Consolidated Statements of Operations - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Revenues
Total revenues	$ 21,382	$ 20,154	$ 62,034	$ 62,066
Operating expenses
Operations and maintenance (excluding depreciation and amortization reflected below)	6,647	6,216	19,410	19,314
General and administrative	1,116	949	3,038	3,054
Depreciation and amortization	940	991	2,867	2,747
Total operating expenses	8,703	8,156	25,315	25,115
Operating income	12,679	11,998	36,719	36,951
Other income (expense)
Interest income		21		61
Interest expense	(2,498)	(2,103)	(6,182)	(6,324)
Other		88		15
Total other expense	(2,498)	(1,994)	(6,182)	(6,248)
Income before income taxes and income from equity method investee	10,181	10,004	30,537	30,703
Income tax expense	(30)	(45)	(166)	(144)
Income from equity method investee	155	173	488	530
Net income	10,306	10,132	30,859	31,089
Affiliate [Member]
Revenues
Total revenues	20,347	18,836	58,327	56,751
Non-affiliate [Member]
Revenues
Total revenues	1,035	1,318	3,707	5,315
General Partner [Member]
Other income (expense)
Net income	206	203	617	621
Limited Partners [Member] | Common Units [Member]
Other income (expense)
Net income	$ 10,100	$ 9,929	$ 30,242	$ 30,468
Earnings per limited partner unit (basic and diluted):
Common units	$ 0.44	$ 0.43	$ 1.31	$ 1.32
Weighted average limited partner units outstanding (basic and diluted):
Common units	23,161	23,138	23,145	23,125