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Acquisitions and Divestitures - Additional Information (Details) - USD ($) $ in Millions			3 Months Ended		12 Months Ended
	Feb. 28, 2019	Jan. 18, 2019	Jun. 30, 2021	Dec. 31, 2020	Dec. 31, 2021	Oct. 09, 2020
Property, Plant and Equipment [Line Items]
Limited partner units				413,839,863	402,993,919
WES Operating [Member]
Property, Plant and Equipment [Line Items]
Limited partner units				318,675,578	318,675,578
Mi Vida [Member]
Property, Plant and Equipment [Line Items]
Ownership percentage acquired	50.00%
Ranch Westex [Member]
Property, Plant and Equipment [Line Items]
Ownership percentage acquired	50.00%
Saddlehorn [Member]
Property, Plant and Equipment [Line Items]
Ownership percentage acquired	20.00%
Panola [Member]
Property, Plant and Equipment [Line Items]
Ownership percentage acquired	15.00%
Anadarko Midstream Assets [Member] \| WES Operating [Member] \| Anadarko [Member]
Property, Plant and Equipment [Line Items]
Cash payment for acquisition	$ 2,000.0
Anadarko Midstream Assets [Member] \| Common Units [Member] \| WES Operating [Member]
Property, Plant and Equipment [Line Items]
Units issued	45,760,201
Anadarko Midstream Assets [Member] \| Common Units [Member] \| Anadarko [Member] \| WES Operating [Member]
Property, Plant and Equipment [Line Items]
Limited partner units	6,375,284
Red Bluff Express [Member]
Property, Plant and Equipment [Line Items]
Ownership percentage acquired		30.00%
Acquisition, net investment		$ 92.5
Fort Union [Member]
Property, Plant and Equipment [Line Items]
Equity-investment ownership percentage						14.81%
Net gain on sale of assets				$ 21.0
Fort Union and Bison Treating Facility [Member]
Property, Plant and Equipment [Line Items]
Proceeds from sale of assets				27.0
Bison [Member]
Property, Plant and Equipment [Line Items]
Proceeds from sale of assets			$ 1.0	$ 7.0	$ 8.0
Net gain on sale of assets					$ 5.4