 87,299 89,350 289,926 285,429 Water 21,644 22,373 67,419 93,438 Total operating revenues $ 408,434 $ 364,584 $ 1,204,383 $ 1,110,307 Operating (loss) income: Gathering (a) $ (98,489 ) $ 177,902 $ 177,720 $ 510,755 Transmission 59,690 58,691 207,684 198,784 Water 7,722 (3,093 ) 18,980 35,627 Total operating (loss) income $ (31,077 ) $ 233,500 $ 404,384 $ 745,166 Reconciliation of operating (loss) income to net (loss) income: Equity income (b) $ 44,448 $ 16,087 $ 112,293 $ 35,836 Other income 337 1,345 4,506 3,193 Net interest expense 53,923 41,005 152,996 76,740 Net (loss) income $ (40,215 ) $ 209,927 $ 368,187 $ 707,455 (a) Impairments of long-lived assets of $298.7 million and $378.8 million for the three and nine months ended September 30, 2019, respectively, were included in Gathering operating (loss) income. See Note 3 for further information. (b) Equity income is included in the Transmission segment. September 30, December 31, (Thousands) Segment assets: Gathering $ 7,949,204 $ 6,011,654 Transmission (a) 3,801,905 3,066,659 Water 198,672 237,602 Total operating segments 11,949,781 9,315,915 Headquarters, including cash 204,256 140,206 Total assets $ 12,154,037 $ 9,456,121 (a) The equity investment in the MVP Joint Venture is included in the Transmission segment. Three Months Ended Nine Months Ended 2019 2018 2019 2018 (Thousands) Depreciation: Gathering $ 38,943 $ 25,359 $ 104,502 $ 72,309 Transmission 13,347 12,357 38,474 37,228 Water 6,907 5,851 19,801 17,420 Total $ 59,197 $ 43,567 $ 162,777 $ 126,957 Expenditures for segment assets: Gathering (a)(b) $ 272,138 $ 194,477 $ 745,053 $ 515,072 Transmission (c) 16,296 37,626 46,287 84,517 Water 13,466 7,981 31,490 17,358 Total (d) $ 301,900 $ 240,084 $ 822,830 $ 616,947 (a) Includes approximately $0.3 million and $58.9 million for the three and nine months ended September 30, 2019 , respectively, related to non-operating assets acquired from Equitrans Midstream in the Shared Assets Transaction that primarily support EQM's gathering activities. (b) Includes approximately $6.7 million and $17.6 million of capital expenditures related to noncontrolling interests in Eureka Midstream for the three and nine months ended September 30, 2019 , respectively. (c) Transmission capital expenditures do not include capital contributions made to the MVP Joint Venture for the MVP and MVP Southgate projects of approximately $211.7 million and $263.2 million for the three months ended September 30, 2019 and 2018 , respectively, and approximately $512.9 million and $446.0 million for the nine months ended September 30, 2019 and 2018 , respectively. (d) EQM accrues capital expenditures when the work has been completed but the associated bills have not yet been paid. Accrued capital expenditures are excluded from the statements of consolidated cash flows until they are paid. Accrued capital expenditures were approximately $115.5 million , $110.8 million and $108.9 million at September 30, 2019 , June 30, 2019 and December 31, 2018 , respectively. Accrued capital expenditures were approximately $91.3 million , $84.6 million and $90.7 million at September 30, 2018 , June 30, 2018 and December 31, 2017 , respectively. On April 10, 2019, as a result of the Bolt-on Acquisition, EQM assumed $8.8 million of Eureka Midstream accrued capital expenditures.

Revenue from Contracts with Cus

Revenue from Contracts with Customers	9 Months Ended
	Sep. 30, 2019
Revenue from Contract with Customer [Abstract]
Revenue from Contracts with Customers	Revenue from Contracts with Customers For the three and nine months ended September 30, 2019 and 2018 , all revenues recognized on EQM's statements of consolidated operations are from contracts with customers. As of September 30, 2019 and December 31, 2018 , all receivables recorded on EQM's consolidated balance sheets represent performance obligations that have been satisfied and for which an unconditional right to consideration exists. Summary of Disaggregated Revenues . The tables below provide disaggregated revenue information by business segment. Three Months Ended September 30, 2019 Gathering Transmission Water Total (Thousands) Firm reservation fee revenues $ 154,791 $ 81,990 $ — $ 236,781 Volumetric-based fee revenues 144,700 5,309 — 150,009 Water services revenues — — 21,644 21,644 Total operating revenues $ 299,491 $ 87,299 $ 21,644 $ 408,434 Three Months Ended September 30, 2018 Gathering Transmission Water Total (Thousands) Firm reservation fee revenues $ 112,598 $ 82,669 $ — $ 195,267 Volumetric-based fee revenues 140,263 6,681 — 146,944 Water services revenues — — 22,373 22,373 Total operating revenues $ 252,861 $ 89,350 $ 22,373 $ 364,584 Nine Months Ended September 30, 2019 Gathering Transmission Water Total (Thousands) Firm reservation fee revenues $ 431,520 $ 263,051 $ — $ 694,571 Volumetric-based fee revenues 415,518 26,875 — 442,393 Water services revenues — — 67,419 67,419 Total operating revenues $ 847,038 $ 289,926 $ 67,419 $ 1,204,383 Nine Months Ended September 30, 2018 Gathering Transmission Water Total (Thousands) Firm reservation fee revenues $ 334,233 $ 262,666 $ — $ 596,899 Volumetric-based fee revenues 397,207 22,763 — 419,970 Water services revenues — — 93,438 93,438 Total operating revenues $ 731,440 $ 285,429 $ 93,438 $ 1,110,307 Summary of Remaining Performance Obligations. The following table summarizes the transaction price allocated to EQM's remaining performance obligations under all contracts with firm reservation fees and MVCs as of September 30, 2019 . 2019 (a) 2020 2021 2022 2023 Thereafter Total (Thousands) Gathering firm reservation fees $ 124,735 $ 512,126 $ 586,691 $ 591,430 $ 590,342 $ 2,152,476 $ 4,557,800 Gathering revenues supported by MVCs 41,341 133,969 153,065 153,065 152,242 626,548 1,260,230 Transmission firm reservation fees 92,853 348,324 374,627 370,617 332,393 2,731,561 4,250,375 Total $ 258,929 $ 994,419 $ 1,114,383 $ 1,115,112 $ 1,074,977 $ 5,510,585 $ 10,068,405 (a) October 1, 2019 through December 31, 2019. Based on total projected contractual revenues, including projected contractual revenues from future capacity expected from expansion projects that are not yet fully constructed for which EQM has executed firm contracts, EQM's firm gathering contracts and firm transmission and storage contracts had weighted average remaining terms of approximately 11 years and 14 years, respectively, as of September 30, 2019 .

Related Party Transactions

Related Party Transactions	9 Months Ended
	Sep. 30, 2019
Related Party Transactions [Abstract]
Related Party Transactions	Related Party Transactions Pursuant to the ETRN Omnibus Agreement, Equitrans Midstream performs centralized corporate, general and administrative services for EQM. In exchange, EQM reimburses Equitrans Midstream for the expenses incurred by Equitrans Midstream in providing these services. In connection with the entry into the Assignment and Bill of Sale, the ETRN Omnibus Agreement was amended and restated, to, among other things, govern Equitrans Midstream's use, and payment for such use, of the acquired assets following their conveyance to EQM. Pursuant to a secondment agreement, employees of Equitrans Midstream and its affiliates may be seconded to EQM to provide operating and other services with respect to EQM's business under the direction, supervision and control of EQM. EQM reimburses Equitrans Midstream and its affiliates for the services provided by the seconded employees. The expenses for which EQM reimburses Equitrans Midstream and its affiliates may not necessarily reflect the actual expenses that EQM would incur on a stand-alone basis. EQM is unable to estimate what those expenses would be on a stand-alone basis. Equitrans Midstream is generally responsible for the surviving obligations of EQT under certain omnibus agreements pursuant to the Separation and Distribution Agreement. As of September 30, 2019 , EQT remained a related party following the Separation due to its 19.9% ownership interest in Equitrans Midstream. In the ordinary course of business, EQM engaged, and continues to engage, in transactions with EQT and its affiliates, including, but not limited to and as applicable, gathering agreements, transportation service and precedent agreements, storage agreements and water services agreements.

Investment in Unconsolidated En

Investment in Unconsolidated Entity	9 Months Ended
	Sep. 30, 2019
Equity Method Investments and Joint Ventures [Abstract]
Investment in Unconsolidated Entity	Investment in Unconsolidated Entity The MVP Joint Venture is constructing the Mountain Valley Pipeline (MVP), an estimated 300 -mile natural gas interstate pipeline that will span from northern West Virginia to southern Virginia. EQM is the operator of the MVP and owned a 45.5% interest in the MVP project as of September 30, 2019 . The MVP Joint Venture is a variable interest entity because it has insufficient equity to finance its activities during the construction stage of the project. EQM is not the primary beneficiary of the MVP Joint Venture because it does not have the power to direct the activities that most significantly affect the MVP Joint Venture's economic performance. Certain business decisions, such as decisions to make distributions of cash, require a greater than 66 2/3% ownership interest approval, and no one member owns more than a 66 2/3% interest. In April 2018, the MVP Joint Venture announced the MVP Southgate project, a proposed 70 -mile interstate pipeline that will extend from the MVP at Pittsylvania County, Virginia to new delivery points in Rockingham and Alamance Counties, North Carolina. As of September 30, 2019 , EQM owned a 47.2% interest in the MVP Southgate project and will operate the pipeline. In September 2019 , the MVP Joint Venture issued a capital call notice for the funding of the MVP project to MVP Holdco, LLC (MVP Holdco), a direct, wholly-owned subsidiary of EQM, for $254.9 million , of which $68.8 million was paid in October 2019 and $123.9 million and $62.2 million is expected to be paid in November 2019 and December 2019 , respectively. In addition, in August 2019 , the MVP Joint Venture issued a capital call notice for the funding of the MVP Southgate project to MVP Holdco for $6.2 million , of which $1.6 million was paid in October 2019 and $1.8 million and $2.8 million is expected to be paid in November 2019 and December 2019 , respectively. The capital contributions payable and the corresponding increase to the investment balance are reflected on the consolidated balance sheet as of September 30, 2019 . The interests in MVP and MVP Southgate are equity method investments for accounting purposes because EQM has the ability to exercise significant influence, but not control, over the MVP Joint Venture's operating and financial policies. Accordingly, EQM records adjustments to the investment balance for contributions to or distributions from the MVP Joint Venture and for EQM's pro-rata share of MVP Joint Venture earnings. Equity income, which is primarily related to EQM's pro-rata share of the MVP Joint Venture's AFUDC on the construction of the MVP, is reported in equity income in EQM's statements of consolidated operations. Pursuant to the MVP Joint Venture's limited liability company agreement, MVP Holdco is obligated to provide performance assurances, which may take the form of a guarantee from EQM (provided that EQM's debt is rated as investment grade in accordance with the requirements of the MVP Joint Venture's limited liability company agreement), a letter of credit or cash collateral, in favor of the MVP Joint Venture to provide assurance as to the funding of MVP Holdco's proportionate share of the construction budget for the MVP project. In January 2019, EQM issued a performance guarantee in an amount equal to 33% of EQM's proportionate share of the then-remaining construction budget for the MVP project, which was approximately $261 million at the time of issuance. As of September 30, 2019 , EQM's performance guarantee was restated to approximately $211 million , adjusted for capital contributions made during the third quarter of 2019. In October 2019, EQM issued a replacement performance guarantee in an amount equal to approximately $256 million based on the updated construction budget for the MVP project. In addition, pursuant to the MVP Joint Venture's limited liability company agreement, MVP Holdco is obligated to provide performance assurances in respect of MVP Southgate, which performance assurances may take the form of a guarantee from EQM (provided that EQM's debt is rated as investment grade in accordance with the requirements of the MVP Joint Venture's limited liability company agreement), a letter of credit or cash collateral. In February 2019, EQM issued a performance guarantee of $14 million in favor of the MVP Joint Venture for the MVP Southgate project. Upon the FERC's initial release to begin construction of the MVP Southgate project, EQM's current MVP Southgate performance guarantee will be terminated, and EQM will be obligated to issue a new guarantee (or provide another allowable form of performance assurance) in an amount equal to 33% of MVP Holdco's proportionate share of the remaining capital obligations for the MVP Southgate project under the applicable construction budget. As of September 30, 2019 , EQM's maximum financial statement exposure related to the MVP Joint Venture was approximately $2,191 million , which consists of the investment in unconsolidated entity balance on the consolidated balance sheet as of September 30, 2019 , net of capital contributions payable, and amounts that could have become due under EQM's performance guarantees as of that date. The following tables summarize the unaudited condensed consolidated financial statements of the MVP Joint Venture. Condensed Consolidated Balance Sheets September 30, December 31, (Thousands) Current assets $ 507,736 $ 687,657 Non-current assets 4,735,119 3,223,220 Total assets $ 5,242,855 $ 3,910,877 Current liabilities $ 468,011 $ 617,355 Non-current liabilities 2,416 — Equity 4,772,428 3,293,522 Total liabilities and equity $ 5,242,855 $ 3,910,877 Condensed Statements of Consolidated Operations Three Months Ended Nine Months Ended 2019 2018 2019 2018 (Thousands) Environmental remediation reserve $ (516 ) $ — $ (2,682 ) $ — Other income 1,165 1,923 5,863 3,200 Net interest income 29,100 10,036 73,035 22,674 AFUDC - equity 67,902 23,416 170,416 52,905 Net income $ 97,651 $ 35,375 $ 246,632 $ 78,779

