Components of Working Capital - Other Current Assets Table (Details) - USD ($) $ in Thousands		Mar. 31, 2018	Dec. 31, 2017
Other Current Assets [Line Items]
Natural gas liquids inventory		$ 9,275	$ 10,788
Imbalance receivables		6,293	1,640
Prepaid insurance		1,753	2,955
Contract assets		5,838	0
Other		97	0
Total other current assets	[1]	$ 23,256	$ 15,383

[1] Other current assets includes affiliate amounts of $5.7 million and zero as of March 31, 2018, and December 31, 2017, respectively.