Consolidated Statements of Equity and Partners' Capital - WES Operating - USD ($) $ in Thousands		Total		Chipeta [Member]	Net Investment by Anadarko [Member]		Common Units [Member]		Noncontrolling Interest [Member]		Noncontrolling Interest [Member] Chipeta [Member]	WES Operating [Member]		WES Operating [Member] Chipeta [Member]	WES Operating [Member] Net Investment by Anadarko [Member]		WES Operating [Member] Common Units [Member]		WES Operating [Member] Class C Units [Member]		WES Operating [Member] General Partner [Member]		WES Operating [Member] Noncontrolling Interest [Member]	WES Operating [Member] Noncontrolling Interest [Member] Chipeta [Member]
Balance at Dec. 31, 2017	[1]	$ 4,995,050			$ 1,050,171		$ 1,061,125		$ 2,883,754			$ 5,021,182			$ 1,050,171		$ 2,950,010		$ 780,040		$ 179,232		$ 61,729
Increase (Decrease) in Partners' Capital [Roll Forward]
Net income (loss)	[1]	181,010			30,522		101,005		49,483			182,870			30,522		59,133		6,791		83,439		2,985
Above-market component of swap agreements with Anadarko	[1]	14,282	[2]				14,282	[2]				14,282	[3]				14,282	[3]
Amortization of beneficial conversion feature of Class C units	[1]											0					(810)		810
Distributions to noncontrolling interest owners	[1]			$ (3,353)							$ (3,353)			$ (3,353)										$ (3,353)
Distributions to WES Operating unitholders	[1]	(120,140)					(120,140)					(216,586)					(140,394)				(76,192)
Contributions of equity-based compensation from Anadarko	[1]	1,470					1,470					1,464					1,435				29
Net pre-acquisition contributions from (distributions to) Anadarko	[1]	64,251			64,251							64,251			64,251
Adjustments of net deferred tax liabilities	[1]	(175)			(175)							(175)			(175)
Other	[1]	150					58		92			91					91
Balance at Mar. 31, 2018	[1]	4,994,493			1,145,398		1,041,066		2,808,029			5,020,246			1,145,398		2,842,612		784,105		185,812		62,319
Increase (Decrease) in Partners' Capital [Roll Forward]
Cumulative effect of accounting change	[1]	(43,780)			629		(14,209)		(30,200)			(43,780)			629		(41,135)		(3,536)		(696)		958
Balance at Dec. 31, 2018	[1]	4,892,683			1,388,018		951,888		2,552,777			4,919,597			1,388,018		2,475,540		791,410		206,862		57,767
Increase (Decrease) in Partners' Capital [Roll Forward]
Net income (loss)		211,979			29,116		89,544		93,319			214,450			29,116		170,847		10,636		1,997		1,854
Cumulative impact of the Merger transactions		0	[4]				3,169,800	[4]	(3,169,800)	[4]		0	[5]				926,236	[5]	(802,588)	[5]	(123,648)	[5]
Above-market component of swap agreements with Anadarko		7,407	[6]				7,407	[6]				7,407	[7]				7,407	[7]
Amortization of beneficial conversion feature of Class C units												0					(542)		542
Distributions to noncontrolling interest owners				$ (1,935)							$ (1,935)			$ (1,935)										$ (1,935)
Distributions to WES Operating unitholders		(131,910)					(131,910)					(263,358)					(178,128)				(85,230)
Acquisitions from affiliates		(2,007,501)	[8]		(2,141,827)	[8]	106,856	[8]	27,470	[8]		(2,007,501)	[9]		(2,141,827)	[9]	134,326	[9]
Contributions of equity-based compensation from Anadarko		1,840					1,840					1,838					1,819				19
Net pre-acquisition contributions from (distributions to) Anadarko		451,591			451,591							451,591			451,591
Adjustments of net deferred tax liabilities		268,727			273,102		(4,375)					268,727			273,102		(4,375)
Other		(341)					(332)		(9)			268					268
Balance at Mar. 31, 2019		$ 3,591,541			$ 0		$ 3,437,922		$ 153,619			$ 3,591,084			$ 0		$ 3,533,398		$ 0		$ 0		$ 57,686

[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] See Note 6.

[4] See Note 1.

[5] See Note 1.

[6] See Note 6.

[7] See Note 6.

[8] 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.

[9] The amount allocated to common unitholders represents a noncash investing activity related to the assets and liabilities assumed in the AMA acquisition.