Debt

Debt	9 Months Ended
	Sep. 30, 2019
Debt Disclosure [Abstract]
Debt	Debt $3 Billion Facility. On October 31, 2018, EQM amended and restated its unsecured revolving credit facility to increase the borrowing capacity from $1 billion to $3 billion and extend the term to October 2023 (the $3 Billion Facility). The $3 Billion Facility is available for general partnership purposes, including to purchase assets, and to fund working capital requirements and capital expenditures, pay distributions and repurchase units. Subject to satisfaction of certain conditions, the $3 Billion Facility has an accordion feature that allows EQM to increase the available borrowings under the facility by up to an additional $750 million . The $3 Billion Facility has a sublimit of up to $250 million for same-day swing line advances and a sublimit of up to $400 million for letters of credit. In addition, EQM has the ability to request that one or more lenders make available term loans under the $3 Billion Facility, subject to the satisfaction of certain conditions. As of September 30, 2019 , no term loans were outstanding under the $3 Billion Facility. Such term loans would be secured by cash and qualifying investment grade securities. EQM's $3 Billion Facility contains negative covenants that, among other things, limit restricted payments, the incurrence of debt, dispositions, mergers and fundamental changes, and transactions with affiliates. In addition, the $3 Billion Facility contains events of default such as insolvency, nonpayment of scheduled principal or interest obligations, change of control and cross-default related to the acceleration or default of certain other financial obligations. Under the $3 Billion Facility, as of the end of each fiscal quarter, EQM is required to maintain a consolidated leverage ratio of not more than 5.00 to 1.00 (or not more than 5.50 to 1.00 for certain measurement periods following the consummation of certain acquisitions). As of September 30, 2019 , EQM had approximately $265 million of borrowings outstanding and $1 million of letters of credit outstanding under the $3 Billion Facility. As of December 31, 2018 , EQM had approximately $625 million of borrowings outstanding and $1 million of letters of credit outstanding under the $3 Billion Facility. During the three and nine months ended September 30, 2019 , the maximum amount of EQM's outstanding borrowings under the $3 Billion Facility at any time was approximately $1.7 billion and the average daily balances were approximately $865 million and $950 million , respectively. EQM incurred interest at weighted average annual interest rates of approximately 3.7% and 3.8% for the three and nine months ended September 30, 2019 , respectively. During the three and nine months ended September 30, 2018 , the maximum amounts of EQM's outstanding borrowings under the $3 Billion Facility at any time were approximately $74 million and $420 million , respectively, and the average daily balances were approximately $22 million and $147 million , respectively. EQM incurred interest at weighted average annual interest rates of approximately 3.7% and 3.2% for the three and nine months ended September 30, 2018 , respectively. 2019 EQM Term Loan Agreement. In August 2019, EQM entered into a term loan agreement that provided for unsecured term loans in an aggregate principal amount of $1.4 billion (the 2019 EQM Term Loan Agreement). The initial term loans provided under the 2019 EQM Term Loan Agreement mature in August 2022. EQM received net proceeds from the issuance of the initial term loans under the 2019 EQM Term Loan Agreement of $1,397.4 million , inclusive of estimated debt issuance costs of $2.6 million . The net proceeds were primarily used to repay borrowings under the $3 Billion Facility and the remainder was used for general partnership purposes. The 2019 EQM Term Loan Agreement provides EQM with the right to request incremental term loans in an aggregate amount of up to $300 million , subject to, among other things, obtaining additional commitments from existing lenders or commitments from new lenders. EQM had $1.4 billion of borrowings outstanding under the 2019 EQM Term Loan Agreement as of September 30, 2019 . During the applicable portions of the two months ended September 30, 2019 , the weighted average annual interest rate for the period was approximately 3.6% . The 2019 EQM Term Loan Agreement contains certain negative covenants, that, among other things, limit the ability of EQM and certain of its subsidiaries to incur or permit liens on assets, establish a maximum consolidated leverage ratio of not more than 5.00 to 1.00 (or not more than 5.50 to 1.00 for certain measurement periods following the consummation of certain acquisitions) tested as of the end of each fiscal quarter, and limit transactions with affiliates, mergers and other fundamental changes, asset dispositions, and the incurrence of new debt, in each case and as applicable, subject to certain specified exceptions. The 2019 EQM Term Loan Agreement also contains certain specified events of default, including, among others, failure to make certain payments (subject to specified grace periods in some cases), failure to observe covenants (subject to specified grace periods in some cases), cross-defaults to certain other material debt, certain specified insolvency or bankruptcy events and the occurrence of a change of control event, in each case, the occurrence of which would allow the lenders to accelerate EQM's payment obligations under the 2019 EQM Term Loan Agreement. Eureka Credit Facility. Eureka Midstream, LLC (Eureka), a wholly-owned subsidiary of Eureka Midstream, has a $400 million senior secured revolving credit facility, which is available for general business purposes, including financing maintenance and expansion capital expenditures related to the Eureka system and providing working capital for Eureka’s operations (the Eureka Credit Facility). Subject to satisfaction of certain conditions, the Eureka Credit Facility has an accordion feature that allows Eureka to increase the available borrowings under the facility by an additional $100 million to an aggregate $500 million of total commitments. Under the terms of the Eureka Credit Facility, Eureka can obtain base rate loans or Eurodollar rate loans. Base rate loans are denominated in dollars and bear interest at an adjusted base rate, which was equal to the higher of (i) JPMorgan Chase Bank, N.A.'s prime rate, (ii) the one-month Adjusted Eurodollar Rate (as defined in the Eureka Credit Facility credit agreement) plus 1.0% or (iii) the Federal Funds effective rate plus 0.5% per annum; plus the Applicable Margin, as described below. Eurodollar rate loans bear interest at the Adjusted Eurodollar Rate per annum, which rate is to be determined by the administrative agent pursuant to a prescribed calculation based on the ICE Benchmark Administration LIBOR Rate plus the Applicable Margin. The Applicable Margin ranged from 0.75% to 2.0% in the case of base rate loans and from 1.75% to 3.0% in the case of Eurodollar loans, in each case, depending on the amount of the loan outstanding in relation to the borrowing base. The Eureka Credit Facility contains negative covenants that, among other things, limit restricted payments, the incurrence of debt, dispositions, mergers and fundamental changes, securities issuances, and transactions with affiliates. In addition, the Eureka Credit Facility contains events of default such as insolvency, nonpayment of scheduled principal or interest obligations, loss of material contracts, change of control and cross-default related to the acceleration or default of certain other financial obligations. Under the Eureka Credit Facility, Eureka is required to maintain a consolidated leverage ratio of not more than 4.75 to 1.00 (or not more than 5.25 to 1.00 for certain measurement periods following the consummation of certain acquisitions). Additionally, as of the end of any fiscal quarter, Eureka will not permit the ratio of consolidated EBITDA (as defined in the Eureka Credit Facility) for the four fiscal quarters then ending to consolidated interest charges to be less than 2.50 to 1.00 . As of September 30, 2019 , Eureka had approximately $293 million of borrowings outstanding under the Eureka Credit Facility. For the three months ended September 30, 2019 and for the period from April 10, 2019 through September 30, 2019 , the maximum amount of outstanding borrowings under the Eureka Credit Facility at any time was approximately $293 million for both periods, the average daily balances were approximately $293 million and $285 million , respectively, and Eureka incurred interest at a weighted average annual interest rate of approximately 4.3% for both periods. 2018 EQM Term Loan Facility . On April 25, 2018, EQM entered into a $2.5 billion unsecured multi-draw 364 -day term loan facility with a syndicate of lenders (the 2018 EQM Term Loan Facility). The 2018 EQM Term Loan Facility was used to fund the cash consideration for the Drop-Down Transaction , to repay borrowings under EQM's then-existing revolving credit facility and for other general partnership purposes. In connection with EQM's issuance of the 2018 Senior Notes (defined below), on June 25, 2018, the balance outstanding under the 2018 EQM Term Loan Facility was repaid and the 2018 EQM Term Loan Facility was terminated. As a result of the termination, EQM expensed $3 million of deferred issuance costs. From April 25, 2018 through June 25, 2018, the maximum amount of EQM's outstanding borrowings under the 2018 EQM Term Loan Facility at any time was approximately $1,825 million and the average daily balance was approximately $1,231 million . EQM incurred interest at a weighted average annual interest rate of approximately 3.3% for the period from April 25, 2018 through June 25, 2018. RMP $850 Million Facility. Prior to the completion of the EQM-RMP Merger, RM Operating LLC (formerly Rice Midstream OpCo LLC), a wholly-owned subsidiary of RMP, had an $850 million senior secured credit facility (the RMP $850 Million Facility). In connection with the completion of the EQM-RMP Merger, on July 23, 2018, EQM repaid the approximately $260 million of borrowings outstanding under the RMP $850 Million Facility and the RMP $850 Million Facility was terminated. Prior to its termination, the RMP $850 Million Facility was available for general partnership purposes, including to purchase assets, and to fund working capital requirements and capital expenditures, pay distributions and repurchase units. The RMP $850 Million Facility was secured by mortgages and other security interests on substantially all of RMP's properties and was guaranteed by RMP and its restricted subsidiaries. During the applicable portions of the three and nine months ended September 30, 2018 , the maximum outstanding borrowings were approximately $260 million and $375 million , respectively, the average daily balance was approximately $249 million and $300 million , respectively, and the weighted average annual interest rate for the period was approximately 4.1% and 3.8% , respectively. EQM 4.125% and 4.00% Senior Notes. In the fourth quarter of 2016, EQM issued $500 million aggregate principal amount of 4.125% senior unsecured notes due December 2026 (the 4.125% Senior Notes). EQM used the net proceeds from the offering to repay the then outstanding borrowings under a predecessor to the $3 Billion Facility and for general partnership purposes. In the third quarter of 2014, EQM issued $500 million aggregate principal amount of 4.00% senior unsecured notes due August 2024 (the 4.00% Senior Notes). EQM used the net proceeds from the offering to repay the outstanding borrowings under a predecessor to the $3 Billion Facility and for general partnership purposes. The 4.125% Senior Notes and the 4.00% Senior Notes were issued pursuant to supplemental indentures to EQM's existing indenture dated August 1, 2014. Both the 4.125% Senior Notes and the 4.00% Senior Notes contain covenants that limit EQM's ability to, among other things, incur certain liens securing indebtedness, engage in certain sale and leaseback transactions and enter into certain consolidations, mergers, conveyances, transfers or leases of all or substantially all of EQM's assets. 2018 Senior Notes. During the second quarter of 2018, EQM issued 4.75% senior unsecured notes due July 2023 in the aggregate principal amount of $1.1 billion , 5.50% senior unsecured notes due July 2028 in the aggregate principal amount of $850 million and 6.50% senior unsecured notes due July 2048 in the aggregate principal amount of $550 million (collectively, the 2018 Senior Notes). EQM received net proceeds from the offering of approximately $2,465.8 million , inclusive of a discount of $11.8 million and estimated debt issuance costs of approximately $22.4 million . The net proceeds were used to repay the outstanding balances under the 2018 EQM Term Loan Facility and the RMP $850 Million Facility, and the remainder was used for general partnership purposes. The 2018 Senior Notes were issued pursuant to supplemental indentures to EQM's existing indenture dated August 1, 2014. The 2018 Senior Notes contain covenants that limit EQM's ability to, among other things, incur certain liens securing indebtedness, engage in certain sale and leaseback transactions, and enter into certain consolidations, mergers, conveyances, transfers or leases of all or substantially all of EQM's assets. As of September 30, 2019 , EQM and Eureka were in compliance with all debt provisions and covenants.

Fair Value Measurements

Fair Value Measurements	9 Months Ended
	Sep. 30, 2019
Fair Value Disclosures [Abstract]
Fair Value Measurements	Fair Value Measurements The carrying values of cash and cash equivalents, accounts receivable, amounts due to/from related parties and accounts payable approximate fair value due to the short maturity of the instruments; as such, their fair values are Level 1 fair value measurements. The carrying value of the credit facility borrowings and borrowings under the 2019 EQM Term Loan Agreement approximates fair value as the interest rates are based on prevailing market rates; this is considered a Level 1 fair value measurement. As EQM's notes are not actively traded, their fair values are estimated using an income approach model that applies a discount rate based on prevailing market rates for debt with similar remaining time-to-maturity and credit risk; as such, their fair values are Level 2 fair value measurements. As of September 30, 2019 and December 31, 2018 , the estimated fair value of EQM's senior notes was approximately $3,439 million and $3,425 million , respectively, and the carrying value of EQM's senior notes was approximately $3,461 million and $3,457 million , respectively. The fair value of the Preferred Interest is a Level 3 fair value measurement and is estimated using an income approach model that applies a market-based discount rate. As of September 30, 2019 and December 31, 2018 , the estimated fair value of the Preferred Interest was approximately $128 million and $122 million , respectively, and the carrying value of the Preferred Interest was approximately $111 million and $115 million , respectively.

Net Income per Limited Partner

Net Income per Limited Partner Unit and Cash Distributions	9 Months Ended
	Sep. 30, 2019
Earnings Per Share [Abstract]
Net Income per Limited Partner Unit and Cash Distributions	Equity The following table summarizes changes in EQM's Series A Preferred Units, common units and Class B units, each representing limited partner interests in EQM, and general partner units during the year ended December 31, 2018 and from January 1, 2019 through September 30, 2019 . Limited Partner Interests Series A Preferred Units Common Units Class B Units General Partner Units Total Balance at January 1, 2018 — 80,581,758 — 1,443,015 82,024,773 Common units issued (1) — 10,821 — — 10,821 Drop-Down Transaction consideration — 5,889,282 — — 5,889,282 Common units issued in the EQM-RMP Merger — 33,975,777 — — 33,975,777 Balance at December 31, 2018 — 120,457,638 — 1,443,015 121,900,653 Unit cancellation — (8 ) — — (8 ) EQM IDR Transaction (2) — 80,000,000 7,000,000 (1,443,015 ) 85,556,985 Issuance of Series A Preferred Units 24,605,291 — — — 24,605,291 Balance at September 30, 2019 24,605,291 200,457,630 7,000,000 — 232,062,921 (1) Units issued upon the resignation of a member of the Board of Directors of EQM's general partner. (2) In exchange for the cancellation of the EQM IDRs, EQM issued 87,000,000 EQM common units (the Exchange Consideration) to the Former EQM General Partner. At the effective time of the EQM IDR Merger, (i) the Exchange Consideration held by the Former EQM General Partner was canceled, (ii) 80,000,000 EQM common units and 7,000,000 Class B units were issued on a pro rata basis to certain affiliates of Equitrans Midstream, and (iii) 21,811,643 EQM common units held by EQGP were canceled and 21,811,643 EQM common units were issued pro rata to certain affiliates of Equitrans Midstream. As of September 30, 2019 , Equitrans Gathering Holdings, LLC (Equitrans Gathering Holdings), EQM GP Corporation (EQM GP Corp) and Equitrans Midstream Holdings, LLC (EMH), each a wholly-owned subsidiary of Equitrans Midstream, held 89,505,616 , 89,536 and 27,650,303 EQM common units, respectively. Additionally, Equitrans Gathering Holdings, EQM GP Corp and EMH held 6,153,907 , 6,155 and 839,938 Class B units, respectively. As of September 30, 2019 , Equitrans Midstream owned, directly or indirectly, 117,245,455 EQM common units and 7,000,000 Class B units (collectively representing, after taking into account the Series A Preferred Units issued in the Private Placement on an as-converted basis, a 53.5% limited partner interest in EQM) and the entire non-economic general partner interest in EQM, while the public owned a 46.5% limited partner interest in EQM. Class B Units As discussed above and in Note 1 , in February 2019, EQM issued 7,000,000 Class B units representing a new class of limited partner interests in EQM as partial consideration for the EQM IDR Transaction. The Class B units are substantially similar in all respects to EQM's common units, except that the Class B units are not entitled to receive distributions of available cash until the applicable Class B unit conversion date (or, if earlier, a change of control). The Class B units are divided into three tranches, with the first tranche of 2,500,000 Class B units becoming convertible at the holder’s option into EQM common units on April 1, 2021, the second tranche of 2,500,000 Class B units becoming convertible at the holder’s option into EQM common units on April 1, 2022, and the third tranche of 2,000,000 Class B units becoming convertible at the holder’s option into EQM common units on April 1, 2023 (each, a Class B unit conversion date). Additionally, the Class B units will become convertible at the holder’s option into EQM common units immediately before a change of control of EQM. After the applicable Class B unit conversion date (or, if earlier, a change of control), whether or not such Class B units have been converted into EQM common units, the Class B units will participate pro rata with the EQM common units in distributions of available cash. The holders of Class B units vote together with the holders of EQM common units as a single class, except that Class B units owned by the general partner of EQM and its affiliates are excluded from voting if EQM common units owned by such parties are excluded from voting. Holders of Class B units are entitled to vote as a separate class on any matter that adversely affects the rights or preferences of the Class B units in relation to other classes of EQM partnership interests in any material respect or as required by law. Series A Preferred Units As discussed in Note 1 , in March 2019, EQM entered into the Preferred Unit Purchase Agreement with certain investors to issue and sell in the Private Placement an aggregate of 24,605,291 Series A Preferred Units representing limited partner interests in EQM for a cash purchase price of $48.77 per Series A Preferred Unit, resulting in total gross proceeds of approximately $1.2 billion . The net proceeds from the Private Placement were used in part to fund the purchase price in the Bolt-on Acquisition and to pay certain fees and expenses related to the Bolt-on Acquisition, and the remainder was used for general partnership purposes. The Private Placement closed concurrently with the closing of the Bolt-on Acquisition on April 10, 2019 . The Series A Preferred Units rank senior to all common units and Class B units representing limited partner interests in EQM with respect to distribution rights and rights upon liquidation. The Series A Preferred Units vote on an as-converted basis with the EQM common units and Class B units and have certain other class voting rights with respect to any amendment to EQM's partnership agreement or its certificate of limited partnership that would be adverse (other than in a de minimis manner) to any of the rights, preferences or privileges of the Series A Preferred Units. The holders of the Series A Preferred Units are entitled to receive cumulative quarterly distributions at a rate of $1.0364 per Series A Preferred Unit for the first twenty distribution periods, and thereafter the quarterly distributions on the Series A Preferred Units will be an amount per Series A Preferred Unit for such quarter equal to (i) the Series A Preferred Unit purchase price of $48.77 per such unit, multiplied by (ii) a percentage equal to the sum of (A) the greater of (x) the 3-month LIBOR as of the second London banking day prior to the beginning of the applicable quarter and (y) 2.59% , and (B) 6.90% , multiplied by (iii) 25% . EQM will not be entitled to pay any distributions on any junior securities, including any EQM common units, prior to paying the quarterly distributions payable to the holders of Series A Preferred Units, including any previously accrued and unpaid distributions. Each holder of the Series A Preferred Units may elect to convert all or any portion of the Series A Preferred Units owned by it into EQM common units initially on a one-for-one basis, subject to customary anti-dilution adjustments and an adjustment for any distributions that have accrued but have not been paid when due and partial period distributions, at any time (but not more often than once per fiscal quarter) after April 10, 2021 (or earlier upon the liquidation, dissolution or winding up of EQM), provided that any conversion is for at least $30 million (calculated based on the closing price of the EQM common units on the trading day preceding notice of conversion) or such lesser amount if such conversion relates to all of a holder’s remaining Series A Preferred Units. EQM may elect to convert all or any portion of the Series A Preferred Units into EQM common units at any time (but not more often than once per quarter) after April 10, 2021 if (i) the common units are listed for, or admitted to, trading on a national securities exchange, (ii) the closing price per common unit on the national securities exchange on which the common units are listed for, or admitted to, trading exceeds 140% of the Series A Preferred Unit purchase price of $48.77 per such unit for the 20 consecutive trading days immediately preceding notice of the conversion, (iii) the average daily trading volume of the common units on the national securities exchange on which the common units are listed for, or admitted to, trading exceeds 500,000 common units for the 20 consecutive trading days immediately preceding notice of the conversion, (iv) EQM has an effective registration statement on file with the SEC covering resales of the common units to be received by such holders upon any such conversion and (v) EQM has paid all accrued quarterly distributions in cash to the holders. In addition, upon certain events involving a change in control, the holders of Series A Preferred Units may elect, among other potential elections, to convert their preferred units into EQM common units at a certain conversion rate. Net Income per Limited Partner Unit and Cash Distributions Net Income per Limited Partner Unit. Net income per limited partner unit is calculated utilizing the two-class method by dividing the limited partner interest in net income by the weighted average number of limited partner units outstanding during the period. The two-class method uses an earnings allocation method under which earnings per limited partner unit are calculated for each class of common unit and any participating security considering all distributions declared and participation rights in undistributed earnings as if all earnings had been distributed during the period. Diluted net income per limited partner unit reflects the potential dilution that could occur if securities or agreements to issue common units were exercised, settled or converted into EQM common units. EQM uses the if-converted method to compute potential common units from phantom units granted to independent and non-employee directors and to compute potential common units related to the conversion of Series A Preferred Units and Class B units. Under the if-converted method, dilutive convertible securities are assumed to be converted from the date of the issuance, and the resulting common units are included in the denominator of the diluted net income per unit calculation for the period being presented. Each series of potential common units is evaluated in sequence from the most dilutive to the least dilutive. Distributions declared in the period and undeclared distributions on the cumulative Series A Preferred Units that accumulated during the period are added back to the numerator for purposes of the if-converted calculation. As a result of the EQM IDR Transaction, EQM’s common unitholders are entitled to all distributions until the Class B units are converted to common units (other than distributions in respect of the Series A Preferred Units). Class B unitholders have no rights to distributions until the Class B units are convertible into common units. Accordingly, for all periods prior to the date such Class B units are convertible, the Class B units are not considered participating securities under the two-class method. In addition, the Series A Preferred Units are not considered a participating security as they only have distribution rights up to the specified per-unit quarterly distribution and have no rights to EQM’s undistributed earnings prior to conversion of the Series A Preferred Units into EQM common units, as discussed in Note 5 . For the three and nine months ended September 30, 2019 , limited partner interest in net income, which excludes the Series A Preferred Units interest in net income, was fully allocated to EQM’s common unitholders. For the three and nine months ended September 30, 2018 , net income attributable to EQM was allocated to the general partner and limited partners in accordance with their respective ownership percentages. Any common units issued during the relevant periods are included on a monthly weighted-average basis for the periods in which they were outstanding. The phantom units granted to the independent and non-employee directors of EQM's general partner will be paid in common units on a director’s termination of service on the Board of Directors of EQM's general partner. The weighted average phantom unit awards included in the calculation of basic weighted average limited partner units outstanding were 25,305 and 17,816 for the three months ended September 30, 2019 and 2018 , respectively, and 23,687 and 19,699 for the nine months ended September 30, 2019 and 2018, respectively. The following table presents EQM's calculation of net income per limited partner unit for common and Class B limited partner units. Three Months Ended Nine Months Ended 2019 2018 (1) 2019 2018 (1) (Thousands, except per unit data) Net (loss) income attributable to EQM $ (10,518 ) $ 209,927 $ 393,851 $ 704,109 Less: Series A Preferred Units interest in net income (25,501 ) — (48,480 ) — Less: pre-acquisition net income allocated to EQT — (8,490 ) — (164,242 ) Less: general partner interest in net income – general partner units — (2,379 ) — (7,145 ) Less: general partner interest in net income – IDRs — (70,967 ) — (183,253 ) Limited partner interest in net (loss) income $ (36,019 ) $ 128,091 $ 345,371 $ 349,469 Net (loss) income allocable to common units $ (36,019 ) $ 128,091 $ 345,371 $ 349,469 Net (loss) income allocable to Class B units $ — $ — $ — $ — Weighted average limited partner common units outstanding - basic 200,483 111,980 185,244 93,746 Weighted average limited partner common units outstanding - diluted (2) 200,483 111,980 192,244 93,746 Net (loss) income per limited partner common unit - basic $ (0.18 ) $ 1.14 $ 1.86 $ 3.73 Net (loss) income per limited partner common unit - diluted $ (0.18 ) $ 1.14 $ 1.80 $ 3.73 (1) Net income attributable to the Drop-Down Transaction and the EQM-RMP Merger for the periods prior to May 1, 2018 and July 23, 2018, respectively, was not allocated to the limited partners for purposes of calculating net income per limited partner unit as these pre-acquisition amounts were not available to the EQM unitholders. (2) In periods when EQM reports a net loss, the Class B and Series A Preferred Units are excluded from the calculation of diluted weighted average units outstanding because of their anti-dilutive effect on loss per unit. For the three months ended September 30, 2019 , 7,000,000 Class B units and 24,605,291 Series A Preferred Units were excluded in the calculation of diluted weighted average limited partner units outstanding as the effect of these units were anti-dilutive. For the nine months ended September 30, 2019 , 7,000,000 Class B units were included in the calculation of diluted weighted average limited partner units outstanding based upon the application of the if-converted method. The effect of Series A Preferred Units was anti-dilutive. Distributions to common unitholders. On October 21, 2019 , the Board of Directors of EQM's general partner declared a cash distribution to EQM's unitholders for the third quarter of 2019 of $1.160 per common unit. The cash distribution will be paid on November 13, 2019 to common unitholders of record at the close of business on November 1, 2019 . Cash distributions paid by EQM to Equitrans Midstream will be approximately $136.0 million related to Equitrans Midstream's limited partner interest in EQM. Distributions to Series A Preferred Unit holders. On October 21, 2019 , the Board of Directors of EQM's general partner declared a quarterly cash distribution on the Series A Preferred Units for the third quarter of 2019 of $1.0364 per Series A Preferred Unit. The cash distribution will be paid on November 13, 2019 to Series A Preferred unitholders of record at the close of business on November 1, 2019 . For the quarter ended September 30, 2019 , no distributions were declared on the Class B units as none of these units were convertible into EQM common units.

