Partnership Distributions - Cash Distributions Tables (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Dec. 31, 2017		Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015
Distribution Made to Limited Partner [Line Items]
Total quarterly distribution per unit	$ 0.54875	[1]	$ 0.53750	$ 0.52750	$ 0.49125	$ 0.46250	$ 0.44750	$ 0.43375	$ 0.42375	$ 0.40375	$ 0.38125	$ 0.36375	$ 0.34250
Total quarterly cash distribution	$ 120,140	[1]	$ 117,677	$ 115,487	$ 107,549	$ 101,254	$ 97,968	$ 94,958	$ 92,767	$ 88,389	$ 83,461	$ 79,630	$ 74,977
Western Gas Partners, LP [Member]
Distribution Made to Limited Partner [Line Items]
Total quarterly distribution per unit	$ 0.920	[2]	$ 0.905	$ 0.890	$ 0.875	$ 0.860	$ 0.845	$ 0.830	$ 0.815	$ 0.800	$ 0.775	$ 0.750	$ 0.725
Total quarterly cash distribution	$ 216,586	[2]	$ 212,038	$ 207,491	$ 188,753	$ 170,657	$ 166,742	$ 162,827	$ 158,905	$ 152,588	$ 146,160	$ 139,736	$ 133,203

[1] The Board of Directors declared a cash distribution to WGP unitholders for the fourth quarter of 2017 of $0.54875 per unit, or $120.1 million in aggregate. The cash distribution is payable on February 22, 2018, to WGP unitholders of record at the close of business on February 1, 2018.

[2] The Board of Directors of WES GP declared a cash distribution to WES unitholders for the fourth quarter of 2017 of $0.920 per unit, or $216.6 million in aggregate, including incentive distributions, but excluding distributions on WES Class C units (see WES Class C unit distributions below). The cash distribution was paid on February 13, 2018, to WES unitholders of record at the close of business on February 1, 2018.