Condensed Consolidated Statements of Shareholder's Equity - USD ($) $ in Thousands	Total	Class A common stock [Member]	Class C common stock [Member]	Additional Paid In Capital	Non-controlling interests	Retained Earnings (Accumulated Deficit)
Balance at Dec. 31, 2018	$ 269,714	$ 5	$ 4	$ 137,866	$ 127,029	$ 4,810
Balance, shares at Dec. 31, 2018		45,855,000	40,000,000
Vested restricted stock grants, shares		4,000
Stock-based compensation	99			99
Distribution equivalent rights paid	(15)			(15)
Distributions to non-controlling interests	(8,559)				(8,559)
Dividends to shareholders	(9,171)					(9,171)
Net income (loss)	11,303				5,921	5,382
Balance at Mar. 31, 2019	263,371	$ 5	$ 4	137,950	124,391	1,021
Balance, shares at Mar. 31, 2019		45,859,000	40,000,000
Balance at Dec. 31, 2018	269,714	$ 5	$ 4	137,866	127,029	4,810
Balance, shares at Dec. 31, 2018		45,855,000	40,000,000
Distributions to non-controlling interests	(22,300)
Net income (loss)	26,562
Balance at Sep. 30, 2019	251,601	$ 5	$ 4	132,325	119,267
Balance, shares at Sep. 30, 2019		45,951,000	40,000,000
Balance at Mar. 31, 2019	263,371	$ 5	$ 4	137,950	124,391	1,021
Balance, shares at Mar. 31, 2019		45,859,000	40,000,000
Vested restricted stock grants, shares		3,000
Stock-based compensation	761			761
Distribution equivalent rights paid	(56)			(56)
Distributions to non-controlling interests	(7,397)				(7,397)
Dividends to shareholders	(8,025)			(3,248)		(4,777)
Net income (loss)	8,902				5,146	3,756
Balance at Jun. 30, 2019	257,556	$ 5	$ 4	135,407	122,140
Balance, shares at Jun. 30, 2019		45,862,000	40,000,000
Vested restricted stock grants, shares		89,000
Stock-based compensation	970			970
Distribution equivalent rights paid	(43)			(43)
Distributions to non-controlling interests	(6,346)				(6,346)
Dividends to shareholders	(6,893)			(4,009)		(2,884)
Net income (loss)	6,357				3,473	2,884
Balance at Sep. 30, 2019	251,601	$ 5	$ 4	132,325	119,267
Balance, shares at Sep. 30, 2019		45,951,000	40,000,000
Balance at Dec. 31, 2019	245,026	$ 5	$ 4	129,127	115,890
Balance, shares at Dec. 31, 2019		45,963,716	40,000,000
Vested restricted stock grants, shares		24,000
Stock-based compensation	836			836
Distribution equivalent rights paid	(42)			(42)
Distributions to non-controlling interests	(5,400)				(5,400)
Dividends to shareholders	(6,205)			(4,000)		(2,205)
Net income (loss)	4,509				2,304	2,205
Balance at Mar. 31, 2020	238,724	$ 5	$ 4	125,921	112,794
Balance, shares at Mar. 31, 2020		45,988,000	40,000,000
Balance at Dec. 31, 2019	245,026	$ 5	$ 4	129,127	115,890
Balance, shares at Dec. 31, 2019		45,963,716	40,000,000
Vested restricted stock grants, shares		130,466
Distributions to non-controlling interests	(7,600)
Net income (loss)	4,498
Balance at Sep. 30, 2020	235,817	$ 5	$ 4	125,239	110,569
Balance, shares at Sep. 30, 2020		46,094,183	40,000,000
Balance at Mar. 31, 2020	238,724	$ 5	$ 4	125,921	112,794
Balance, shares at Mar. 31, 2020		45,988,000	40,000,000
Vested restricted stock grants, shares		35,000
Stock-based compensation	969			969
Distribution equivalent rights paid	(12)			(12)
Distributions to non-controlling interests	(1,000)				(1,000)
Dividends to shareholders	(1,150)			(1,150)
Net income (loss)	(1,323)				(748)	(575)
Balance at Jun. 30, 2020	236,208	$ 5	$ 4	125,728	111,046	(575)
Balance, shares at Jun. 30, 2020		46,023,000	40,000,000
Vested restricted stock grants, shares		71,000
Stock-based compensation	893			893
Distribution equivalent rights paid	(15)			(15)
Distributions to non-controlling interests	(1,200)				(1,200)
Dividends to shareholders	(1,381)			(1,367)		(14)
Net income (loss)	1,312				723	$ 589
Balance at Sep. 30, 2020	$ 235,817	$ 5	$ 4	$ 125,239	$ 110,569
Balance, shares at Sep. 30, 2020		46,094,183	40,000,000