Financial Statements (Policies)

Financial Statements (Policies)	9 Months Ended
	Sep. 30, 2019
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Organization and Basis of Presentation	Organization EQM is a growth-oriented Delaware limited partnership formed by EQT in January 2012. Prior to the completion of the EQM IDR Transaction (defined below), EQM Midstream Services, LLC was the general partner of EQM (the Former EQM General Partner). Following the consummation of the EQM IDR Transaction, EQGP Services, LLC, a wholly-owned indirect subsidiary of Equitrans Midstream, became the general partner of EQM (the New EQM General Partner). References in these consolidated financial statements to Equitrans Midstream refer collectively to Equitrans Midstream Corporation and its consolidated subsidiaries, as applicable. On February 21, 2018, EQT announced its plan to separate its midstream business, which was composed of the separately-operated natural gas gathering, transmission and storage and water services operations of EQT (collectively, the Midstream Business), from its upstream business, which was composed of the natural gas, oil and natural gas liquids development, production and sales and commercial operations of EQT (collectively, the Upstream Business) (the Separation). On November 12, 2018, the Separation was effected through a series of transactions that culminated in EQT's contribution of the Midstream Business to Equitrans Midstream. On February 22, 2019, Equitrans Midstream completed a simplification transaction pursuant to that certain Agreement and Plan of Merger, dated as of February 13, 2019 (the IDR Merger Agreement), by and among Equitrans Midstream and certain related parties, pursuant to which, among other things, (i) Equitrans Merger Sub, LP, a party to the IDR Merger Agreement, merged with and into EQGP (the Merger) with EQGP continuing as the surviving limited partnership and a wholly-owned subsidiary of EQM following the Merger, and (ii) each of (a) the IDRs, (b) the economic portion of the general partner interest in EQM and (c) the issued and outstanding EQGP common units representing limited partner interests in EQGP were canceled, and, as consideration for such cancellation, certain affiliates of Equitrans Midstream received on a pro rata basis 80,000,000 newly-issued EQM common units and 7,000,000 newly-issued Class B units (Class B units), both representing limited partner interests in EQM, and the New EQM General Partner retained the non-economic general partner interest in EQM (the EQM IDR Transaction). Additionally, as part of the EQM IDR Transaction, the 21,811,643 EQM common units held by EQGP were canceled and 21,811,643 EQM common units were issued pro rata to certain affiliates of Equitrans Midstream. See Note 5 for further information on the EQM IDR Transaction and Class B Units. The EQM IDR Transaction constituted an exchange of equity interests between entities under common control and not a transfer of a business. Therefore, the exchange resulted in a reclassification, as of February 22, 2019, of a $43.8 million deficit capital balance from the general partner line item to the common and Class B line items in EQM's consolidated balance sheets based on the respective limited partner ownership interests. The reclassification represented an allocation of the carrying value of the exchanged general partner interest. Prior to the EQM IDR Transaction, when distributions related to the general partner interest and IDRs were made, earnings equal to the amount of distributions were allocated to the general partner before the remaining earnings were allocated to the limited partner unitholders based on their respective ownership percentages. Subsequent to the EQM IDR Transaction, no earnings are allocated to the general partner. The allocation of net income attributable to EQM for purposes of calculating net income per limited partner unit is described in Note 12 . On March 13, 2019, EQM entered into a Convertible Preferred Unit Purchase Agreement (inclusive of certain Joinder Agreements entered into on March 18, 2019, the Preferred Unit Purchase Agreement) with certain investors to issue and sell in a private placement (the Private Placement) an aggregate of 24,605,291 Series A Perpetual Convertible Preferred Units (Series A Preferred Units) representing limited partner interests in EQM for a cash purchase price of $48.77 per Series A Preferred Unit, resulting in total gross proceeds of approximately $1.2 billion . The net proceeds from the Private Placement were used in part to fund the purchase price in the Bolt-on Acquisition (defined in Note 2 ) and to pay certain fees and expenses related to the Bolt-on Acquisition, and the remainder was used for general partnership purposes. The Private Placement closed concurrently with the closing of the Bolt-on Acquisition on April 10, 2019 . See Note 5 for further information on the Series A Preferred Units and the Bolt-on Acquisition. Following the EQM IDR Transaction and the closing of the Private Placement, and as of September 30, 2019 , Equitrans Midstream held a 53.5% limited partner interest (after taking into account the Series A Preferred Units issued in the Private Placement on an as-converted basis) and the non-economic general partner interest in EQM. See Note 5 for further information on the EQM IDR Transaction and Private Placement. Basis of Presentation EQM's consolidated financial statements have been retrospectively recast to include the pre-acquisition results of the Drop-Down Transaction and the EQM-RMP Merger because these transactions represented business combinations between entities under common control. The recast is for the period the acquired businesses were under the common control of EQT, which began on November 13, 2017 as a result of EQT's acquisition of Rice Energy Inc. (Rice) (the Rice Merger). EQM recorded the assets and liabilities acquired in the Drop-Down Transaction and the EQM-RMP Merger at their carrying amounts to EQT on the effective dates of the transactions. The consolidated financial statements are not necessarily indicative of the actual results of operations if EQM and the assets acquired in the Drop-Down Transaction and the EQM-RMP Merger had been operated together during the pre-acquisition periods. Following the completion of the Bolt-on Acquisition, EQM evaluated Eureka Midstream for consolidation and determined that Eureka Midstream does not meet the criteria for variable interest entity classification due to its ability to independently finance its operations through the Eureka Credit Facility (as defined in Note 10 ), as well as each member having proportional voting rights through their equity investments. As such, as of September 30, 2019 , EQM consolidates Eureka Midstream using the voting interest model, recording noncontrolling interest related to the third-party ownership interests in Eureka Midstream. The accompanying unaudited consolidated financial statements have been prepared in accordance with GAAP for interim financial information and with the requirements of Form 10-Q and Article 10 of Regulation S-X. Accordingly, they do not include all of the information and footnotes required by GAAP for complete financial statements. In the opinion of management, these unaudited consolidated financial statements include all adjustments (consisting of only normal, recurring adjustments, unless otherwise disclosed in this Form 10-Q) necessary for a fair presentation of the financial position of EQM as of September 30, 2019 and December 31, 2018 , the results of its operations and equity for the three and nine months ended September 30, 2019 and 2018 , and its cash flows for the nine months ended September 30, 2019 and 2018 . The balance sheet at December 31, 2018 has been derived from the audited financial statements at that date but does not include all of the information and notes required by GAAP for complete financial statements. Due to the seasonal nature of EQM's utility customer contracts, the interim statements for the three and nine months ended September 30, 2019 are not necessarily indicative of the results that may be expected for the year ending December 31, 2019 . EQM and its subsidiaries, including Eureka Midstream, do not have any employees. Operational, management and other services for EQM and its subsidiaries are provided by the directors and officers of the New EQM General Partner and employees of Equitrans Midstream. For further information, refer to the consolidated financial statements and related notes for the year ended December 31, 2018, as well as "Management's Discussion and Analysis of Financial Condition and Results of Operations" contained herein.
Recently Issued Accounting Standards	Recently Issued Accounting Standards In February 2016, the FASB issued ASU 2016-02, Leases . The standard requires entities to record assets and obligations for contracts currently recognized as operating leases. In July 2018, the FASB issued ASU 2018-11, Leases (Topic 842): Targeted Improvements . The update provides an optional transition method of adoption that permits entities to initially apply the standard at the adoption date and recognize a cumulative-effect adjustment to the opening balance of retained earnings in the period of adoption. Under the optional transition method, comparative financial information and disclosures are not required. The update also provides transition practical expedients. The standard requires disclosures of the nature, maturity and value of an entity's lease liabilities and elections taken by the entity. In March 2019, the FASB issued ASU 2019-01, Leases (Topic 842): Codification Improvements , which, among other things, clarifies interim disclosure requirements in the year of ASU 2016-02 adoption. EQM adopted ASU 2016-02, ASU 2018-11 and ASU 2019-01 on January 1, 2019 using the optional transition method. EQM uses a lease accounting system to monitor its current population of lease contracts. EQM implemented processes and controls to review new lease contracts for appropriate accounting treatment in the context of the standards and to generate disclosures required under the standards. For the disclosures required by the standards, see Note 4 . In June 2016, the FASB issued ASU 2016-13, Financial Instruments-Credit Losses: Measurement of Credit Losses on Financial Instruments. The standard amends guidance on reporting credit losses for assets held at amortized cost basis and available for sale debt securities. For assets held at amortized cost basis, this standard eliminates the probable initial recognition threshold in current GAAP, and, in its place, requires an entity to recognize its current estimate of all expected credit losses. The amendments affect loans, debt securities, trade receivables, net investments in leases, off balance sheet credit exposures, reinsurance receivables, and any other financial assets not excluded from the scope of the standard that have the contractual right to receive cash. The standard will be effective for annual reporting periods beginning after December 15, 2019, including interim periods within that reporting period. EQM is currently evaluating the effect this standard will have on its financial statements and related disclosures. In August 2018, the FASB issued ASU 2018-13, Fair Value Measurement, Changes to the Disclosure Requirements for Fair Value Measurement , which makes a number of changes to the hierarchy associated with Level 1, 2 and 3 fair value measurements and the related disclosure requirements. This guidance is effective for fiscal years beginning after December 15, 2019, including interim periods within those fiscal years. Early adoption is permitted. EQM is currently evaluating the effect this standard will have on its financial statements and related disclosures but does not expect the adoption of this standard to have a material effect on its financial statements and related disclosures. In August 2018, the FASB issued ASU 2018-15, Intangibles—Goodwill and Other: Internal-Use Software , which aligns the requirements for capitalizing implementation costs incurred in a hosting arrangement that is a service contract with the requirements for capitalizing implementation costs incurred to develop or obtain internal-use software (and hosting arrangements that include an internal-use software license). This guidance is effective for fiscal years beginning after December 15, 2019, including interim periods within those fiscal years. EQM early-adopted the standard using the prospective method of adoption on January 1, 2019. Following the adoption of ASU 2018-15, EQM began capitalizing certain implementation costs related to cloud computing arrangements that are service contracts. The capitalized portion of these costs are included in the property, plant and equipment line on the consolidated balance sheets and will be amortized over the term of EQM's hosting arrangement. For the three and nine months ended September 30, 2019 , EQM did no t recognize any amortization expense related to implementation costs on its cloud computing arrangements as such assets were not in use. The costs will be included in the selling, general and administrative expense line on the accompanying statements of consolidated operations when recognized. In August 2018, the SEC adopted a final rule under SEC Release No. 33-10532, Disclosure Update and Simplification
Impairment of Long-Lived Assets	EQM evaluates long-lived assets, including related intangibles, for impairment when events or changes in circumstances indicate, in management's judgment, that the carrying value of such assets may not be recoverable. Asset recoverability is measured by comparing the carrying value of the asset or asset group with its expected future pre-tax undiscounted cash flows. These cash flow estimates require EQM to make projections and assumptions for many years into the future for pricing, demand, competition, operating cost and other factors. If the carrying amount exceeds the expected future undiscounted cash flows, EQM recognizes an impairment equal to the excess of net book value over fair value as determined by quoted market prices in active markets or present value techniques if quotes are unavailable. The determination of the fair value using present value techniques requires EQM to make projections and assumptions regarding the probability of a range of outcomes and the rates of interest used in the present value calculations. Any changes EQM makes to these projections and assumptions could result in significant revisions to its evaluation of recoverability of its property, plant and equipment and the recognition of additional impairments.

