Reporting Segments (Segment Information) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016	Dec. 31, 2016
Operating Revenues
Natural gas sales	$ 2,252	$ 600	$ 5,031	$ 4,275
Oil sales	8,109	(2,756)	19,459	2,587
Natural gas liquids sales	492	244	959	520
Gathering and transportation sales	14,176	14,258	25,387	28,133
Total revenues	25,029	12,346	50,836	35,515
Operating expenses:
Lease operating expenses	3,881	4,178	8,864	9,151
Transportation operating expenses	3,032	3,014	6,328	6,068
Cost of sales	40	63	77	193
Production taxes	353	326	826	547
General and administrative	6,353	4,978	11,962	10,697
Unit-based compensation expense	780	1,091	1,320	1,529
Depreciation, depletion and amortization	8,937	6,129	21,118	13,317
Asset impairments			4,688	1,309
Accretion expense	240	315	498	630	$ 1,127
Total operating expenses	23,616	20,094	55,681	43,441
Operating income (loss)	1,413	(7,748)	(4,845)	(7,926)
Upstream
Operating Revenues
Natural gas sales	2,252	600	5,031	4,275
Oil sales	8,109	(2,756)	19,459	2,587
Natural gas liquids sales	492	244	959	520
Total revenues	10,853	(1,912)	25,449	7,382
Operating expenses:
Lease operating expenses	3,648	3,905	8,372	8,780
Cost of sales	40	63	77	193
Production taxes	353	326	826	547
General and administrative	4,892	3,550	8,996	7,984
Unit-based compensation expense	780	1,091	1,320	1,529
Depreciation, depletion and amortization	2,924	1,035	6,205	3,149
Asset impairments			4,688	1,309
Accretion expense	172	253	364	507
Total operating expenses	12,809	10,223	30,848	23,998
Operating income (loss)	(1,956)	(12,135)	(5,399)	(16,616)
Midstream
Operating Revenues
Gathering and transportation sales	14,176	14,258	25,387	28,133
Total revenues	14,176	14,258	25,387	28,133
Operating expenses:
Lease operating expenses	233	273	492	371
Transportation operating expenses	3,032	3,014	6,328	6,068
General and administrative	1,461	1,428	2,966	2,713
Depreciation, depletion and amortization	6,013	5,094	14,913	10,168
Accretion expense	68	62	134	123
Total operating expenses	10,807	9,871	24,833	19,443
Operating income (loss)	$ 3,369	$ 4,387	$ 554	$ 8,690