Segment Information (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016	Dec. 31, 2016
Segment Reporting Information [Line Items]
Midstream Services — Affiliate	$ 56,755	$ 47,167	$ 161,186	$ 112,259
Midstream Services — Third Party	6,356	0	10,022	0
Total Revenues	63,111	47,167	171,208	112,259
Income (Loss) before Income Taxes	43,789	33,472	117,416	78,599
Total Assets	644,091		644,091		$ 369,359
Gathering Systems
Segment Reporting Information [Line Items]
Midstream Services — Affiliate	39,166	25,887	102,930	72,291
Midstream Services — Third Party	1,574		1,574
Total Revenues	40,740		104,504
Income (Loss) before Income Taxes	28,307	19,280	70,633	56,390
Total Assets	459,647		459,647		224,861
Fresh Water Delivery — Affiliate
Segment Reporting Information [Line Items]
Midstream Services — Affiliate	17,589	21,280	58,256	39,968
Midstream Services — Third Party	4,782		8,448
Total Revenues	22,371		66,704
Income (Loss) before Income Taxes	17,823	18,186	53,298	29,272
Total Assets	66,839		66,839		54,542
Investments and Other
Segment Reporting Information [Line Items]
Midstream Services — Affiliate	0	0	0	0
Midstream Services — Third Party	0		0
Total Revenues	0		0
Income (Loss) before Income Taxes	(2,341)	$ (3,994)	(6,515)	$ (7,063)
Total Assets	$ 117,605		$ 117,605		$ 89,956