Segments (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016	Dec. 31, 2016
Segment Reporting Information [Line Items]
Midstream Services — Affiliate	$ 50,314	$ 32,123
Income (Loss) before Income Taxes	34,520	21,820
Total Assets	427,178		$ 369,359
Gathering Systems (1)
Segment Reporting Information [Line Items]
Midstream Services — Affiliate	29,995	23,248
Income (Loss) before Income Taxes	23,254	19,860
Total Assets	287,213		224,861
Fresh Water Delivery (1)
Segment Reporting Information [Line Items]
Midstream Services — Affiliate	20,319	8,875
Income (Loss) before Income Taxes	13,333	4,321
Total Assets	65,525		54,542
Investments and Other (1)
Segment Reporting Information [Line Items]
Midstream Services — Affiliate	0	0
Income (Loss) before Income Taxes	(2,067)	$ (2,361)
Total Assets	$ 74,440		$ 89,956