Condensed Consolidated Statements of Operations (Unaudited) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Revenue from contract with customer	$ 64,358	$ 79,029
Lease revenue	14,752	14,703
Total revenue	79,110	93,732
Costs and expenses:
Operating expense	24,939	27,243
General and administrative expense	3,540	3,693
Asset impairment expense	5,122	1,119
Total costs and expenses	76,076	87,416
Gain (loss) on sale of assets	(185)	1,724
Operating income	2,849	8,040
Other income (expenses):
Other income	558
Interest expense	(3,399)	(4,271)
Income before income taxes	8	3,769
Provision for income taxes	8	12
Net income		3,757
Allocation of net income(loss) for calculation of earnings per unit:
General partner interest in net income(loss)		105
Preferred interest in net income	6,279	6,279
Net loss available to limited partners	$ (6,279)	$ (2,627)
Basic and diluted net loss per common unit (in dollars per share)	$ (0.15)	$ (0.06)
Weighted average common units outstanding - basic and diluted (in shares)	41,015	40,678
Third Party [Member]
Lease revenue	$ 9,831	$ 9,763
Costs and expenses:
Cost of product sales	14,221	24,587
Related Party [Member]
Lease revenue	4,921	4,940
Costs and expenses:
Cost of product sales	28,254	30,774
Service [Member] | Third Party [Member]
Revenue from contract with customer	13,229	15,886
Service [Member] | Related Party [Member]
Revenue from contract with customer	4,077	4,219
Product [Member] | Third Party [Member]
Revenue from contract with customer	$ 47,052	$ 58,924