Acquisitions, Mergers and Div_2

Acquisitions, Mergers and Divestitures (Tables)	9 Months Ended
	Sep. 30, 2019
Business Acquisition [Line Items]
Schedule Fair Value of Assets Acquired and Liabilities Assumed	The following table summarizes the allocation of the fair value of the assets and liabilities of RMP, EQM Olympus, Strike Force and EQM WV as of November 13, 2017 through pushdown accounting from EQT, as well as certain measurement period adjustments made subsequent to EQT's initial valuation. Goodwill and Purchase Price Allocation (Thousands) Estimated fair value of RMP, EQM Olympus, Strike Force (a) and EQM WV $ 4,014,984 Estimated Fair Value of Assets Acquired and Liabilities Assumed: Current assets (b) 132,459 Intangible assets (c) 623,200 Property and equipment, net (d) 2,265,900 Other non-current assets 118 Current liabilities (b) (117,124 ) RMP $850 Million Facility (e) (266,000 ) Other non-current liabilities (e) (9,323 ) Total estimated fair value of assets acquired and liabilities assumed 2,629,230 Goodwill as of November 13, 2017 (f) 1,385,754 Impairment of goodwill (g) 261,941 Goodwill as of December 31, 2018 1,123,813 Impairment of goodwill (h) 161,595 Goodwill as of September 30, 2019 $ 962,218 (a) Includes the estimated fair value attributable to noncontrolling interest in Strike Force of $166 million. (b) The fair value of current assets and current liabilities was assumed to approximate their carrying values. (c) The identifiable intangible assets for customer relationships were estimated by applying a discounted cash flow approach which was adjusted for customer attrition assumptions and projected market conditions. (d) The estimated fair value of long-lived property and equipment were determined utilizing estimated replacement cost adjusted for a usage or obsolescence factor. (e) The estimated fair value of long-term liabilities was determined utilizing observable market inputs where available or estimated based on their then current carrying values. (f) Reflected the value of perceived growth opportunities, synergies and operating leverage anticipated through the acquisitions and ownership of the acquired gathering assets as of November 13, 2017. (g) During its annual goodwill assessment for the year ended December 31, 2018, EQM determined that the carrying value of the RMP PA Gas Gathering (as defined in Note 3) reporting unit, which comprises the Pennsylvania gathering assets acquired in the Rice Merger, was greater than its fair value. As a result, EQM recognized an impairment to goodwill of approximately $261.9 million. (h) As discussed above, during the third quarter of 2019, EQM identified impairment indicators that suggested the fair value of its goodwill was more likely than not below its carrying amount. As such, EQM performed an interim goodwill impairment assessment, which resulted in EQM recognizing an impairment to goodwill of approximately $261.3 million, of which $161.6 million was associated with its RMP PA Gas Gathering reporting unit. As of September 30, 2019, EQM’s goodwill balance was reduced to $962.2 million, including $923.4 million and $38.8 million associated with RMP PA Gas Gathering and Rice Retained Midstream (as defined in Note 3), respectively. See Note 3 for further detail.
Schedule of Finite-lived Intangible Assets	Intangible assets, net as of September 30, 2019 , are detailed below. (in thousands) As of September 30, 2019 Intangible assets $ 311,000 Less: impairment of Hornet-related intangible assets (a) 36,405 Less: accumulated amortization 7,517 Intangible assets, net $ 267,078 (a) See Note 3 for disclosure regarding impairments of long-lived assets.
Schedule of Unaudited Pro Forma Combined Financial Information	Subsequent to the completion of the Bolt-on Acquisition, Eureka Midstream and Hornet Midstream collectively contributed the following to both the Gathering segment and EQM's consolidated operating results for the period from April 10, 2019 through September 30, 2019 . (in thousands) (unaudited) April 10, 2019 through September 30, 2019 Operating revenues $ 61,579 Operating loss attributable to EQM $ (109,277 ) Net loss attributable to noncontrolling interests $ (25,664 ) Net loss attributable to EQM $ (87,949 ) Unaudited Pro Forma Information. The following unaudited pro forma combined financial information presents EQM's results as though the EQM IDR Transaction and Bolt-on Acquisition had been completed at January 1, 2018. The pro forma combined financial information has been included for comparative purposes and is not necessarily indicative of the results that might have actually occurred had the EQM IDR Transaction and Bolt-on Acquisition taken place on January 1, 2018; furthermore, the financial information is not intended to be a projection of future results. (in thousands, except per unit data)(unaudited) Nine Months Ended September 30, 2019 Pro forma operating revenues $ 1,235,963 Pro forma net income $ 396,339 Pro forma net loss attributable to noncontrolling interests $ (22,447 ) Pro forma net income attributable to EQM $ 418,786 Pro forma income per limited partner common unit (basic) $ 1.85 Pro forma income per limited partner common unit (diluted) $ 1.78 (in thousands, except per unit data)(unaudited) Three Months Ended September 30, 2018 Nine Months Ended September 30, 2018 Pro forma operating revenues $ 391,151 $ 1,195,096 Pro forma net income $ 221,037 $ 730,440 Pro forma net income attributable to noncontrolling interests $ 4,752 $ 13,462 Pro forma net income attributable to EQM $ 216,285 $ 716,978 Pro forma income per unit (basic) $ 0.95 $ 3.20 Pro forma income per unit (diluted) $ 0.92 $ 3.09
Bolt-on Acquisition
Business Acquisition [Line Items]
Schedule Fair Value of Assets Acquired and Liabilities Assumed	<div style="font-family:Times New Roman;font-size:10pt;"><div style="line-height:120%;padding-top:12px;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">The following table summarizes the allocation of the fair value of the assets acquired and liabilities assumed in the Bolt-on Acquisition as of April 10, 2019 by EQM, as well as certain measurement period adjustments made subsequent to EQM's initial valuation.</font></div><div style="line-height:120%;padding-top:12px;text-align:center;font-size:10pt;"><div style="padding-left:0px;text-indent:0px;line-height:normal;padding-top:10px;"><table cellpadding="0" cellspacing="0" style="font-family:Times New Roman;font-size:10pt;margin-left:auto;margin-right:auto;width:100%;border-collapse:collapse;text-align:left;"><tr><td colspan="13" rowspan="1"></td></tr><tr><td style="width:43%;" rowspan="1" colspan="1"></td><td style="width:1%;" rowspan="1" colspan="1"></td><td style="width:1%;" rowspan="1" colspan="1"></td><td style="width:16%;" rowspan="1" colspan="1"></td><td style="width:1%;" rowspan="1" colspan="1"></td><td style="width:1%;" rowspan="1" colspan="1"></td><td style="width:1%;" rowspan="1" colspan="1"></td><td style="width:16%;" rowspan="1" colspan="1"></td><td style="width:1%;" rowspan="1" colspan="1"></td><td style="width:1%;" rowspan="1" colspan="1"></td><td style="width:1%;" rowspan="1" colspan="1"></td><td style="width:16%;" rowspan="1" colspan="1"></td><td style="width:1%;" rowspan="1" colspan="1"></td></tr><tr><td style="vertical-align:bottom;background-color:#cceeff;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;" rowspan="1" colspan="1"><div style="text-align:left;font-size:9pt;"><font style="font-family:inherit;font-size:9pt;">(in thousands)</font></div></td><td style="vertical-align:bottom;background-color:#cceeff;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;" rowspan="1" colspan="1"><div style="overflow:hidden;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;"> </font></div></td><td colspan="3" style="vertical-align:bottom;background-color:#cceeff;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;" rowspan="1"><div style="text-align:center;font-size:9pt;"><font style="font-family:inherit;font-size:9pt;font-weight:bold;">Preliminary Purchase Price Allocation</font></div><div style="text-align:center;font-size:9pt;"><font style="font-family:inherit;font-size:9pt;font-weight:bold;">(As initially reported)</font></div></td><td style="vertical-align:bottom;background-color:#cceeff;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;" rowspan="1" colspan="1"><div style="overflow:hidden;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;"> </font></div></td><td colspan="3" style="vertical-align:bottom;background-color:#cceeff;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;" rowspan="1"><div style="text-align:center;font-size:9pt;"><font style="font-family:inherit;font-size:9pt;font-weight:bold;">Measurement Period Adjustments</font><font style="font-family:inherit;font-size:9pt;font-weight:bold;"><sup style="vertical-align:top;line-height:120%;font-size:6pt">(a)</sup></font></div></td><td style="vertical-align:bottom;background-color:#cceeff;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;" rowspan="1" colspan="1"><div style="overflow:hidden;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;"> </font></div></td><td colspan="3" style="vertical-align:bottom;background-color:#cceeff;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;" rowspan="1"><div style="text-align:center;font-size:9pt;"><font style="font-family:inherit;font-size:9pt;font-weight:bold;">Preliminary Purchase Price Allocation</font></div><div style="text-align:center;font-size:9pt;"><font style="font-family:inherit;font-size:9pt;font-weight:bold;">(As adjusted)</font></div></td></tr><tr><td style="vertical-align:bottom;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;" rowspan="1" colspan="1"><div style="text-align:left;font-size:9pt;"><font style="font-family:inherit;font-size:9pt;font-weight:bold;">Consideration given:</font></div></td><td style="vertical-align:bottom;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;" rowspan="1" colspan="1"><div style="overflow:hidden;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;"> </font></div></td><td colspan="3" style="vertical-align:bottom;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;" rowspan="1"><div style="overflow:hidden;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;"> </font></div></td><td style="vertical-align:bottom;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;" rowspan="1" colspan="1"><div style="overflow:hidden;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;"> </font></div></td><td colspan="3" style="vertical-align:bottom;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;" rowspan="1"><div style="overflow:hidden;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;"> </font></div></td><td style="vertical-align:bottom;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;" rowspan="1" colspan="1"><div style="overflow:hidden;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;"> </font></div></td><td colspan="3" style="vertical-align:bottom;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;" rowspan="1"><div style="overflow:hidden;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;"> </font></div></td></tr><tr><td style="vertical-align:bottom;background-color:#cceeff;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;" rowspan="1" colspan="1"><div style="font-size:9pt;"><font style="font-family:inherit;font-size:9pt;">Cash consideration</font><font style="font-family:inherit;font-size:9pt;"><sup style="vertical-align:top;line-height:120%;font-size:6pt">(b)</sup></font></div></td><td style="vertical-align:bottom;background-color:#cceeff;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;" rowspan="1" colspan="1"><div style="overflow:hidden;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;"> </font></div></td><td style="vertical-align:bottom;padding-left:2px;padding-top:2px;padding-bottom:2px;background-color:#cceeff;" rowspan="1" colspan="1"><div style="text-align:left;font-size:9pt;"><font style="font-family:inherit;font-size:9pt;">$</font></div></td><td style="vertical-align:bottom;background-color:#cceeff;padding-top:2px;padding-bottom:2px;" rowspan="1" colspan="1"><div style="text-align:right;font-size:9pt;"><font style="font-family:inherit;font-size:9pt;">861,250</font></div></td><td style="vertical-align:bottom;background-color:#cceeff;" rowspan="1" colspan="1"><div style="text-align:left;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;"><br clear="none"/></font></div></td><td style="vertical-align:bottom;background-color:#cceeff;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;" rowspan="1" colspan="1"><div style="overflow:hidden;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;"> </font></div></td><td style="vertical-align:bottom;padding-left:2px;padding-top:2px;padding-bottom:2px;background-color:#cceeff;" rowspan="1" colspan="1"><div style="text-align:left;font-size:9pt;"><font style="font-family:inherit;font-size:9pt;">$</font></div></td><td style="vertical-align:bottom;background-color:#cceeff;padding-top:2px;padding-bottom:2px;" rowspan="1" colspan="1"><div style="text-align:right;font-size:9pt;"><font style="font-family:inherit;font-size:9pt;">(11,404</font></div></td><td style="vertical-align:bottom;background-color:#cceeff;padding-right:2px;padding-top:2px;padding-bottom:2px;" rowspan="1" colspan="1"><div style="text-align:left;font-size:9pt;"><font style="font-family:inherit;font-size:9pt;">)</font></div></td><td style="vertical-align:bottom;background-color:#cceeff;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;" rowspan="1" colspan="1"><div style="overflow:hidden;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;"> </font></div></td><td style="vertical-align:bottom;padding-left:2px;padding-top:2px;padding-bottom:2px;background-color:#cceeff;" rowspan="1" colspan="1"><div style="text-align:left;font-size:9pt;"><font style="font-family:inherit;font-size:9pt;">$</font></div></td><td style="vertical-align:bottom;background-color:#cceeff;padding-top:2px;padding-bottom:2px;" rowspan="1" colspan="1"><div style="text-align:right;font-size:9pt;"><font style="font-family:inherit;font-size:9pt;">849,846</font></div></td><td style="vertical-align:bottom;background-color:#cceeff;" rowspan="1" colspan="1"><div style="text-align:left;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;"><br clear="none"/></font></div></td></tr><tr><td style="vertical-align:bottom;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;" rowspan="1" colspan="1"><div style="text-align:left;font-size:9pt;"><font style="font-family:inherit;font-size:9pt;">Buyout of Eureka Midstream Class B Units and incentive compensation</font></div></td><td style="vertical-align:bottom;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;" rowspan="1" colspan="1"><div style="overflow:hidden;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;"> </font></div></td><td colspan="2" style="vertical-align:bottom;border-bottom:1px solid #000000;padding-left:2px;padding-top:2px;padding-bottom:2px;" rowspan="1"><div style="text-align:right;font-size:9pt;"><font style="font-family:inherit;font-size:9pt;">2,530</font></div></td><td style="vertical-align:bottom;border-bottom:1px solid #000000;" rowspan="1" colspan="1"><div style="text-align:left;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;"><br clear="none"/></font></div></td><td style="vertical-align:bottom;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;" rowspan="1" colspan="1"><div style="overflow:hidden;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;"> </font></div></td><td colspan="2" style="vertical-align:bottom;border-bottom:1px solid #000000;padding-left:2px;padding-top:2px;padding-bottom:2px;" rowspan="1"><div style="text-align:right;font-size:9pt;"><font style="font-family:inherit;font-size:9pt;">—</font></div></td><td style="vertical-align:bottom;border-bottom:1px solid #000000;" rowspan="1" colspan="1"><div style="text-align:left;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;"><br clear="none"/></font></div></td><td style="vertical-align:bottom;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;" rowspan="1" colspan="1"><div style="overflow:hidden;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;"> </font></div></td><td colspan="2" style="vertical-align:bottom;border-bottom:1px solid #000000;padding-left:2px;padding-top:2px;padding-bottom:2px;" rowspan="1"><div style="text-align:right;font-size:9pt;"><font style="font-family:inherit;font-size:9pt;">2,530</font></div></td><td style="vertical-align:bottom;border-bottom:1px solid #000000;" rowspan="1" colspan="1"><div style="text-align:left;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;"><br clear="none"/></font></div></td></tr><tr><td style="vertical-align:bottom;background-color:#cceeff;padding-left:12px;padding-top:2px;padding-bottom:2px;padding-right:2px;" rowspan="1" colspan="1"><div style="text-align:left;font-size:9pt;"><font style="font-family:inherit;font-size:9pt;">Total consideration</font></div></td><td style="vertical-align:bottom;background-color:#cceeff;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;" rowspan="1" colspan="1"><div style="overflow:hidden;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;"> </font></div></td><td colspan="2" style="vertical-align:bottom;background-color:#cceeff;padding-left:2px;padding-top:2px;padding-bottom:2px;" rowspan="1"><div style="text-align:right;font-size:9pt;"><font style="font-family:inherit;font-size:9pt;">863,780</font></div></td><td style="vertical-align:bottom;background-color:#cceeff;" rowspan="1" colspan="1"><div style="text-align:left;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;"><br clear="none"/></font></div></td><td style="vertical-align:bottom;background-color:#cceeff;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;" rowspan="1" colspan="1"><div style="overflow:hidden;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;"> </font></div></td><td colspan="2" style="vertical-align:bottom;background-color:#cceeff;padding-left:2px;padding-top:2px;padding-bottom:2px;" rowspan="1"><div style="text-align:right;font-size:9pt;"><font style="font-family:inherit;font-size:9pt;">(11,404</font></div></td><td style="vertical-align:bottom;background-color:#cceeff;padding-right:2px;padding-top:2px;padding-bottom:2px;" rowspan="1" colspan="1"><div style="text-align:left;font-size:9pt;"><font style="font-family:inherit;font-size:9pt;">)</font></div></td><td style="vertical-align:bottom;background-color:#cceeff;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;" rowspan="1" colspan="1"><div style="overflow:hidden;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;"> </font></div></td><td colspan="2" style="vertical-align:bottom;background-color:#cceeff;padding-left:2px;padding-top:2px;padding-bottom:2px;" rowspan="1"><div style="text-align:right;font-size:9pt;"><font style="font-family:inherit;font-size:9pt;">852,376</font></div></td><td style="vertical-align:bottom;background-color:#cceeff;" rowspan="1" colspan="1"><div style="text-align:left;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;"><br clear="none"/></font></div></td></tr><tr><td style="vertical-align:bottom;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;" rowspan="1" colspan="1"><div style="overflow:hidden;height:17px;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;"> </font></div></td><td style="vertical-align:bottom;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;" rowspan="1" colspan="1"><div style="overflow:hidden;height:17px;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;"> </font></div></td><td colspan="3" style="vertical-align:bottom;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;" rowspan="1"><div style="overflow:hidden;height:17px;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;"> </font></div></td><td style="vertical-align:bottom;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;" rowspan="1" colspan="1"><div style="overflow:hidden;height:17px;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;"> </font></div></td><td colspan="3" style="vertical-align:bottom;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;" rowspan="1"><div style="overflow:hidden;height:17px;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;"> </font></div></td><td style="vertical-align:bottom;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;" rowspan="1" colspan="1"><div style="overflow:hidden;height:17px;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;"> </font></div></td><td colspan="3" style="vertical-align:bottom;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;" rowspan="1"><div style="overflow:hidden;height:17px;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;"> </font></div></td></tr><tr><td style="vertical-align:bottom;background-color:#cceeff;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;" rowspan="1" colspan="1"><div style="text-align:left;font-size:9pt;"><font style="font-family:inherit;font-size:9pt;font-weight:bold;">Fair value of liabilities assumed:</font></div></td><td style="vertical-align:bottom;background-color:#cceeff;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;" rowspan="1" colspan="1"><div style="overflow:hidden;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;"> </font></div></td><td colspan="3" style="vertical-align:bottom;background-color:#cceeff;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;" rowspan="1"><div style="overflow:hidden;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;"> </font></div></td><td style="vertical-align:bottom;background-color:#cceeff;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;" rowspan="1" colspan="1"><div style="overflow:hidden;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;"> </font></div></td><td colspan="3" style="vertical-align:bottom;background-color:#cceeff;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;" rowspan="1"><div style="overflow:hidden;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;"> </font></div></td><td style="vertical-align:bottom;background-color:#cceeff;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;" rowspan="1" colspan="1"><div style="overflow:hidden;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;"> </font></div></td><td colspan="3" style="vertical-align:bottom;background-color:#cceeff;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;" rowspan="1"><div style="overflow:hidden;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;"> </font></div></td></tr><tr><td style="vertical-align:bottom;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;" rowspan="1" colspan="1"><div style="text-align:left;font-size:9pt;"><font style="font-family:inherit;font-size:9pt;">Current liabilities</font></div></td><td style="vertical-align:bottom;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;" rowspan="1" colspan="1"><div style="overflow:hidden;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;"> </font></div></td><td colspan="2" style="vertical-align:bottom;padding-left:2px;padding-top:2px;padding-bottom:2px;" rowspan="1"><div style="text-align:right;font-size:9pt;"><font style="font-family:inherit;font-size:9pt;">52,458</font></div></td><td style="vertical-align:bottom;" rowspan="1" colspan="1"><div style="text-align:left;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;"><br clear="none"/></font></div></td><td style="vertical-align:bottom;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;" rowspan="1" colspan="1"><div style="overflow:hidden;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;"> </font></div></td><td colspan="2" style="vertical-align:bottom;padding-left:2px;padding-top:2px;padding-bottom:2px;" rowspan="1"><div style="text-align:right;font-size:9pt;"><font style="font-family:inherit;font-size:9pt;">(9,857</font></div></td><td style="vertical-align:bottom;padding-right:2px;padding-top:2px;padding-bottom:2px;" rowspan="1" colspan="1"><div style="text-align:left;font-size:9pt;"><font style="font-family:inherit;font-size:9pt;">)</font></div></td><td style="vertical-align:bottom;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;" rowspan="1" colspan="1"><div style="overflow:hidden;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;"> </font></div></td><td colspan="2" style="vertical-align:bottom;padding-left:2px;padding-top:2px;padding-bottom:2px;" rowspan="1"><div style="text-align:right;font-size:9pt;"><font style="font-family:inherit;font-size:9pt;">42,601</font></div></td><td style="vertical-align:bottom;" rowspan="1" colspan="1"><div style="text-align:left;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;"><br clear="none"/></font></div></td></tr><tr><td style="vertical-align:bottom;background-color:#cceeff;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;" rowspan="1" colspan="1"><div style="text-align:left;font-size:9pt;"><font style="font-family:inherit;font-size:9pt;">Long-term debt</font></div></td><td style="vertical-align:bottom;background-color:#cceeff;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;" rowspan="1" colspan="1"><div style="overflow:hidden;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;"> </font></div></td><td colspan="2" style="vertical-align:bottom;background-color:#cceeff;padding-left:2px;padding-top:2px;padding-bottom:2px;" rowspan="1"><div style="text-align:right;font-size:9pt;"><font style="font-family:inherit;font-size:9pt;">300,825</font></div></td><td style="vertical-align:bottom;background-color:#cceeff;" rowspan="1" colspan="1"><div style="text-align:left;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;"><br clear="none"/></font></div></td><td style="vertical-align:bottom;background-color:#cceeff;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;" rowspan="1" colspan="1"><div style="overflow:hidden;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;"> </font></div></td><td colspan="2" style="vertical-align:bottom;background-color:#cceeff;padding-left:2px;padding-top:2px;padding-bottom:2px;" rowspan="1"><div style="text-align:right;font-size:9pt;"><font style="font-family:inherit;font-size:9pt;">—</font></div></td><td style="vertical-align:bottom;background-color:#cceeff;" rowspan="1" colspan="1"><div style="text-align:left;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;"><br clear="none"/></font></div></td><td style="vertical-align:bottom;background-color:#cceeff;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;" rowspan="1" colspan="1"><div style="overflow:hidden;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;"> </font></div></td><td colspan="2" style="vertical-align:bottom;background-color:#cceeff;padding-left:2px;padding-top:2px;padding-bottom:2px;" rowspan="1"><div style="text-align:right;font-size:9pt;"><font style="font-family:inherit;font-size:9pt;">300,825</font></div></td><td style="vertical-align:bottom;background-color:#cceeff;" rowspan="1" colspan="1"><div style="text-align:left;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;"><br clear="none"/></font></div></td></tr><tr><td style="vertical-align:bottom;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;" rowspan="1" colspan="1"><div style="text-align:left;font-size:9pt;"><font style="font-family:inherit;font-size:9pt;">Other long-term liabilities</font></div></td><td style="vertical-align:bottom;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;" rowspan="1" colspan="1"><div style="overflow:hidden;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;"> </font></div></td><td colspan="2" style="vertical-align:bottom;border-bottom:1px solid #000000;padding-left:2px;padding-top:2px;padding-bottom:2px;" rowspan="1"><div style="text-align:right;font-size:9pt;"><font style="font-family:inherit;font-size:9pt;">10,203</font></div></td><td style="vertical-align:bottom;border-bottom:1px solid #000000;" rowspan="1" colspan="1"><div style="text-align:left;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;"><br clear="none"/></font></div></td><td style="vertical-align:bottom;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;" rowspan="1" colspan="1"><div style="overflow:hidden;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;"> </font></div></td><td colspan="2" style="vertical-align:bottom;border-bottom:1px solid #000000;padding-left:2px;padding-top:2px;padding-bottom:2px;" rowspan="1"><div style="text-align:right;font-size:9pt;"><font style="font-family:inherit;font-size:9pt;">—</font></div></td><td style="vertical-align:bottom;border-bottom:1px solid #000000;" rowspan="1" colspan="1"><div style="text-align:left;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;"><br clear="none"/></font></div></td><td style="vertical-align:bottom;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;" rowspan="1" colspan="1"><div style="overflow:hidden;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;"> </font></div></td><td colspan="2" style="vertical-align:bottom;border-bottom:1px solid #000000;padding-left:2px;padding-top:2px;padding-bottom:2px;" rowspan="1"><div style="text-align:right;font-size:9pt;"><font style="font-family:inherit;font-size:9pt;">10,203</font></div></td><td style="vertical-align:bottom;border-bottom:1px solid #000000;" rowspan="1" colspan="1"><div style="text-align:left;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;"><br clear="none"/></font></div></td></tr><tr><td style="vertical-align:bottom;background-color:#cceeff;padding-left:12px;padding-top:2px;padding-bottom:2px;padding-right:2px;" rowspan="1" colspan="1"><div style="text-align:left;font-size:9pt;"><font style="font-family:inherit;font-size:9pt;">Amount attributable to liabilities assumed</font></div></td><td style="vertical-align:bottom;background-color:#cceeff;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;" rowspan="1" colspan="1"><div style="overflow:hidden;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;"> </font></div></td><td colspan="2" style="vertical-align:bottom;background-color:#cceeff;padding-left:2px;padding-top:2px;padding-bottom:2px;" rowspan="1"><div style="text-align:right;font-size:9pt;"><font style="font-family:inherit;font-size:9pt;">363,486</font></div></td><td style="vertical-align:bottom;background-color:#cceeff;" rowspan="1" colspan="1"><div style="text-align:left;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;"><br clear="none"/></font></div></td><td style="vertical-align:bottom;background-color:#cceeff;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;" rowspan="1" colspan="1"><div style="overflow:hidden;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;"> </font></div></td><td colspan="2" style="vertical-align:bottom;background-color:#cceeff;padding-left:2px;padding-top:2px;padding-bottom:2px;" rowspan="1"><div style="text-align:right;font-size:9pt;"><font style="font-family:inherit;font-size:9pt;">(9,857</font></div></td><td style="vertical-align:bottom;background-color:#cceeff;padding-right:2px;padding-top:2px;padding-bottom:2px;" rowspan="1" colspan="1"><div style="text-align:left;font-size:9pt;"><font style="font-family:inherit;font-size:9pt;">)</font></div></td><td style="vertical-align:bottom;background-color:#cceeff;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;" rowspan="1" colspan="1"><div style="overflow:hidden;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;"> </font></div></td><td colspan="2" style="vertical-align:bottom;background-color:#cceeff;padding-left:2px;padding-top:2px;padding-bottom:2px;" rowspan="1"><div style="text-align:right;font-size:9pt;"><font style="font-family:inherit;font-size:9pt;">353,629</font></div></td><td style="vertical-align:bottom;background-color:#cceeff;" rowspan="1" colspan="1"><div style="text-align:left;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;"><br clear="none"/></font></div></td></tr><tr><td style="vertical-align:bottom;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;" rowspan="1" colspan="1"><div style="overflow:hidden;height:17px;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;"> </font></div></td><td style="vertical-align:bottom;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;" rowspan="1" colspan="1"><div style="overflow:hidden;height:17px;font-size:10pt;">&l

