Transactions with Affiliates - Omnibus Agreement Tables (Details) - Omnibus Agreement [Member] - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Related Party Transaction [Line Items]
Allocated costs from Anadarko	$ 2,084	$ 2,707	$ 2,253
Western Gas Partners, LP [Member]
Related Party Transaction [Line Items]
Allocated costs from Anadarko	41,112	37,770	31,846
General and Administrative Expenses [Member]
Related Party Transaction [Line Items]
Allocated costs from Anadarko	263	258	256
General and Administrative Expenses [Member] | Western Gas Partners, LP [Member]
Related Party Transaction [Line Items]
Allocated costs from Anadarko	31,733	29,360	22,896
Public Company Expenses [Member]
Related Party Transaction [Line Items]
Allocated costs from Anadarko	1,821	2,449	1,997
Public Company Expenses [Member] | Western Gas Partners, LP [Member]
Related Party Transaction [Line Items]
Allocated costs from Anadarko	$ 9,379	$ 8,410	$ 8,950