Consolidated Statements of Equity and Partners' Capital - USD ($) $ in Thousands		Total	Chipeta [Member]	WES Operating [Member]	Net Investment by Anadarko [Member]	Common Units [Member]	Noncontrolling Interests [Member]	Noncontrolling Interests [Member] Chipeta [Member]	Noncontrolling Interests [Member] WES Operating [Member]
Balance at Dec. 31, 2017	[1]	$ 4,995,050			$ 1,050,171	$ 1,061,125	$ 2,883,754
Increase (Decrease) in Partners' Capital [Roll Forward]
Net income (loss)	[1]	181,010			30,522	101,005	49,483
Above-market component of swap agreements with Anadarko	[1],[2]	14,282				14,282
WES Operating equity transactions, net	[1],[3]	0				(2,525)	2,525
Distributions to noncontrolling interest owners	[1]		$ (3,353)	$ (94,272)				$ (3,353)	$ (94,272)
Distributions to Partnership unitholders	[1]	(120,140)				(120,140)
Contributions of equity-based compensation from Anadarko/Occidental	[1]	1,470				1,470
Net pre-acquisition contributions from (distributions to) Anadarko	[1]	64,251			64,251
Adjustments of net deferred tax liabilities	[1]	(175)			(175)
Other	[1]	150				58	92
Balance at Mar. 31, 2018	[1]	4,994,493			1,145,398	1,041,066	2,808,029
Balance at Dec. 31, 2017	[1]	4,995,050			1,050,171	1,061,125	2,883,754
Increase (Decrease) in Partners' Capital [Roll Forward]
Net income (loss)	[1]	446,737
Net contributions from (distributions to) Anadarko of other assets	[1]	58,835
Balance at Sep. 30, 2018	[1]	4,989,843			1,373,203	981,408	2,635,232
Increase (Decrease) in Partners' Capital [Roll Forward]
Cumulative effect of accounting change	[1]	(43,780)			629	(14,209)	(30,200)
Balance at Mar. 31, 2018	[1]	4,994,493			1,145,398	1,041,066	2,808,029
Increase (Decrease) in Partners' Capital [Roll Forward]
Net income (loss)	[1]	67,167			32,604	67,580	(33,017)
Above-market component of swap agreements with Anadarko	[1],[2]	13,839				13,839
WES Operating equity transactions, net	[1],[3]	0				(4,965)	4,965
Distributions to noncontrolling interest owners	[1]		(3,068)	(95,809)				(3,068)	(95,809)
Distributions to Partnership unitholders	[1]	(124,518)				(124,518)
Contributions of equity-based compensation from Anadarko/Occidental	[1]	1,331				1,331
Net pre-acquisition contributions from (distributions to) Anadarko	[1]	93,013			93,013
Other	[1]	192				76	116
Balance at Jun. 30, 2018	[1]	4,946,670			1,271,015	994,418	2,681,237
Increase (Decrease) in Partners' Capital [Roll Forward]
Cumulative effect of accounting change	[1]	30				9	21
Net income (loss)	[1]	198,560			43,883	107,474	47,203
Above-market component of swap agreements with Anadarko	[1],[2]	12,601				12,601
WES Operating equity transactions, net	[1],[3]	0				(7,075)	7,075
Distributions to noncontrolling interest owners	[1]		(3,025)	(97,354)				(3,025)	(97,354)
Distributions to Partnership unitholders	[1]	(127,531)				(127,531)
Contributions of equity-based compensation from Anadarko/Occidental	[1]	1,505				1,505
Net pre-acquisition contributions from (distributions to) Anadarko	[1]	(530)			(530)
Net contributions from (distributions to) Anadarko of other assets	[1]	58,835			58,835
Other	[1]	112				16	96
Balance at Sep. 30, 2018	[1]	4,989,843			1,373,203	981,408	2,635,232
Balance at Dec. 31, 2018	[1]	4,892,683			1,388,018	951,888	2,552,777
Increase (Decrease) in Partners' Capital [Roll Forward]
Net income (loss)		211,979			29,116	89,544	93,319
Cumulative impact of the Merger transactions	[4]	0				3,169,800	(3,169,800)
Above-market component of swap agreements with Anadarko	[5]	7,407				7,407
WES Operating equity transactions, net	[6]	0				(752,796)	752,796
Distributions to noncontrolling interest owners			(1,935)	(100,999)				(1,935)	(100,999)
Distributions to Partnership unitholders		(131,910)				(131,910)
Acquisitions from affiliates	[7]	(2,007,501)			(2,141,827)	106,856	27,470
Contributions of equity-based compensation from Anadarko/Occidental		1,840				1,840
Net pre-acquisition contributions from (distributions to) Anadarko		451,591			451,591
Adjustments of net deferred tax liabilities		268,727			273,102	(4,375)
Other		(341)				(332)	(9)
Balance at Mar. 31, 2019		3,591,541			0	3,437,922	153,619
Balance at Dec. 31, 2018	[1]	4,892,683			1,388,018	951,888	2,552,777
Increase (Decrease) in Partners' Capital [Roll Forward]
Net income (loss)		512,260
Net contributions from (distributions to) Anadarko of other assets		0
Balance at Sep. 30, 2019		3,335,075			0	3,182,917	152,158
Balance at Mar. 31, 2019		3,591,541			0	3,437,922	153,619
Increase (Decrease) in Partners' Capital [Roll Forward]
Net income (loss)		175,058			163	169,431	5,464
Distributions to noncontrolling interest owners			(1,858)	(5,667)				(1,858)	(5,667)
Distributions to Partnership unitholders		(276,324)				(276,324)
Acquisitions from affiliates	[7]	0			(5,510)	4,493	1,017
Contributions of equity-based compensation from Anadarko/Occidental		2,768				2,768
Net pre-acquisition contributions from (distributions to) Anadarko		5,347			5,347
Other		345				356	(11)
Balance at Jun. 30, 2019		3,491,210			0	3,338,646	152,564
Increase (Decrease) in Partners' Capital [Roll Forward]
Net income (loss)		125,223				121,217	4,006
WES Operating equity transactions, net	[6]	0				(2,401)	2,401
Distributions to noncontrolling interest owners			$ (1,407)	$ (5,764)				$ (1,407)	$ (5,764)
Distributions to Partnership unitholders		(279,959)				(279,959)
Acquisitions from affiliates	[7]	0			(1,881)	1,523	358
Contributions of equity-based compensation from Anadarko/Occidental		3,355				3,355
Net pre-acquisition contributions from (distributions to) Anadarko		1,881			1,881
Other		536				536
Balance at Sep. 30, 2019		$ 3,335,075			$ 0	$ 3,182,917	$ 152,158

[1] Financial information has been recast to include the financial position and results attributable to AMA. See Note 1 and Note 3.

[2] See Note 6.

[3] For the three months ended March 31, 2018, June 30, 2018, and September 30, 2018, the $2.5 million, $5.0 million, and $7.1 million decrease to partners’ capital, respectively, together with net income (loss) attributable to Western Midstream Partners, LP, totaled $129.0 million, $95.2 million, and $144.3 million, respectively.

[4] See Note 1.

[5] See Note 6.

[6] For the three months ended March 31, 2019, and September 30, 2019, the $752.8 million and $2.4 million decrease to partners’ capital, respectively, together with net income (loss) attributable to Western Midstream Partners, LP, totaled $(634.1) million and $118.8 million, respectively.

[7] The amounts allocated to common unitholders and noncontrolling interests represent a noncash investing activity related to the assets and liabilities assumed in the AMA acquisition.