Leases (Tables)

Leases (Tables)	9 Months Ended
	Sep. 30, 2019
Leases [Abstract]
Schedule of Operating Lease Cost	The following table summarizes operating lease cost for the three and nine months ended September 30, 2019 . Three Months Ended September 30, 2019 Nine Months Ended (Thousands) Operating lease cost $ 2,838 $ 6,987 Short-term lease cost 1,473 3,353 Variable lease cost 100 112 Total lease cost $ 4,411 $ 10,452
Schedule of Operating Lease Liability Maturities	The following table summarizes undiscounted cash flows owed by EQM to lessors pursuant to contractual agreements in effect as of September 30, 2019 and related imputed interest. The majority of EQM's lease agreements have multiple renewal periods at EQM's option; however, because none of the renewal periods are reasonably assured to be exercised, the associated operating lease payments have not been included in the table below. September 30, 2019 (Thousands) 2019 $ 3,218 2020 12,168 2021 9,913 2022 7,694 2023 5,607 2024 3,966 Thereafter 24,728 Total 67,294 Less: imputed interest 13,926 Present value of operating lease liability $ 53,368

Equity (Tables)

Equity (Tables)	9 Months Ended
	Sep. 30, 2019
Equity [Abstract]
Summary of Units Issued	The following table summarizes changes in EQM's Series A Preferred Units, common units and Class B units, each representing limited partner interests in EQM, and general partner units during the year ended December 31, 2018 and from January 1, 2019 through September 30, 2019 . Limited Partner Interests Series A Preferred Units Common Units Class B Units General Partner Units Total Balance at January 1, 2018 — 80,581,758 — 1,443,015 82,024,773 Common units issued (1) — 10,821 — — 10,821 Drop-Down Transaction consideration — 5,889,282 — — 5,889,282 Common units issued in the EQM-RMP Merger — 33,975,777 — — 33,975,777 Balance at December 31, 2018 — 120,457,638 — 1,443,015 121,900,653 Unit cancellation — (8 ) — — (8 ) EQM IDR Transaction (2) — 80,000,000 7,000,000 (1,443,015 ) 85,556,985 Issuance of Series A Preferred Units 24,605,291 — — — 24,605,291 Balance at September 30, 2019 24,605,291 200,457,630 7,000,000 — 232,062,921 (1) Units issued upon the resignation of a member of the Board of Directors of EQM's general partner. (2) In exchange for the cancellation of the EQM IDRs, EQM issued 87,000,000 EQM common units (the Exchange Consideration) to the Former EQM General Partner. At the effective time of the EQM IDR Merger, (i) the Exchange Consideration held by the Former EQM General Partner was canceled, (ii) 80,000,000 EQM common units and 7,000,000 Class B units were issued on a pro rata basis to certain affiliates of Equitrans Midstream, and (iii) 21,811,643 EQM common units held by EQGP were canceled and 21,811,643 EQM common units were issued pro rata to certain affiliates of Equitrans Midstream.

Financial Information by Busi_2

Financial Information by Business Segment (Tables)	9 Months Ended
	Sep. 30, 2019
Segment Reporting [Abstract]
Schedule of Revenue from External Customers and Operating Income and Reconciliation to Net Income	Three Months Ended Nine Months Ended 2019 2018 2019 2018 (Thousands) Revenues from customers: Gathering $ 299,491 $ 252,861 $ 847,038 $ 731,440 Transmission 87,299 89,350 289,926 285,429 Water 21,644 22,373 67,419 93,438 Total operating revenues $ 408,434 $ 364,584 $ 1,204,383 $ 1,110,307 Operating (loss) income: Gathering (a) $ (98,489 ) $ 177,902 $ 177,720 $ 510,755 Transmission 59,690 58,691 207,684 198,784 Water 7,722 (3,093 ) 18,980 35,627 Total operating (loss) income $ (31,077 ) $ 233,500 $ 404,384 $ 745,166 Reconciliation of operating (loss) income to net (loss) income: Equity income (b) $ 44,448 $ 16,087 $ 112,293 $ 35,836 Other income 337 1,345 4,506 3,193 Net interest expense 53,923 41,005 152,996 76,740 Net (loss) income $ (40,215 ) $ 209,927 $ 368,187 $ 707,455 (a) Impairments of long-lived assets of $298.7 million and $378.8 million for the three and nine months ended September 30, 2019, respectively, were included in Gathering operating (loss) income. See Note 3 for further information. (b) Equity income is included in the Transmission segment.
Schedule of Segment Assets	September 30, December 31, (Thousands) Segment assets: Gathering $ 7,949,204 $ 6,011,654 Transmission (a) 3,801,905 3,066,659 Water 198,672 237,602 Total operating segments 11,949,781 9,315,915 Headquarters, including cash 204,256 140,206 Total assets $ 12,154,037 $ 9,456,121 (a) The equity investment in the MVP Joint Venture is included in the Transmission segment.
Schedule of Depreciation, Amortization, and Expenditures for Segment Assets	Three Months Ended Nine Months Ended 2019 2018 2019 2018 (Thousands) Depreciation: Gathering $ 38,943 $ 25,359 $ 104,502 $ 72,309 Transmission 13,347 12,357 38,474 37,228 Water 6,907 5,851 19,801 17,420 Total $ 59,197 $ 43,567 $ 162,777 $ 126,957 Expenditures for segment assets: Gathering (a)(b) $ 272,138 $ 194,477 $ 745,053 $ 515,072 Transmission (c) 16,296 37,626 46,287 84,517 Water 13,466 7,981 31,490 17,358 Total (d) $ 301,900 $ 240,084 $ 822,830 $ 616,947 (a) Includes approximately $0.3 million and $58.9 million for the three and nine months ended September 30, 2019 , respectively, related to non-operating assets acquired from Equitrans Midstream in the Shared Assets Transaction that primarily support EQM's gathering activities. (b) Includes approximately $6.7 million and $17.6 million of capital expenditures related to noncontrolling interests in Eureka Midstream for the three and nine months ended September 30, 2019 , respectively. (c) Transmission capital expenditures do not include capital contributions made to the MVP Joint Venture for the MVP and MVP Southgate projects of approximately $211.7 million and $263.2 million for the three months ended September 30, 2019 and 2018 , respectively, and approximately $512.9 million and $446.0 million for the nine months ended September 30, 2019 and 2018 , respectively. (d) EQM accrues capital expenditures when the work has been completed but the associated bills have not yet been paid. Accrued capital expenditures are excluded from the statements of consolidated cash flows until they are paid. Accrued capital expenditures were approximately $115.5 million , $110.8 million and $108.9 million at September 30, 2019 , June 30, 2019 and December 31, 2018 , respectively. Accrued capital expenditures were approximately $91.3 million , $84.6 million and $90.7 million at September 30, 2018 , June 30, 2018 and December 31, 2017 , respectively. On April 10, 2019, as a result of the Bolt-on Acquisition, EQM assumed $8.8 million of Eureka Midstream accrued capital expenditures.

Revenue from Contracts with C_2

Revenue from Contracts with Customers (Tables)	9 Months Ended
	Sep. 30, 2019
Revenue from Contract with Customer [Abstract]
Schedule of Disaggregated Revenue Information, by Business Segment	The tables below provide disaggregated revenue information by business segment. Three Months Ended September 30, 2019 Gathering Transmission Water Total (Thousands) Firm reservation fee revenues $ 154,791 $ 81,990 $ — $ 236,781 Volumetric-based fee revenues 144,700 5,309 — 150,009 Water services revenues — — 21,644 21,644 Total operating revenues $ 299,491 $ 87,299 $ 21,644 $ 408,434 Three Months Ended September 30, 2018 Gathering Transmission Water Total (Thousands) Firm reservation fee revenues $ 112,598 $ 82,669 $ — $ 195,267 Volumetric-based fee revenues 140,263 6,681 — 146,944 Water services revenues — — 22,373 22,373 Total operating revenues $ 252,861 $ 89,350 $ 22,373 $ 364,584 Nine Months Ended September 30, 2019 Gathering Transmission Water Total (Thousands) Firm reservation fee revenues $ 431,520 $ 263,051 $ — $ 694,571 Volumetric-based fee revenues 415,518 26,875 — 442,393 Water services revenues — — 67,419 67,419 Total operating revenues $ 847,038 $ 289,926 $ 67,419 $ 1,204,383 Nine Months Ended September 30, 2018 Gathering Transmission Water Total (Thousands) Firm reservation fee revenues $ 334,233 $ 262,666 $ — $ 596,899 Volumetric-based fee revenues 397,207 22,763 — 419,970 Water services revenues — — 93,438 93,438 Total operating revenues $ 731,440 $ 285,429 $ 93,438 $ 1,110,307
Summary of Remaining Performance Obligations	The following table summarizes the transaction price allocated to EQM's remaining performance obligations under all contracts with firm reservation fees and MVCs as of September 30, 2019 . 2019 (a) 2020 2021 2022 2023 Thereafter Total (Thousands) Gathering firm reservation fees $ 124,735 $ 512,126 $ 586,691 $ 591,430 $ 590,342 $ 2,152,476 $ 4,557,800 Gathering revenues supported by MVCs 41,341 133,969 153,065 153,065 152,242 626,548 1,260,230 Transmission firm reservation fees 92,853 348,324 374,627 370,617 332,393 2,731,561 4,250,375 Total $ 258,929 $ 994,419 $ 1,114,383 $ 1,115,112 $ 1,074,977 $ 5,510,585 $ 10,068,405 (a)

Investment in Unconsolidated _2

Investment in Unconsolidated Entity (Tables)	9 Months Ended
	Sep. 30, 2019
Equity Method Investments and Joint Ventures [Abstract]
Schedule of Unaudited Condensed Financial Statements for the Investment in Unconsolidated Equity	The following tables summarize the unaudited condensed consolidated financial statements of the MVP Joint Venture. Condensed Consolidated Balance Sheets September 30, December 31, (Thousands) Current assets $ 507,736 $ 687,657 Non-current assets 4,735,119 3,223,220 Total assets $ 5,242,855 $ 3,910,877 Current liabilities $ 468,011 $ 617,355 Non-current liabilities 2,416 — Equity 4,772,428 3,293,522 Total liabilities and equity $ 5,242,855 $ 3,910,877 Condensed Statements of Consolidated Operations Three Months Ended Nine Months Ended 2019 2018 2019 2018 (Thousands) Environmental remediation reserve $ (516 ) $ — $ (2,682 ) $ — Other income 1,165 1,923 5,863 3,200 Net interest income 29,100 10,036 73,035 22,674 AFUDC - equity 67,902 23,416 170,416 52,905 Net income $ 97,651 $ 35,375 $ 246,632 $ 78,779

Net Income per Limited Partne_2

Net Income per Limited Partner Unit and Cash Distributions (Tables)	9 Months Ended
	Sep. 30, 2019
Earnings Per Share [Abstract]
Schedule of Earnings Per Share, Diluted	The following table presents EQM's calculation of net income per limited partner unit for common and Class B limited partner units. Three Months Ended Nine Months Ended 2019 2018 (1) 2019 2018 (1) (Thousands, except per unit data) Net (loss) income attributable to EQM $ (10,518 ) $ 209,927 $ 393,851 $ 704,109 Less: Series A Preferred Units interest in net income (25,501 ) — (48,480 ) — Less: pre-acquisition net income allocated to EQT — (8,490 ) — (164,242 ) Less: general partner interest in net income – general partner units — (2,379 ) — (7,145 ) Less: general partner interest in net income – IDRs — (70,967 ) — (183,253 ) Limited partner interest in net (loss) income $ (36,019 ) $ 128,091 $ 345,371 $ 349,469 Net (loss) income allocable to common units $ (36,019 ) $ 128,091 $ 345,371 $ 349,469 Net (loss) income allocable to Class B units $ — $ — $ — $ — Weighted average limited partner common units outstanding - basic 200,483 111,980 185,244 93,746 Weighted average limited partner common units outstanding - diluted (2) 200,483 111,980 192,244 93,746 Net (loss) income per limited partner common unit - basic $ (0.18 ) $ 1.14 $ 1.86 $ 3.73 Net (loss) income per limited partner common unit - diluted $ (0.18 ) $ 1.14 $ 1.80 $ 3.73 (1) Net income attributable to the Drop-Down Transaction and the EQM-RMP Merger for the periods prior to May 1, 2018 and July 23, 2018, respectively, was not allocated to the limited partners for purposes of calculating net income per limited partner unit as these pre-acquisition amounts were not available to the EQM unitholders. (2) In periods when EQM reports a net loss, the Class B and Series A Preferred Units are excluded from the calculation of diluted weighted average units outstanding because of their anti-dilutive effect on loss per unit. For the three months ended September 30, 2019 , 7,000,000 Class B units and 24,605,291 Series A Preferred Units were excluded in the calculation of diluted weighted average limited partner units outstanding as the effect of these units were anti-dilutive. For the nine months ended September 30, 2019 , 7,000,000 Class B units were included in the calculation of diluted weighted average limited partner units outstanding based upon the application of the if-converted method. The effect of Series A Preferred Units was anti-dilutive.
Schedule of Earnings Per Share, Basic	The following table presents EQM's calculation of net income per limited partner unit for common and Class B limited partner units. Three Months Ended Nine Months Ended 2019 2018 (1) 2019 2018 (1) (Thousands, except per unit data) Net (loss) income attributable to EQM $ (10,518 ) $ 209,927 $ 393,851 $ 704,109 Less: Series A Preferred Units interest in net income (25,501 ) — (48,480 ) — Less: pre-acquisition net income allocated to EQT — (8,490 ) — (164,242 ) Less: general partner interest in net income – general partner units — (2,379 ) — (7,145 ) Less: general partner interest in net income – IDRs — (70,967 ) — (183,253 ) Limited partner interest in net (loss) income $ (36,019 ) $ 128,091 $ 345,371 $ 349,469 Net (loss) income allocable to common units $ (36,019 ) $ 128,091 $ 345,371 $ 349,469 Net (loss) income allocable to Class B units $ — $ — $ — $ — Weighted average limited partner common units outstanding - basic 200,483 111,980 185,244 93,746 Weighted average limited partner common units outstanding - diluted (2) 200,483 111,980 192,244 93,746 Net (loss) income per limited partner common unit - basic $ (0.18 ) $ 1.14 $ 1.86 $ 3.73 Net (loss) income per limited partner common unit - diluted $ (0.18 ) $ 1.14 $ 1.80 $ 3.73 (1) Net income attributable to the Drop-Down Transaction and the EQM-RMP Merger for the periods prior to May 1, 2018 and July 23, 2018, respectively, was not allocated to the limited partners for purposes of calculating net income per limited partner unit as these pre-acquisition amounts were not available to the EQM unitholders. (2) In periods when EQM reports a net loss, the Class B and Series A Preferred Units are excluded from the calculation of diluted weighted average units outstanding because of their anti-dilutive effect on loss per unit. For the three months ended September 30, 2019 , 7,000,000 Class B units and 24,605,291 Series A Preferred Units were excluded in the calculation of diluted weighted average limited partner units outstanding as the effect of these units were anti-dilutive. For the nine months ended September 30, 2019 , 7,000,000 Class B units were included in the calculation of diluted weighted average limited partner units outstanding based upon the application of the if-converted method. The effect of Series A Preferred Units was anti-dilutive.

