Reporting Segments - Reconciliation of Segment Operating Income (Details) - USD ($) $ in Thousands	3 Months Ended				6 Months Ended
	Jun. 30, 2019	Mar. 31, 2019	Jun. 30, 2018	Mar. 31, 2018	Jun. 30, 2019	Jun. 30, 2018
Reconciliation of segment operating income (loss) to net income (loss)
Segment operating income	$ 11,092		$ 10,505		$ 18,888	$ 21,419
General and administrative expense	(4,171)		(6,919)		(8,920)	(12,084)
Unit-based compensation expense	(175)		(1,347)		(810)	(2,785)
Interest expense, net	(2,814)		(2,780)		(5,600)	(5,379)
Other income (expense)	21		(1,254)		67	(1,524)
Income tax expense	(76)				(122)
Net income (loss)	3,877	$ (374)	(1,795)	$ 1,442	3,503	(353)
Production
Reconciliation of segment operating income (loss) to net income (loss)
Segment operating income	1,481		1,367		(1,620)	2,406
Midstream
Reconciliation of segment operating income (loss) to net income (loss)
Segment operating income	$ 9,611		$ 9,138		$ 20,508	$ 19,013