Cash Flows (Details) - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Supplemental Cash Flow Elements [Abstract]
Income taxes paid	$ 456	$ 1	$ 0
Interest paid, excluding amounts capitalized	13,411	1,837	0
Contribution of net assets from affiliate	$ 133,259	$ 60,870	$ 146,513
Contribution of common units to Western	10,000	40,000	0
Accrued TexNew Mex unit distributions	$ 310	$ 0	$ 0
Net assets of Predecessor retained by affiliate	0	0	34,829
Underwriting discounts and commissions	0	0	(22,612)
Accrued capital expenditures	1,810	8,426	722
Other	$ 0	$ (2,502)	$ 0