Financial Statements (Details)

Financial Statements (Details) - USD ($)		Mar. 13, 2019	Feb. 22, 2019	Feb. 13, 2019	Feb. 28, 2019	Sep. 30, 2019	Mar. 31, 2019		Sep. 30, 2019	Dec. 31, 2018
Cloud Computing Arrangements
Class of Stock [Line Items]
Amortization expense related to implementation costs						$ 0			$ 0
Common Units
Class of Stock [Line Items]
Canceled common units (in shares)				21,811,643
General Partner
Class of Stock [Line Items]
Exchange of equity interests			$ (43,800,000)				$ (43,782,000)	[1]
EQM | Common Units | EQGP
Class of Stock [Line Items]
Partners' capital common units outstanding (in shares)				21,811,643		21,811,643			21,811,643
EQM | Common Units | Equitrans Midstream Holdings, LLC
Class of Stock [Line Items]
Limited partner ownership interest									53.50%
Class B Units
Class of Stock [Line Items]
Canceled common units (in shares)						7,000,000			7,000,000	0
Class B Units | Common Units
Class of Stock [Line Items]
Exchange of equity interests	[1]						$ 1,477,000
IDR Merger Agreement
Class of Stock [Line Items]
Newly-issued common units (in shares)				80,000,000					80,000,000
IDR Merger Agreement | Class B Units
Class of Stock [Line Items]
Newly-issued common units (in shares)				7,000,000	7,000,000				7,000,000
Private Placement
Class of Stock [Line Items]
Aggregate number of units owned (in shares)		24,605,291
Cash purchase price for Series A Preferred Units (in dollars per share)		$ 48.77
Consideration received on transaction		$ 1,200,000,000
[1]	As discussed in Notes 1 and 2 , the consolidated financial statements of EQM have been retrospectively recast to include the pre-acquisition results of the Drop-Down Transaction and the EQM-RMP Merger because these transactions were between entities under common control.

Acquisitions, Mergers and Div_3

Acquisitions, Mergers and Divestitures - Narrative (Details)		Oct. 01, 2019	Sep. 30, 2019USD ($)	Aug. 14, 2019USD ($)compressor_stationmi	Apr. 10, 2019USD ($)mi	Mar. 31, 2019USD ($)	May 01, 2018USD ($)shares	Apr. 25, 2018USD ($)reporting_unitshares	Nov. 13, 2017USD ($)	Sep. 30, 2019USD ($)		Jun. 30, 2019USD ($)	Sep. 30, 2018USD ($)		Sep. 30, 2019USD ($)	Sep. 30, 2019USD ($)reporting_unit		Sep. 30, 2018USD ($)		Dec. 31, 2018USD ($)	Nov. 01, 2018USD ($)	Jun. 30, 2018
Business Acquisition [Line Items]
Limited partner ownership interest (as a percent)													25.00%					25.00%				25.00%
Payment of related interest and fees																$ 28,325,000		$ 0
Interest, net of amount capitalized	[1]															192,298,000		42,652,000
Separation and other transaction costs	[2]									$ 256,000			$ 2,161,000			19,127,000		7,511,000
Goodwill	[3]		$ 962,218,000							962,218,000					$ 962,218,000	962,218,000				$ 1,123,813,000
Amortization of intangible assets	[2]									14,540,000			10,387,000			$ 38,677,000	[1]	31,160,000	[1]
Purchase of assets						$ 49,700,000						$ 8,900,000
Number of reporting units | reporting_unit								2								3
Impairments of long-lived assets										298,652,000	[2],[4]	$ 80,100,000	$ 0	[2],[4]		$ 378,787,000	[2],[4],[5]	$ 0	[2],[4],[5]
EQM Credit Facility | Line of credit
Business Acquisition [Line Items]
Credit facility																					$ 3,000,000,000
Strike Force Midstream
Business Acquisition [Line Items]
Limited partner ownership interest							100.00%
Eureka Midstream Holdings, LLC
Business Acquisition [Line Items]
Limited partner ownership interest (as a percent)					60.00%
Length of gathering lines (in miles) | mi					190
Hornet Midstream Holdings, LLC
Business Acquisition [Line Items]
Limited partner ownership interest (as a percent)					100.00%
Length of gathering lines (in miles) | mi					15
Payment of related interest and fees					$ 28,200,000
Interest, net of amount capitalized					100,000
Bolt-on Acquisition
Business Acquisition [Line Items]
Total consideration					1,040,000,000
Cash consideration			852,376,000		863,780,000
Assumed pro-rata debt					192,000,000
Separation and other transaction costs										300,000						17,000,000
Acquisition-related expenses										300,000						15,300,000
Acquisition-related expenses, professional fees																1,700,000
Goodwill			0		113,642,000					0					0	0
Non-controlling interest acquired, fair value			478,460,000		$ 486,062,000					478,460,000					478,460,000	478,460,000
Estimated useful life					20 years
Intangible asset impairment										36,405,000
Annual increase in amortization expense										1,000,000
Amortization of intangible assets										4,100,000					(400,000)	7,500,000
Estimated annual amortization expense, 2019			4,200,000							4,200,000					4,200,000	4,200,000
Estimated annual amortization expense, 2020			16,800,000							16,800,000					16,800,000	16,800,000
Estimated annual amortization expense, 2021			16,800,000							16,800,000					16,800,000	16,800,000
Estimated annual amortization expense, 2022			16,800,000							16,800,000					16,800,000	16,800,000
Estimated annual amortization expense, 2023			16,800,000							16,800,000					16,800,000	16,800,000
Estimated annual amortization expense, 2024			16,800,000							16,800,000					16,800,000	16,800,000
EQM-RMP Merger
Business Acquisition [Line Items]
Total consideration									$ 4,014,984,000
Goodwill			962,218,000						1,385,754,000	962,218,000					962,218,000	962,218,000				$ 1,123,813,000
Non-controlling interest acquired, fair value									$ 166,000,000
EQM-RMP Merger | Rice Midstream Partners, LP
Business Acquisition [Line Items]
Common share conversation ratio								0.3319
Equity interest issued or issuable (in shares) | shares								33,975,777
EQM-RMP Merger | EQM | EQT
Business Acquisition [Line Items]
Equity interest issued or issuable (in shares) | shares								9,544,530
May 2018 Acquisition
Business Acquisition [Line Items]
Cash consideration							$ 1,150,000,000
Equity interest issued or issuable (in shares) | shares							5,889,282
May 2018 Acquisition | Strike Force Midstream | Strike Force Midstream Holdings LLC
Business Acquisition [Line Items]
Limited partner ownership interest							75.00%
EQM-RMP Merger and Drop-Down Transaction
Business Acquisition [Line Items]
Goodwill								$ 1,384,900,000
Strike Force Midstream
Business Acquisition [Line Items]
Limited partner ownership interest (as a percent)							25.00%
Total consideration							$ 175,000,000
Disposal Group, Not Discontinued Operations | Copley Gathering System
Business Acquisition [Line Items]
Length of gathering lines (in miles) | mi				530
Impairments of long-lived assets	[2],[4]									80,100,000
Number of assets | compressor_station				4
Purchase price of divestitures				$ 1,000
Subsequent Event | Bolt-on Acquisition
Business Acquisition [Line Items]
Estimated useful life		7 years 3 months
Gathering | Bolt-on Acquisition
Business Acquisition [Line Items]
Goodwill			$ 99,700,000							$ 99,700,000					$ 99,700,000	$ 99,700,000
[1]	As discussed in Notes 1 and 2 , the consolidated financial statements of EQM have been retrospectively recast to include the pre-acquisition results of the Drop-Down Transaction and the EQM-RMP Merger because these transactions were between entities under common control.
[2]	As discussed in Notes 1 and 2 , the consolidated financial statements of EQM have been retrospectively recast to include the pre-acquisition results of EQM Olympus Midstream LLC (EQM Olympus), Strike Force Midstream Holdings LLC (Strike Force) and EQM West Virginia Midstream LLC (EQM WV), which were acquired by EQM effective on May 1, 2018 (the Drop-Down Transaction), and RM Partners LP (RMP), which was acquired by EQM effective on July 23, 2018 (the EQM-RMP Merger), because these transactions were between entities under common control.
[3]	See Note 3 for disclosure regarding impairments of goodwill.
[4]	See Note 3 for disclosure regarding impairments of long-lived assets.
[5]	See Note 3 for disclosure regarding impairments of long-lived assets.

Acquisitions, Mergers and Div_4

Acquisitions, Mergers and Divestitures - Schedule of Fair Value of Assets Acquired and Liabilities Assumed (Details) - USD ($) $ in Thousands		Sep. 30, 2019	Apr. 10, 2019	Nov. 13, 2017	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2019		Sep. 30, 2018	[3]	Dec. 31, 2018	Dec. 31, 2018
Fair value of assets acquired:
Goodwill	[1]	$ 962,218			$ 962,218		$ 962,218	$ 962,218				$ 1,123,813	$ 1,123,813
Impairment of goodwill					(261,300)								(261,300)
Measurement Period Adjustments
Decrease in amortization	[2]				(14,540)	$ (10,387)		(38,677)	[3]	$ (31,160)
EQM-RMP Merger
Consideration given:
Estimated fair value of RMP, EQM Olympus, Strike Force and EQM WV				$ 4,014,984
Fair value of liabilities assumed:
Current liabilities				(117,124)
Long-term debt				266,000
Other long-term liabilities				9,323
Fair value of assets acquired:
Current assets				132,459
Net property, plant and equipment				2,265,900
Intangible assets				623,200
Other assets				118
Noncontrolling interests				(166,000)
Goodwill		962,218		1,385,754	962,218		962,218	962,218				1,123,813	1,123,813
Total estimated fair value of assets acquired and liabilities assumed				$ 2,629,230
Impairment of goodwill								(161,595)				$ (261,900)	$ (261,941)
Bolt-on Acquisition
Consideration given:
Cash consideration		849,846	$ 861,250
Buyout of Eureka Midstream Class B Units and incentive compensation		2,530	2,530
Total consideration		852,376	863,780
Estimated fair value of RMP, EQM Olympus, Strike Force and EQM WV			1,040,000
Fair value of liabilities assumed:
Current liabilities		(42,601)	(52,458)		(42,601)		(42,601)	(42,601)
Long-term debt		300,825	300,825		300,825		300,825	300,825
Other long-term liabilities		10,203	10,203		10,203		10,203	10,203
Amount attributable to liabilities assumed		353,629	363,486		353,629		353,629	353,629
Fair value of assets acquired:
Cash		15,145	15,145		15,145		15,145	15,145
Accounts receivable		16,817	16,817		16,817		16,817	16,817
Inventory		12,965	12,991		12,965		12,965	12,965
Other current assets		882	882		882		882	882
Net property, plant and equipment		1,213,378	1,222,284		1,213,378		1,213,378	1,213,378
Intangible assets		311,000	317,000		311,000		311,000	311,000
Other assets		14,567	14,567		14,567		14,567	14,567
Amount attributable to assets acquired		1,584,754	1,599,686		1,584,754		1,584,754	1,584,754
Noncontrolling interests		(478,460)	(486,062)		(478,460)		(478,460)	(478,460)
Goodwill		0	$ 113,642		0		0	0
Goodwill		99,711			99,711		99,711	99,711
Impairment of goodwill					(99,711)
Measurement Period Adjustments
Consideration given							11,404
Current liabilities							(9,857)
Amount attributable to liabilities assumed							(9,857)
Inventory							(26)
Net property, plant and equipment							(8,906)
Intangible assets							6,000
Amount attributable to assets acquired							(14,932)
Noncontrolling interests							7,602
Goodwill purchase accounting adjustments							(13,931)
Decrease in amortization					(4,100)		400	(7,500)
RMP PA Gas Gathering Reporting Unit | EQM-RMP Merger
Fair value of assets acquired:
Goodwill		923,400			923,400		923,400	923,400
Rice Retained Midstream Reporting Unit | Bolt-on Acquisition
Fair value of assets acquired:
Goodwill		$ 38,800			$ 38,800		$ 38,800	$ 38,800
[1]	See Note 3 for disclosure regarding impairments of goodwill.
[2]	As discussed in Notes 1 and 2 , the consolidated financial statements of EQM have been retrospectively recast to include the pre-acquisition results of EQM Olympus Midstream LLC (EQM Olympus), Strike Force Midstream Holdings LLC (Strike Force) and EQM West Virginia Midstream LLC (EQM WV), which were acquired by EQM effective on May 1, 2018 (the Drop-Down Transaction), and RM Partners LP (RMP), which was acquired by EQM effective on July 23, 2018 (the EQM-RMP Merger), because these transactions were between entities under common control.
[3]	As discussed in Notes 1 and 2 , the consolidated financial statements of EQM have been retrospectively recast to include the pre-acquisition results of the Drop-Down Transaction and the EQM-RMP Merger because these transactions were between entities under common control.

Acquisitions, Mergers and Div_5

Acquisitions, Mergers and Divestitures - Schedule of Finite-Lived Intangible Assets Acquired as Part of Business Combination (Details) - Bolt-on Acquisition $ in Thousands	3 Months Ended
	Sep. 30, 2019USD ($)
Business Acquisition [Line Items]
Intangible assets	$ 311,000
Less: impairment of Hornet-related intangible assets	36,405
Less: accumulated amortization	7,517
Intangible assets, net	$ 267,078

Acquisitions, Mergers and Div_6

Acquisitions, Mergers and Divestitures - Schedule of Post-Acquisition Operating Results (Details) - USD ($) $ in Thousands	3 Months Ended				6 Months Ended	9 Months Ended
	Sep. 30, 2019	[1]	Sep. 30, 2018	[1]	Sep. 30, 2019	Sep. 30, 2019	[1]	Sep. 30, 2018	[1]
Business Acquisition [Line Items]
Net loss attributable to noncontrolling interests	$ (29,697)		$ 0		$ (25,664)	$ (25,664)		$ 3,346
Net loss attributable to EQM	$ (10,518)		$ 209,927		(87,949)	$ 393,851		$ 704,109
Bolt-on Acquisition
Business Acquisition [Line Items]
Operating revenues					61,579
Operating loss attributable to EQM					$ (109,277)
[1]	As discussed in Notes 1 and 2 , the consolidated financial statements of EQM have been retrospectively recast to include the pre-acquisition results of EQM Olympus Midstream LLC (EQM Olympus), Strike Force Midstream Holdings LLC (Strike Force) and EQM West Virginia Midstream LLC (EQM WV), which were acquired by EQM effective on May 1, 2018 (the Drop-Down Transaction), and RM Partners LP (RMP), which was acquired by EQM effective on July 23, 2018 (the EQM-RMP Merger), because these transactions were between entities under common control.

Acquisitions, Mergers and Div_7

Acquisitions, Mergers and Divestitures - Schedule of Unaudited Pro Forma Information (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended
	Mar. 31, 2019	Sep. 30, 2018	Sep. 30, 2018
Business Combinations [Abstract]
Pro forma operating revenues	$ 1,235,963	$ 391,151	$ 1,195,096
Pro forma net income	396,339	221,037	730,440
Pro forma net income attributable to noncontrolling interests	(22,447)	4,752	13,462
Pro forma net income attributable to EQM	$ 418,786	$ 216,285	$ 716,978
Pro forma income per limited partner common unit (basic) (USD per share)	$ 1.85	$ 0.95	$ 3.20
Pro forma income per limited partner common unit (diluted) (USD per share)	$ 1.78	$ 0.92	$ 3.09

Impairments of Long-Lived Ass_2

Impairments of Long-Lived Assets (Details) $ in Thousands		Apr. 25, 2018reporting_unit	Sep. 30, 2019USD ($)		Jun. 30, 2019USD ($)	Sep. 30, 2018USD ($)	[2],[3]	Sep. 30, 2019USD ($)reporting_unit		Sep. 30, 2018USD ($)	[2],[3],[4]	Dec. 31, 2018USD ($)	Dec. 31, 2018USD ($)	Apr. 10, 2019USD ($)	Nov. 13, 2017USD ($)
Business Acquisition [Line Items]
Number of reporting units | reporting_unit		2						3
Impairment of goodwill			$ 261,300										$ 261,300
Goodwill	[1]		962,218					$ 962,218				$ 1,123,813	1,123,813
Impairment of certain non-core natural gas pipeline assets			298,652	[2],[3]	$ 80,100	$ 0		378,787	[2],[3],[4]	$ 0
EQM-RMP Merger
Business Acquisition [Line Items]
Impairment of goodwill								161,595				261,900	261,941
Goodwill			962,218					962,218				$ 1,123,813	$ 1,123,813		$ 1,385,754
Bolt-on Acquisition
Business Acquisition [Line Items]
Impairment of goodwill			99,711
Goodwill			0					0						$ 113,642
Intangible asset impairment			36,405
RMP PA Gas Gathering Reporting Unit | EQM-RMP Merger
Business Acquisition [Line Items]
Goodwill			923,400					923,400
Rice Retained Midstream Reporting Unit | Bolt-on Acquisition
Business Acquisition [Line Items]
Goodwill			$ 38,800					$ 38,800
[1]	See Note 3 for disclosure regarding impairments of goodwill.
[2]	As discussed in Notes 1 and 2 , the consolidated financial statements of EQM have been retrospectively recast to include the pre-acquisition results of EQM Olympus Midstream LLC (EQM Olympus), Strike Force Midstream Holdings LLC (Strike Force) and EQM West Virginia Midstream LLC (EQM WV), which were acquired by EQM effective on May 1, 2018 (the Drop-Down Transaction), and RM Partners LP (RMP), which was acquired by EQM effective on July 23, 2018 (the EQM-RMP Merger), because these transactions were between entities under common control.
[3]	See Note 3 for disclosure regarding impairments of long-lived assets.
[4]	See Note 3 for disclosure regarding impairments of long-lived assets.

