Consolidated Statements of Operations - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Revenues
Total revenues	$ 20,381	$ 20,825	$ 40,652	$ 41,912
Operating expenses
Operations and maintenance (excluding depreciation and amortization reflected below)	6,603	6,233	12,763	13,098
General and administrative	878	988	1,922	2,105
Depreciation and amortization	966	771	1,927	1,756
Total operating expenses	8,447	7,992	16,612	16,959
Operating income	11,934	12,833	24,040	24,953
Other income (expense)
Interest income		20		40
Interest expense	(1,820)	(2,166)	(3,684)	(4,221)
Other		(73)		(73)
Total other expense	(1,820)	(2,219)	(3,684)	(4,254)
Income before income taxes and income from equity method investee	10,114	10,614	20,356	20,699
Income tax expense	(105)	(47)	(136)	(99)
Income from equity method investee	175	142	333	357
Net income	10,184	10,709	20,553	20,957
Affiliate [Member]
Revenues
Total revenues	18,997	19,133	37,980	37,915
Non-affiliate [Member]
Revenues
Total revenues	1,384	1,692	2,672	3,997
General Partner [Member]
Other income (expense)
Net income	204	213	411	418
Limited Partners [Member] | Common Units [Member]
Other income (expense)
Net income	$ 9,980	$ 10,496	$ 20,142	$ 20,539
Earnings per limited partner unit (basic and diluted):
Earnings per limited partner unit (basic and diluted)	$ 0.43	$ 0.45	$ 0.87	$ 0.89
Weighted average limited partner units outstanding (basic and diluted):
Weighted average limited partner units outstanding (basic and diluted)	23,138	23,120	23,138	23,119