Transactions with Affiliates - Equipment Purchases and Sales Table (Details) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Related Party Transaction [Line Items]
Partners’ capital adjustment	[1]	$ (3,189)	$ 581	$ 4,632
Western Gas Partners, LP [Member] | Affiliates [Member] | Purchases [Member]
Related Party Transaction [Line Items]
Cash consideration - purchases		3,910	3,965	10,903
Net carrying value		(5,283)	(3,366)	(6,318)
Partners’ capital adjustment		(1,373)	599	4,585
Western Gas Partners, LP [Member] | Affiliates [Member] | Sales [Member]
Related Party Transaction [Line Items]
Cash consideration - sales		0	623	925
Net carrying value		0	(605)	(972)
Partners’ capital adjustment		$ 0	$ (18)	$ 47

[1] Includes $(1.4) million related to pipe and equipment purchases and $(1.8) million related to other assets for the year ended December 31, 2017. See Note 5.