Leases - Narrative (Details)

Leases - Narrative (Details) $ in Thousands	Apr. 10, 2019USD ($)compressor_unit	Apr. 10, 2019USD ($)lease_agreement	Sep. 30, 2019USD ($)	Mar. 31, 2019USD ($)lease_agreement	Sep. 30, 2019USD ($)	Jan. 01, 2019USD ($)
Lessee, Lease, Description [Line Items]
Operating lease, right-of-use asset			$ 52,400		$ 52,400
Operating lease, liability			53,368		53,368
Operating lease cost			2,838		6,987
Cash paid for operating lease liabilities			2,500		6,300
Operating lease, liability, current			$ 10,100		$ 10,100
Weighted average remaining lease term			8 years		8 years
Weighted average discount rate			5.40%		5.40%
Accounting Standards Update 2016-02
Lessee, Lease, Description [Line Items]
Operating lease, right-of-use asset						$ 2,300
Operating lease, liability						$ 2,300
Shared Leases Assignment
Lessee, Lease, Description [Line Items]
Operating lease, right-of-use asset				$ 33,000
Operating lease, liability				$ 33,000
Number leases | lease_agreement				2
Disposal Group, Not Discontinued Operations | Copley Gathering System
Lessee, Lease, Description [Line Items]
Operating lease, right-of-use asset	$ 20,000	$ 20,000
Number leases	10	1
Operating lease cost			$ 1,700		$ 3,000
Bolt-on Acquisition
Lessee, Lease, Description [Line Items]
Operating lease, liability			$ 20,000		$ 20,000

Leases - Schedule of Operating

Leases - Schedule of Operating Lease Cost (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
	Sep. 30, 2019	Sep. 30, 2019
Leases [Abstract]
Operating lease cost	$ 2,838	$ 6,987
Short-term lease cost	1,473	3,353
Variable lease cost	100	112
Total lease cost	$ 4,411	$ 10,452

Leases - Schedule of Operatin_2

Leases - Schedule of Operating Lease Liability Maturities (Details) $ in Thousands	Sep. 30, 2019USD ($)
Leases [Abstract]
2019	$ 3,218
2020	12,168
2021	9,913
2022	7,694
2023	5,607
2024	3,966
Thereafter	24,728
Total	67,294
Less: imputed interest	13,926
Present value of operating lease liability	$ 53,368

Equity - Summary of Units Issue

Equity - Summary of Units Issued (Details) - shares	Feb. 13, 2019	Feb. 28, 2019	Sep. 30, 2019	Dec. 31, 2018
Increase (Decrease) in Partners' Capital
Balance at beginning (in shares)			121,900,653	82,024,773
Units issued in the period (in shares)			24,605,291	10,821
Unit cancellation (in shares)			(8)
EQM IDR Transaction (in shares)			85,556,985
Balance at end (in shares)			232,062,921	121,900,653
IDR Merger Agreement
Increase (Decrease) in Partners' Capital
Newly-issued common units (in shares)	80,000,000		80,000,000
Class B Units | IDR Merger Agreement
Increase (Decrease) in Partners' Capital
Newly-issued common units (in shares)	7,000,000	7,000,000	7,000,000
Drop Down Transaction
Increase (Decrease) in Partners' Capital
Units issued in Drop-Down and Merger transactions (in shares)				5,889,282
EQM-RMP Merger
Increase (Decrease) in Partners' Capital
Units issued in Drop-Down and Merger transactions (in shares)				33,975,777
Limited Partner Interests | Series A Preferred Units
Increase (Decrease) in Partners' Capital
Units issued in the period (in shares)			24,605,291
Balance at end (in shares)			24,605,291
Limited Partner Interests | Common Units
Increase (Decrease) in Partners' Capital
Balance at beginning (in shares)			120,457,638	80,581,758
Units issued in the period (in shares)				10,821
Unit cancellation (in shares)			(8)
EQM IDR Transaction (in shares)			80,000,000
Balance at end (in shares)			200,457,630	120,457,638
Limited Partner Interests | Class B Units
Increase (Decrease) in Partners' Capital
EQM IDR Transaction (in shares)			7,000,000
Balance at end (in shares)			7,000,000
Limited Partner Interests | Drop Down Transaction | Common Units
Increase (Decrease) in Partners' Capital
Units issued in Drop-Down and Merger transactions (in shares)				5,889,282
Limited Partner Interests | EQM-RMP Merger | Common Units
Increase (Decrease) in Partners' Capital
Units issued in Drop-Down and Merger transactions (in shares)				33,975,777
General Partner Units
Increase (Decrease) in Partners' Capital
Balance at beginning (in shares)			1,443,015	1,443,015
EQM IDR Transaction (in shares)			(1,443,015)
Balance at end (in shares)			0	1,443,015
General Partner Units | Common Units
Increase (Decrease) in Partners' Capital
EQM IDR Transaction (in shares)			87,000,000
Common Units
Increase (Decrease) in Partners' Capital
EQM IDR Transaction (in shares)			21,811,643
Common Units | EQM | EQGP
Increase (Decrease) in Partners' Capital
Partners' capital common units outstanding (in shares)	21,811,643		21,811,643

Equity - Narrative (Details)

Equity - Narrative (Details) $ / shares in Units, $ in Millions	Mar. 13, 2019USD ($)day$ / sharesshares	Feb. 13, 2019shares	Feb. 28, 2019shares	Sep. 30, 2019$ / sharesshares	Jun. 30, 2019$ / shares	Mar. 31, 2019$ / shares	Sep. 30, 2018$ / shares	Jun. 30, 2018$ / shares	Mar. 31, 2018$ / shares	Sep. 30, 2019shares	Dec. 31, 2018shares
Class of Stock [Line Items]
Distributions paid to unitholders (dollars per common unit) | $ / shares				$ 1,160	$ 1.145	$ 1.13	$ 1.09	$ 1.065	$ 1,025
Conversion basis	100.00%
Convertible units | $	$ 30
Threshold percentage of stock price trigger	140.00%
Threshold trading days | day	20
Threshold amount of stock price trigger (in shares)	500,000
Threshold consecutive trading days | day	20
Private Placement
Class of Stock [Line Items]
Aggregate number of units owned (in shares)	24,605,291
Cash purchase price for Series A Preferred Units (in dollars per share) | $ / shares	$ 48.77
Consideration received on transaction | $	$ 1,200
Distributions paid to unitholders (dollars per common unit) | $ / shares	$ 1.0364
Cumulative quarterly distribution increasing percentage (B)	1.725%
IDR Merger Agreement
Class of Stock [Line Items]
Common units received (in shares)		80,000,000								80,000,000
Units convertible as of April 1, 2021 (in shares)			2,500,000
Units convertible as of April 1, 2022 (in shares)			2,500,000
Units convertible as of April 1, 2023 (in shares)			2,000,000
Class B Units
Class of Stock [Line Items]
Common units outstanding (in shares)				7,000,000						7,000,000	0
Class B Units | IDR Merger Agreement
Class of Stock [Line Items]
Common units received (in shares)		7,000,000	7,000,000							7,000,000
ETRN | Class B Units
Class of Stock [Line Items]
Common units outstanding (in shares)				7,000,000						7,000,000
EQM | Private Placement
Class of Stock [Line Items]
Cash purchase price for Series A Preferred Units (in dollars per share) | $ / shares	$ 48.77
Cumulative quarterly distribution increasing percentage (A)	2.59%
Cumulative quarterly distribution increasing percentage (B)	6.90%
EQM | Public Ownership Interest
Class of Stock [Line Items]
Limited partner ownership interest										46.50%
EQM | Common Units | Equitrans Gathering Holdings, LLC
Class of Stock [Line Items]
Common units outstanding (in shares)				89,505,616						89,505,616
EQM | Common Units | Equitrans Gathering Holdings, LLC | Class B Units
Class of Stock [Line Items]
Common units outstanding (in shares)				6,153,907						6,153,907
EQM | Common Units | EQM GP Corporation
Class of Stock [Line Items]
Common units outstanding (in shares)				89,536						89,536
EQM | Common Units | EQM GP Corporation | Class B Units
Class of Stock [Line Items]
Common units outstanding (in shares)				6,155						6,155
EQM | Common Units | Equitrans Midstream Holdings, LLC
Class of Stock [Line Items]
Common units outstanding (in shares)				27,650,303						27,650,303
Limited partner ownership interest										53.50%
EQM | Common Units | Equitrans Midstream Holdings, LLC | Class B Units
Class of Stock [Line Items]
Common units outstanding (in shares)				839,938						839,938
EQM | Common Units | ETRN
Class of Stock [Line Items]
Common units outstanding (in shares)				117,245,455						117,245,455
Limited partner ownership interest										53.50%

Financial Information by Busi_3

Financial Information by Business Segment - Narrative (Details)	9 Months Ended
	Sep. 30, 2019business_linesegment
Segment Reporting [Abstract]
Number of business segments | segment	3
Number of lines of business | business_line	3

Financial Information by Busi_4

Financial Information by Business Segment - Schedule of Segment Information (Details) - USD ($) $ in Thousands		3 Months Ended												9 Months Ended
		Sep. 30, 2019		Jun. 30, 2019		Mar. 31, 2019	[6]	Sep. 30, 2018		Jun. 30, 2018		Mar. 31, 2018	[6]	Sep. 30, 2019		Sep. 30, 2018		Apr. 10, 2019	Dec. 31, 2018	Dec. 31, 2017
Revenues from customers:
Total operating revenues	[1],[2]	$ 408,434						$ 364,584						$ 1,204,383		$ 1,110,307
Operating (loss) income:
Total operating (loss) income	[1]	(31,077)						233,500						404,384		745,166
Reconciliation of operating (loss) income to net (loss) income:
Equity income	[1],[3]	44,448						16,087						112,293	[4]	35,836	[4]
Other income	[1]	337						1,345						4,506		3,193
Net interest expense	[1],[5]	53,923						41,005						152,996		76,740
Net (loss) income		(40,215)	[1],[6]	$ 156,471	[6]	$ 251,931		209,927	[1],[6]	$ 234,685	[6]	$ 262,843		368,187	[1],[4]	707,455	[1],[4]
Impairments of long-lived assets		298,652	[1],[7]	80,100				0	[1],[7]					378,787	[1],[7],[8]	0	[1],[7],[8]
Segment assets:
Total assets		12,154,037												12,154,037					$ 9,456,121
Depreciation:
Depreciation	[1]	59,197						43,567						162,777	[4]	126,957	[4]
Expenditures for segment assets:
Accrued capital expenditures		115,500		$ 110,800				91,300		$ 84,600				115,500		91,300		$ 8,800	108,900	$ 90,700
Operating Segments
Segment assets:
Total assets		11,949,781												11,949,781					9,315,915
Depreciation:
Depreciation		59,197						43,567						162,777		126,957
Expenditures for segment assets:
Expenditures for segment assets		301,900						240,084						822,830		616,947
Headquarters, including cash
Segment assets:
Total assets		204,256												204,256					140,206
Gathering
Revenues from customers:
Total operating revenues		299,491						252,861						847,038		731,440
Gathering | Operating Segments
Revenues from customers:
Total operating revenues		299,491						252,861						847,038		731,440
Operating (loss) income:
Total operating (loss) income		(98,489)						177,902						177,720		510,755
Reconciliation of operating (loss) income to net (loss) income:
Impairments of long-lived assets		298,700												378,800
Segment assets:
Total assets		7,949,204												7,949,204					6,011,654
Depreciation:
Depreciation		38,943						25,359						104,502		72,309
Expenditures for segment assets:
Expenditures for segment assets		272,138						194,477						745,053		515,072
Transmission
Revenues from customers:
Total operating revenues		87,299						89,350						289,926		285,429
Transmission | Operating Segments
Revenues from customers:
Total operating revenues		87,299						89,350						289,926		285,429
Operating (loss) income:
Total operating (loss) income		59,690						58,691						207,684		198,784
Segment assets:
Total assets		3,801,905												3,801,905					3,066,659
Depreciation:
Depreciation		13,347						12,357						38,474		37,228
Expenditures for segment assets:
Expenditures for segment assets		16,296						37,626						46,287		84,517
Water
Revenues from customers:
Total operating revenues		21,644						22,373						67,419		93,438
Water | Operating Segments
Revenues from customers:
Total operating revenues		21,644						22,373						67,419		93,438
Operating (loss) income:
Total operating (loss) income		7,722						(3,093)						18,980		35,627
Segment assets:
Total assets		198,672												198,672					$ 237,602
Depreciation:
Depreciation		6,907						5,851						19,801		17,420
Expenditures for segment assets:
Expenditures for segment assets		13,466						7,981						31,490		17,358
ETRN | Gathering | Operating Segments
Expenditures for segment assets:
Expenditures for segment assets		300												58,900
Eureka Midstream Holdings, LLC | Gathering | Operating Segments
Expenditures for segment assets:
Expenditures for segment assets		6,700												17,600
MVP Joint Venture | Transmission | Operating Segments
Expenditures for segment assets:
Expenditures for segment assets		$ 211,700						$ 263,200						$ 512,900		$ 446,000
[1]	As discussed in Notes 1 and 2 , the consolidated financial statements of EQM have been retrospectively recast to include the pre-acquisition results of EQM Olympus Midstream LLC (EQM Olympus), Strike Force Midstream Holdings LLC (Strike Force) and EQM West Virginia Midstream LLC (EQM WV), which were acquired by EQM effective on May 1, 2018 (the Drop-Down Transaction), and RM Partners LP (RMP), which was acquired by EQM effective on July 23, 2018 (the EQM-RMP Merger), because these transactions were between entities under common control.
[2]	Operating revenues included related party revenues from EQT Corporation (NYSE: EQT) (EQT) of $275.4 million and $276.9 million for the three months ended September 30, 2019 and 2018 , respectively, and $843.9 million and $827.8 million for the nine months ended September 30, 2019 and 2018 , respectively. See Note 8 .
[3]	Represents equity income from Mountain Valley Pipeline, LLC (the MVP Joint Venture). See Note 9 .
[4]	As discussed in Notes 1 and 2 , the consolidated financial statements of EQM have been retrospectively recast to include the pre-acquisition results of the Drop-Down Transaction and the EQM-RMP Merger because these transactions were between entities under common control.
[5]	Net interest expense included interest income on the Preferred Interest in EQT Energy Supply, LLC (EES), a subsidiary of EQT, of $1.6 million and $1.6 million for the three months ended September 30, 2019 and 2018 , respectively, and $4.8 million and $5.0 million for the nine months ended September 30, 2019 and 2018 , respectively.
[6]	As discussed in Notes 1 and 2 , the consolidated financial statements of EQM have been retrospectively recast to include the pre-acquisition results of the Drop-Down Transaction and the EQM-RMP Merger because these transactions were between entities under common control.
[7]	See Note 3 for disclosure regarding impairments of long-lived assets.
[8]	See Note 3 for disclosure regarding impairments of long-lived assets.

Revenue from Contracts with C_3

Revenue from Contracts with Customers - Schedule of Disaggregated Revenue Information, by Business Segment (Details) - USD ($) $ in Thousands		3 Months Ended		9 Months Ended
		Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Disaggregation of Revenue [Line Items]
Total operating revenues	[1],[2]	$ 408,434	$ 364,584	$ 1,204,383	$ 1,110,307
Firm reservation fee revenues
Disaggregation of Revenue [Line Items]
Total operating revenues		236,781	195,267	694,571	596,899
Volumetric-based fee revenues
Disaggregation of Revenue [Line Items]
Total operating revenues		150,009	146,944	442,393	419,970
Gathering
Disaggregation of Revenue [Line Items]
Total operating revenues		299,491	252,861	847,038	731,440
Gathering | Firm reservation fee revenues
Disaggregation of Revenue [Line Items]
Total operating revenues		154,791	112,598	431,520	334,233
Gathering | Volumetric-based fee revenues
Disaggregation of Revenue [Line Items]
Total operating revenues		144,700	140,263	415,518	397,207
Transmission
Disaggregation of Revenue [Line Items]
Total operating revenues		87,299	89,350	289,926	285,429
Transmission | Firm reservation fee revenues
Disaggregation of Revenue [Line Items]
Total operating revenues		81,990	82,669	263,051	262,666
Transmission | Volumetric-based fee revenues
Disaggregation of Revenue [Line Items]
Total operating revenues		5,309	6,681	26,875	22,763
Water
Disaggregation of Revenue [Line Items]
Total operating revenues		21,644	22,373	67,419	93,438
Water | Firm reservation fee revenues
Disaggregation of Revenue [Line Items]
Total operating revenues		0	0	0	0
Water | Volumetric-based fee revenues
Disaggregation of Revenue [Line Items]
Total operating revenues		$ 0	$ 0	$ 0	$ 0
[1]	As discussed in Notes 1 and 2 , the consolidated financial statements of EQM have been retrospectively recast to include the pre-acquisition results of EQM Olympus Midstream LLC (EQM Olympus), Strike Force Midstream Holdings LLC (Strike Force) and EQM West Virginia Midstream LLC (EQM WV), which were acquired by EQM effective on May 1, 2018 (the Drop-Down Transaction), and RM Partners LP (RMP), which was acquired by EQM effective on July 23, 2018 (the EQM-RMP Merger), because these transactions were between entities under common control.
[2]	Operating revenues included related party revenues from EQT Corporation (NYSE: EQT) (EQT) of $275.4 million and $276.9 million for the three months ended September 30, 2019 and 2018 , respectively, and $843.9 million and $827.8 million for the nine months ended September 30, 2019 and 2018 , respectively. See Note 8 .

