Partnership Distributions - Additional Information (Details) - USD ($) $ / shares in Units, $ in Thousands				3 Months Ended												12 Months Ended
	Feb. 28, 2019	May 02, 2017	Mar. 01, 2017	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2019
Distribution Made to Limited Partner [Line Items]
Partnership agreement day requirement of distribution of available cash																55 days
Common units outstanding				443,971,409				218,937,797								443,971,409
Total quarterly cash distribution				$ 281,786	$ 280,880	$ 279,959	$ 276,324	$ 131,910	$ 130,268	$ 127,531	$ 124,518	$ 120,140	$ 117,677	$ 115,487	$ 107,549
WES [Member]
Distribution Made to Limited Partner [Line Items]
Incentive distributions percentage	48.00%
WES [Member] | Common Units [Member]
Distribution Made to Limited Partner [Line Items]
Common units outstanding	452,990,862							218,937,797
WES Operating [Member]
Distribution Made to Limited Partner [Line Items]
Total quarterly cash distribution				$ 290,300	$ 289,700	$ 288,100	$ 283,300	$ 234,787	$ 230,239	$ 225,691	$ 221,133	$ 216,586	$ 212,038	$ 207,491	$ 188,753
WES Operating [Member] | Common Units [Member]
Distribution Made to Limited Partner [Line Items]
Common units outstanding	152,609,285
WES Operating [Member] | Class C Units [Member]
Distribution Made to Limited Partner [Line Items]
Common units outstanding	14,681,388
Class C units, discount rate percentage on distribution	6.00%
Class C units, common units issued upon conversion	1
WES Operating [Member] | Series A Preferred Units [Member]
Distribution Made to Limited Partner [Line Items]
Series A Preferred units, distribution per unit															$ 0.68
Series A Preferred units, cash distribution															$ 7,500
WES Operating [Member] | Series A Preferred Units [Member] | Series A Preferred Units March 2017 Conversion [Member]
Distribution Made to Limited Partner [Line Items]
Series A Preferred units, percentage converted			50.00%
Series A Preferred units, common units issued upon conversion			1
WES Operating [Member] | Series A Preferred Units [Member] | Series A Preferred Units May 2017 Conversion [Member]
Distribution Made to Limited Partner [Line Items]
Series A Preferred units, percentage converted		50.00%
Series A Preferred units, common units issued upon conversion		1
WES Operating [Member] | WES [Member]
Distribution Made to Limited Partner [Line Items]
Distribution sharing percentage	1.50%
WES Operating [Member] | WES [Member] | Common Units [Member]
Distribution Made to Limited Partner [Line Items]
Common units outstanding	50,132,046
WES Operating [Member] | Anadarko [Member] | Common Units [Member]
Distribution Made to Limited Partner [Line Items]
Common units outstanding				6,400,000												6,400,000
WES [Member] | Occidental [Member]
Distribution Made to Limited Partner [Line Items]
Common units outstanding				242,136,976												242,136,976
Distribution sharing percentage				2.00%
WES [Member] | Occidental [Member] | Common Units [Member]
Distribution Made to Limited Partner [Line Items]
Common units outstanding				9,060,641												9,060,641