Partnership Distributions - Cash Distributions Tables (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 31, 2019		Dec. 31, 2018		Sep. 30, 2018		Jun. 30, 2018		Mar. 31, 2018
Distribution Made to Limited Partner [Line Items]
Total quarterly distribution per unit	$ 0.61000	[1]	$ 0.60250	[2]	$ 0.59500	[2]	$ 0.58250	[2]	$ 0.56875	[2]
Total quarterly cash distribution	$ 276,324	[1]	$ 131,910	[2]	$ 130,268	[2]	$ 127,531	[2]	$ 124,518	[2]
WES Operating [Member]
Distribution Made to Limited Partner [Line Items]
Total quarterly distribution per unit			$ 0.980		$ 0.965		$ 0.950		$ 0.935
Total quarterly cash distribution	$ 283,300		$ 234,787		$ 230,239		$ 225,691		$ 221,133

[1] The Board of Directors declared a cash distribution to the Partnership’s unitholders for the first quarter of 2019 of $0.61000 per unit, or $276.3 million in aggregate. The cash distribution is payable on May 14, 2019, to unitholders of record at the close of business on May 1, 2019.

[2] The 2018 distributions were declared and paid prior to the closing of the Merger.