Revenue from Contracts with C_4

Revenue from Contracts with Customers - Summary of Remaining Performance Obligations (Details) $ in Thousands	Sep. 30, 2019USD ($)
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2019-10-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Total	$ 258,929
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2020-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Total	994,419
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2021-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Total	1,114,383
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2022-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Total	1,115,112
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2023-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Total	1,074,977
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2024-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Total	5,510,585
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: (nil)
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Total	10,068,405
Transmission | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2019-10-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Total	$ 92,853
Remaining performance obligations, expected timing	3 months
Transmission | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2020-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Total	$ 348,324
Remaining performance obligations, expected timing	1 year
Transmission | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2021-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Total	$ 374,627
Remaining performance obligations, expected timing	1 year
Transmission | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2022-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Total	$ 370,617
Remaining performance obligations, expected timing	1 year
Transmission | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2023-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Total	$ 332,393
Remaining performance obligations, expected timing	1 year
Transmission | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2024-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Total	$ 2,731,561
Remaining performance obligations, expected timing
Transmission | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: (nil)
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Total	$ 4,250,375
Gathering firm reservation fees | Gathering | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2019-10-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Total	$ 124,735
Remaining performance obligations, expected timing	3 months
Gathering firm reservation fees | Gathering | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2020-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Total	$ 512,126
Remaining performance obligations, expected timing	1 year
Gathering firm reservation fees | Gathering | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2021-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Total	$ 586,691
Remaining performance obligations, expected timing	1 year
Gathering firm reservation fees | Gathering | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2022-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Total	$ 591,430
Remaining performance obligations, expected timing	1 year
Gathering firm reservation fees | Gathering | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2023-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Total	$ 590,342
Remaining performance obligations, expected timing	1 year
Gathering firm reservation fees | Gathering | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2024-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Total	$ 2,152,476
Remaining performance obligations, expected timing
Gathering firm reservation fees | Gathering | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: (nil)
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Total	$ 4,557,800
Minimum volume commitment contract | Gathering | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2019-10-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Total	$ 41,341
Remaining performance obligations, expected timing	3 months
Minimum volume commitment contract | Gathering | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2020-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Total	$ 133,969
Remaining performance obligations, expected timing	1 year
Minimum volume commitment contract | Gathering | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2021-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Total	$ 153,065
Remaining performance obligations, expected timing	1 year
Minimum volume commitment contract | Gathering | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2022-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Total	$ 153,065
Remaining performance obligations, expected timing	1 year
Minimum volume commitment contract | Gathering | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2023-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Total	$ 152,242
Remaining performance obligations, expected timing	1 year
Minimum volume commitment contract | Gathering | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2024-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Total	$ 626,548
Remaining performance obligations, expected timing
Minimum volume commitment contract | Gathering | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: (nil)
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Total	$ 1,260,230

Revenue from Contracts with C_5

Revenue from Contracts with Customers - Narrative (Details)	9 Months Ended
	Sep. 30, 2019
Gathering
Disaggregation of Revenue [Line Items]
Weighted average remaining term	11 years
Transmission
Disaggregation of Revenue [Line Items]
Weighted average remaining term	14 years

Related Party Transactions (Det

Related Party Transactions (Details)	Sep. 30, 2019
EQT | Equitrans Midstream Holdings, LLC
Related Party Transaction [Line Items]
Ownership interest	19.90%

Investment in Unconsolidated _3

Investment in Unconsolidated Entity - Narrative (Details) $ in Millions	1 Months Ended					9 Months Ended
	Dec. 31, 2019USD ($)	Nov. 30, 2019USD ($)	Oct. 31, 2019USD ($)	Sep. 30, 2019USD ($)mi	Aug. 31, 2019USD ($)	Sep. 30, 2019USD ($)mi	Oct. 01, 2019USD ($)	Feb. 28, 2019USD ($)	Jan. 31, 2019USD ($)	Apr. 30, 2018mi
MVP Joint Venture | Variable Interest Entity, Not Primary Beneficiary
Schedule of Equity Method Investments [Line Items]
Ownership interest				45.50%		45.50%
Maximum financial statement exposure				$ 2,191		$ 2,191
MVP Southgate Project | Variable Interest Entity, Not Primary Beneficiary
Schedule of Equity Method Investments [Line Items]
Ownership interest				47.20%		47.20%
Capital contribution payable to MVP Joint Venture					$ 6.2
MVP Project | Variable Interest Entity, Not Primary Beneficiary
Schedule of Equity Method Investments [Line Items]
Capital contribution payable to MVP Joint Venture				$ 254.9
MVP
Schedule of Equity Method Investments [Line Items]
Length of pipeline (in miles) | mi				300		300
MVP | Variable Interest Entity, Not Primary Beneficiary
Schedule of Equity Method Investments [Line Items]
Issuance of performance guarantee, remaining capital obligation, percentage								33.00%	33.00%
Issuance of performance guarantee									$ 261
MVP Southgate Project | EQM
Schedule of Equity Method Investments [Line Items]
Length of pipeline (in miles) | mi										70
MVP Southgate Project | Variable Interest Entity, Not Primary Beneficiary
Schedule of Equity Method Investments [Line Items]
Issuance of performance guarantee								$ 14
Beneficial Owner | MVP Joint Venture
Schedule of Equity Method Investments [Line Items]
Percentage of ownership interest						66.67%
Performance Guarantee | MVP | Variable Interest Entity, Not Primary Beneficiary
Schedule of Equity Method Investments [Line Items]
Performance guarantee				$ 211		$ 211
Subsequent Event | MVP Southgate Project | Variable Interest Entity, Not Primary Beneficiary
Schedule of Equity Method Investments [Line Items]
Capital call payments			$ 1.6
Subsequent Event | MVP Project | Variable Interest Entity, Not Primary Beneficiary
Schedule of Equity Method Investments [Line Items]
Capital call payments			$ 68.8
Subsequent Event | Performance Guarantee | MVP | Variable Interest Entity, Not Primary Beneficiary
Schedule of Equity Method Investments [Line Items]
Performance guarantee							$ 256
Scenario, Forecast | MVP Southgate Project | Variable Interest Entity, Not Primary Beneficiary
Schedule of Equity Method Investments [Line Items]
Capital call payments	$ 2.8	$ 1.8
Scenario, Forecast | MVP Project | Variable Interest Entity, Not Primary Beneficiary
Schedule of Equity Method Investments [Line Items]
Capital call payments	$ 62.2	$ 123.9

Investment in Unconsolidated _4

Investment in Unconsolidated Entity - Schedule of Unaudited Condensed Financial Statements for the Investment in Unconsolidated Equity (Details) - MVP Joint Venture - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018
Condensed Consolidated Balance Sheets
Current assets	$ 507,736		$ 507,736		$ 687,657
Non-current assets	4,735,119		4,735,119		3,223,220
Total assets	5,242,855		5,242,855		3,910,877
Current liabilities	468,011		468,011		617,355
Non-current liabilities	2,416		2,416		0
Equity	4,772,428		4,772,428		3,293,522
Total liabilities and equity	5,242,855		5,242,855		$ 3,910,877
Condensed Statements of Consolidated Operations
Environmental remediation reserve	(516)	$ 0	(2,682)	$ 0
Other income	1,165	1,923	5,863	3,200
Net interest income	29,100	10,036	73,035	22,674
AFUDC - equity	67,902	23,416	170,416	52,905
Net income	$ 97,651	$ 35,375	$ 246,632	$ 78,779

Debt - $3 Billion Facility (Det

Debt - $3 Billion Facility (Details)		3 Months Ended		9 Months Ended
		Sep. 30, 2019USD ($)	Sep. 30, 2018USD ($)	Sep. 30, 2019USD ($)	Sep. 30, 2018USD ($)	Dec. 31, 2018USD ($)	Oct. 31, 2018USD ($)
Debt Instrument [Line Items]
Consolidated leverage ratio for certain measurement periods (not more than)		5		5
Letters of credit outstanding	[1]	$ 557,500,000		$ 557,500,000		$ 625,000,000
$3 Billion Credit Facility | Revolving Credit Facility
Debt Instrument [Line Items]
Borrowings outstanding		265,000,000		265,000,000		625,000,000
Letters of credit outstanding		1,000,000		1,000,000		$ 1,000,000
$3 Billion Credit Facility | Line of credit
Debt Instrument [Line Items]
Maximum borrowing capacity		$ 3,000,000,000		3,000,000,000
Additional borrowing capacity				$ 750,000,000
Consolidated leverage ratio for certain measurement periods (not more than)		5		5
Consolidated leverage ratio (not more than)		5.50		5.50
Borrowings outstanding		$ 0		$ 0
Letters of credit outstanding		265,000,000		265,000,000
Maximum amount of outstanding short-term loans at any time during the period		1,700,000,000	$ 74,000,000		$ 420,000,000
Average daily balance of short-term loans outstanding		$ 865,000,000	$ 22,000,000	$ 950,000,000	$ 147,000,000
Weighted average annual interest rate		3.70%	3.70%	3.80%	3.20%
$3 Billion Credit Facility | Same-day swing line advances
Debt Instrument [Line Items]
Maximum borrowing capacity							$ 250,000,000
$3 Billion Credit Facility | Letter of credit
Debt Instrument [Line Items]
Maximum borrowing capacity		$ 400,000,000		$ 400,000,000
$1 Billion Credit Facility | Line of credit
Debt Instrument [Line Items]
Maximum borrowing capacity							$ 1,000,000,000
[1]	As of September 30, 2019 , EQM had credit facility borrowings outstanding of approximately $265 million and $293 million on its $3 Billion Facility and the Eureka Credit Facility, respectively (both defined herein). See Note 10 for further detail.

Debt - 2019 EQM Term Loan Facil

Debt - 2019 EQM Term Loan Facility (Details)	1 Months Ended	3 Months Ended		9 Months Ended
	Aug. 31, 2019USD ($)	Sep. 30, 2019USD ($)	Sep. 30, 2018USD ($)	Sep. 30, 2019USD ($)	Sep. 30, 2018	Jun. 30, 2018USD ($)
Debt Instrument [Line Items]
Consolidated leverage ratio for certain measurement periods (not more than)		5		5
Senior Notes
Debt Instrument [Line Items]
Net proceeds from offering			$ 2,465,800,000
Debt issuance costs						$ 22,400,000
Senior Notes | $1.4 Billion EQM Term Loan Facility
Debt Instrument [Line Items]
Aggregate principal amount	$ 1,400,000,000
Net proceeds from offering	1,397,400,000
Debt issuance costs	$ 2,600,000
Consolidated leverage ratio (not more than)		5.50		5.50
Line of Credit | $1.4 Billion EQM Term Loan Facility
Debt Instrument [Line Items]
Aggregate principal amount		$ 300,000,000		$ 300,000,000
Long-term debt		$ 1,400,000,000		1,400,000,000
Weighted average annual interest rate		3.60%
Line of Credit | $3 Billion Credit Facility
Debt Instrument [Line Items]
Maximum borrowing capacity		$ 3,000,000,000		3,000,000,000
Long-term debt		$ 0		$ 0
Weighted average annual interest rate		3.70%	3.70%	3.80%	3.20%
Consolidated leverage ratio for certain measurement periods (not more than)		5		5
Consolidated leverage ratio (not more than)		5.50		5.50

Debt - Eureka Credit Facility (

Debt - Eureka Credit Facility (Details) - Eureka Midstream, LLC - Line of credit - Eureka Credit Facility	Jun. 30, 2019USD ($)	Sep. 30, 2019USD ($)	Sep. 30, 2019USD ($)	Sep. 30, 2019USD ($)	Oct. 31, 2018USD ($)
Debt Instrument [Line Items]
Maximum borrowing capacity					$ 400,000,000
Additional borrowing capacity	$ 100,000,000
Available additional borrowings		$ 500,000,000	$ 500,000,000	$ 500,000,000
Consolidated leverage ratio		4.75	4.75	4.75
Maximum consolidated leverage ratio for certain measurement periods following certain acquisitions		5.25	5.25	5.25
Consolidated interest ratio		2.50	2.50	2.50
Borrowings outstanding		$ 293,000,000	$ 293,000,000	$ 293,000,000
Maximum amount of outstanding short-term loans at any time during the period		293,000,000	293,000,000
Average daily balance of short-term loans outstanding		$ 293,000,000	$ 285,000,000
Weighted average annual interest rate		4.30%	4.30%
Eurodollar
Debt Instrument [Line Items]
Basis spread on variable rate				1.00%
Eurodollar | Minimum
Debt Instrument [Line Items]
Basis spread on variable rate				1.75%
Eurodollar | Maximum
Debt Instrument [Line Items]
Basis spread on variable rate				3.00%
Federal Funds Effective Rate
Debt Instrument [Line Items]
Basis spread on variable rate				0.50%
Base Rate | Minimum
Debt Instrument [Line Items]
Basis spread on variable rate				0.75%
Base Rate | Maximum
Debt Instrument [Line Items]
Basis spread on variable rate				2.00%

Debt - EQM Term Loan Facility (

Debt - EQM Term Loan Facility (Details) - Line of credit - $2.5 Billion EQM Term Loan Facility - USD ($)	Apr. 25, 2018	Jun. 25, 2018	Jun. 25, 2018
Short-term Debt [Line Items]
Maximum borrowing capacity	$ 2,500,000,000
Maximum amount of outstanding short-term loans at any time during the period		$ 1,825,000,000
Line of credit expiration period	364 days
Write off of deferred issuance costs			$ 3,000,000
Average daily balance of short-term loans outstanding		$ 1,231,000,000
Weighted average annual interest rate		3.30%

Debt - RMP $850 Million Facilit

Debt - RMP $850 Million Facility (Details) - USD ($)		Jul. 23, 2018	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Debt Instrument [Line Items]
Repayment of borrowings outstanding	[1]			$ 2,227,000,000	$ 2,968,000,000
RMP $850 Million Facility | Line of credit
Debt Instrument [Line Items]
Maximum borrowing capacity				$ 850,000,000
Maximum amount of outstanding short-term loans at any time during the period			$ 260,000,000		375,000,000
Average daily balance of short-term loans outstanding			$ 249,000,000		$ 300,000,000
Weighted average annual interest rate			4.10%		3.80%
Repayment of borrowings outstanding		$ 260,000,000
[1]	As discussed in Notes 1 and 2 , the consolidated financial statements of EQM have been retrospectively recast to include the pre-acquisition results of the Drop-Down Transaction and the EQM-RMP Merger because these transactions were between entities under common control.

Debt - EQM 4.125% and 4.00% Sen

Debt - EQM 4.125% and 4.00% Senior Notes (Details) - USD ($)	Sep. 30, 2019	Dec. 31, 2016	Sep. 30, 2014
Senior Notes | EQM 4.125% Senior Notes due 2026
Debt Instrument [Line Items]
Interest rate (as a percent)	4.125%	4.125%
Aggregate principal amount		$ 500,000,000
Senior Notes | EQM 4.00 Senior Notes Due 2024
Debt Instrument [Line Items]
Interest rate (as a percent)	4.00%		4.00%
Aggregate principal amount			$ 500,000,000
Line of credit | $3 Billion Credit Facility
Debt Instrument [Line Items]
Maximum borrowing capacity	$ 3,000,000,000

Debt - 2018 Senior Notes (Detai

Debt - 2018 Senior Notes (Details) - USD ($)	3 Months Ended
	Sep. 30, 2018	Sep. 30, 2019	Jun. 30, 2018
Line of credit | RMP $850 Million Facility
Debt Instrument [Line Items]
Maximum borrowing capacity		$ 850,000,000
Senior Notes
Debt Instrument [Line Items]
Net proceeds from offering	$ 2,465,800,000
Discount			$ 11,800,000
Debt issuance costs			$ 22,400,000
Senior Notes | EQM 4.75% Senior Notes Due 2023
Debt Instrument [Line Items]
Interest rate (as a percent)			4.75%
Aggregate principal amount			$ 1,100,000,000
Senior Notes | EQM 5.50% Senior Notes Due 2028
Debt Instrument [Line Items]
Interest rate (as a percent)			5.50%
Aggregate principal amount			$ 850,000,000
Senior Notes | EQM 6.50% Senior Notes Due 2048
Debt Instrument [Line Items]
Interest rate (as a percent)			6.50%
Aggregate principal amount			$ 550,000,000

Fair Value Measurements (Detail

Fair Value Measurements (Details) - USD ($) $ in Millions	Sep. 30, 2019	Dec. 31, 2018
EES | Carrying Value
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Value of preferred interest	$ 111	$ 115
Level 3 | EES | Fair Value
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Value of preferred interest	128	122
Senior Notes | Fair Value, Measurements, Recurring | Level 2 | Fair Value
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Estimated fair value of long-term debt	3,439	3,425
Senior Notes | Fair Value, Measurements, Recurring | Level 2 | Carrying Value
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Estimated fair value of long-term debt	$ 3,461	$ 3,457

Net Income per Limited Partne_3

Net Income per Limited Partner Unit and Cash Distributions - Narrative (Details) - USD ($) $ / shares in Units, $ in Millions		Nov. 13, 2019	Oct. 21, 2019	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Distribution Made to Limited Partner [Line Items]
Cash distribution to the company's common and subordinated unitholders declared (in dollars per share)	[1],[2]			$ 1.160	$ 1.115	$ 3.465	$ 3.270
Phantom Share Units (PSUs)
Distribution Made to Limited Partner [Line Items]
Weighted average phantom unit awards included in the calculation of basic weighted average limited partner units outstanding (in shares)				25,305	17,816	23,687	19,699
Subsequent Event | Common Units
Distribution Made to Limited Partner [Line Items]
Cash distribution to the company's common and subordinated unitholders declared (in dollars per share)			$ 1.160
Subsequent Event | Series A Preferred Units
Distribution Made to Limited Partner [Line Items]
Cash distribution to the company's common and subordinated unitholders declared (in dollars per share)			$ 1.0364
Subsequent Event | Limited Partner Interests | Common Units
Distribution Made to Limited Partner [Line Items]
Cash distribution declared to the limited partner		$ 136
[1]	As discussed in Notes 1 and 2 , the consolidated financial statements of EQM have been retrospectively recast to include the pre-acquisition results of EQM Olympus Midstream LLC (EQM Olympus), Strike Force Midstream Holdings LLC (Strike Force) and EQM West Virginia Midstream LLC (EQM WV), which were acquired by EQM effective on May 1, 2018 (the Drop-Down Transaction), and RM Partners LP (RMP), which was acquired by EQM effective on July 23, 2018 (the EQM-RMP Merger), because these transactions were between entities under common control.
[2]	Represents the cash distributions declared related to the period presented. See Note 12 .

Net Income per Limited Partne_4

Net Income per Limited Partner Unit and Cash Distributions - Schedule of Net Income Per Limited Partner Unit (Details) - USD ($) $ / shares in Units, $ in Thousands		3 Months Ended				6 Months Ended	9 Months Ended
		Sep. 30, 2019		Sep. 30, 2018		Sep. 30, 2019	Sep. 30, 2019		Sep. 30, 2018
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Net (loss) income attributable to EQM		$ (10,518)	[1]	$ 209,927	[1]	$ (87,949)	$ 393,851	[1]	$ 704,109	[1]
Less: Series A Preferred Units interest in net income	[1]	(25,501)		0			(48,480)		0
Less: pre-acquisition net income allocated to EQT	[1]	0		(8,490)			0		(164,242)
Less: general partner interest in net income – general partner units	[1]	0		(2,379)			0		(7,145)
Less: general partner interest in net income – IDRs	[1]	0		(70,967)			0		(183,253)
Limited partner interest in net income	[1]	$ (36,019)		$ 128,091			$ 345,371		$ 349,469
Weighted average limited partner common units outstanding – basic (in shares)	[1]	200,483,000		111,980,000			185,244,000		93,746,000
Weighted average limited partner common units outstanding – diluted (in shares)	[1]	200,483,000		111,980,000			192,244,000		93,746,000
Net (loss) income per limited partner common unit – basic (in dollars per share)	[1],[2]	$ (0.18)		$ 1.14			$ 1.86		$ 3.73
Net (loss) income per limited partner common unit – diluted (in dollars per share)	[1],[2]	$ (0.18)		$ 1.14			$ 1.80		$ 3.73
Common Units
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Limited partner interest in net income		$ (36,019)		$ 128,091			$ 345,371		$ 349,469
Class B Units
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Limited partner interest in net income		$ 0		$ 0			$ 0		$ 0
Units included in the calculation of diluted weighted average limited partner units outstanding (in shares)		7,000,000					7,000,000
Series A Preferred Units
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Units included in the calculation of diluted weighted average limited partner units outstanding (in shares)		24,605,291
[1]	As discussed in Notes 1 and 2 , the consolidated financial statements of EQM have been retrospectively recast to include the pre-acquisition results of EQM Olympus Midstream LLC (EQM Olympus), Strike Force Midstream Holdings LLC (Strike Force) and EQM West Virginia Midstream LLC (EQM WV), which were acquired by EQM effective on May 1, 2018 (the Drop-Down Transaction), and RM Partners LP (RMP), which was acquired by EQM effective on July 23, 2018 (the EQM-RMP Merger), because these transactions were between entities under common control.
[2]	See Note 12 for disclosure regarding EQM's calculation of net income per limited partner unit (basic and diluted).