Partnership Distributions - Cash Distributions Tables (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Jun. 30, 2015		Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014
Distribution Made to Limited Partner [Line Items]
Total quarterly distribution per unit	$ 0.36375	[1]	$ 0.342500	$ 0.31250	$ 0.29125	$ 0.27125	$ 0.25000
Total quarterly cash distribution	$ 79,630	[1]	$ 74,977	$ 68,409	$ 63,756	$ 59,378	$ 54,726
Western Gas Partners, LP [Member]
Distribution Made to Limited Partner [Line Items]
Total quarterly distribution per unit	$ 0.750	[2]	$ 0.725	$ 0.700	$ 0.675	$ 0.650	$ 0.625
Total quarterly cash distribution	$ 139,736	[2]	$ 133,203	$ 126,044	$ 111,608	$ 105,655	$ 98,749

[1] On July 16, 2015, the Board of Directors of WGP GP declared a cash distribution to WGP unitholders of $0.36375 per unit, or $79.6 million in aggregate. The cash distribution is payable on August 21, 2015, to WGP unitholders of record at the close of business on July 31, 2015.

[2] On July 16, 2015, the Board of Directors of WES GP declared a cash distribution to WES unitholders of $0.750 per unit, or $139.7 million in aggregate, including incentive distributions, but excluding distributions on WES Class C units (see WES Class C unit distributions below). The cash distribution is payable on August 12, 2015, to WES unitholders of record at the close of business on July 31, 2015.