Debt and Interest Expense - Interest Expense Table (Details) - USD ($) $ in Thousands		3 Months Ended		9 Months Ended
		Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Debt Instrument [Line Items]
Interest expense	[1]	$ (36,117)	$ (31,301)	$ (108,447)	$ (76,869)
Third Parties [Member]
Debt Instrument [Line Items]
Long-term debt		(36,223)	(31,795)	(106,412)	(88,123)
Amortization of debt issuance costs and commitment fees		(2,009)	(2,022)	(5,955)	(5,517)
Capitalized interest		2,115	1,343	3,991	4,674
Interest expense		(36,117)	(32,474)	(108,376)	(88,966)
Affiliates [Member]
Debt Instrument [Line Items]
Interest expense	[2]	0	1,173	(71)	12,097
Affiliates [Member] | Deferred Purchase Price Obligation - Anadarko [Member]
Debt Instrument [Line Items]
Deferred purchase price obligation - Anadarko	[3]	$ 0	$ 1,173	$ (71)	$ 12,097

[1] Includes affiliate (as defined in Note 1) amounts of zero and $(0.1) million for the three and nine months ended September 30, 2017, respectively, and $1.2 million and $12.1 million for the three and nine months ended September 30, 2016, respectively. See Note 2 and Note 9.

[2] Includes amounts related to WES’s Deferred purchase price obligation - Anadarko (see Note 2 and Note 9).

[3] See Note 2 for a discussion of the Deferred purchase price obligation - Anadarko.