Reporting Segments (Segment Information) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016	Dec. 31, 2016
Operating Revenues
Natural gas sales	$ 787	$ 4,434	$ 5,818	$ 8,709
Oil sales	3,061	2,159	22,520	4,746
Natural gas liquids sales	514	264	1,473	784
Gathering and transportation sales	14,234	12,997	39,621	41,130
Total revenues	18,596	19,854	69,432	55,369
Operating expenses:
Lease operating expenses	1,735	2,767	10,599	11,918
Transportation operating expenses	2,661	3,111	8,989	9,179
Cost of sales		99	77	292
Production taxes	340	290	1,166	837
General and administrative	5,614	6,286	17,576	16,983
Unit-based compensation expense	631	90	1,951	1,619
Loss (gain) on sale of assets	(2,546)	219	(2,546)	219
Depreciation, depletion and amortization	6,899	7,507	28,017	20,824
Asset impairments			4,688	1,309
Accretion expense	149	271	647	901	$ 1,127
Total operating expenses	15,483	20,640	71,164	64,081
Operating income (loss)	3,113	(786)	(1,732)	(8,712)
Upstream
Operating Revenues
Natural gas sales	787	4,434	5,818	8,709
Oil sales	3,061	2,159	22,520	4,746
Natural gas liquids sales	514	264	1,473	784
Total revenues	4,362	6,857	29,811	14,239
Operating expenses:
Lease operating expenses	1,585	2,650	9,957	11,430
Cost of sales		99	77	292
Production taxes	340	290	1,166	837
General and administrative	4,199	4,778	13,195	12,762
Unit-based compensation expense	631	90	1,951	1,619
Loss (gain) on sale of assets	(2,546)	219	(2,546)	219
Depreciation, depletion and amortization	1,756	2,411	7,961	5,560
Asset impairments			4,688	1,309
Accretion expense	80	207	444	714
Total operating expenses	6,045	10,744	36,893	34,742
Operating income (loss)	(1,683)	(3,887)	(7,082)	(20,503)
Midstream
Operating Revenues
Gathering and transportation sales	14,234	12,997	39,621	41,130
Total revenues	14,234	12,997	39,621	41,130
Operating expenses:
Lease operating expenses	150	117	642	488
Transportation operating expenses	2,661	3,111	8,989	9,179
General and administrative	1,415	1,508	4,381	4,221
Depreciation, depletion and amortization	5,143	5,096	20,056	15,264
Accretion expense	69	64	203	187
Total operating expenses	9,438	9,896	34,271	29,339
Operating income (loss)	$ 4,796	$ 3,101	$ 5,350	$ 11,791