Partnership Distributions - Cash Distributions Tables (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018
Distribution Made to Limited Partner [Line Items]
Total quarterly per-unit distribution	$ 0.31100	$ 0.31100	$ 0.31100	$ 0.31100	$ 0.62200	$ 0.62000	$ 0.61800	$ 0.61000	$ 0.60250	$ 0.59500	$ 0.58250	$ 0.56875
Total quarterly cash distribution	$ 131,265	$ 132,255	$ 140,900	$ 140,893	$ 281,786	$ 280,880	$ 279,959	$ 276,324	$ 131,910	$ 130,268	$ 127,531	$ 124,518
WES Operating [Member]
Distribution Made to Limited Partner [Line Items]
Total quarterly per-unit distribution									$ 0.980	$ 0.965	$ 0.950	$ 0.935
Total quarterly cash distribution	$ 127,470	$ 143,404	$ 143,404	$ 143,404	$ 290,314	$ 289,676	$ 288,083	$ 283,271	$ 234,787	$ 230,239	$ 225,691	$ 221,133