Unaudited Quarterly Operating Results (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Quarterly Financial Information [Line Items]
Total Revenue	$ 11,993	$ 15,767	$ 5,406	$ 13,738	$ 11,871	$ 11,997	$ 5,783	$ 5,791	$ 46,904	$ 35,442
Net income (loss)	306	3,487	(1,013)	1,455	321	(26)	(203)	(1,913)	4,235	(1,821)	$ 757
Net (Loss) Income attributable to Common Stockholders	$ 307	$ 3,488	$ (997)	$ 1,457	$ 303	$ (22)	$ (176)	$ (1,902)	$ 4,255	$ (1,797)	$ 800
Net (Loss) Income Per Share (in dollars per share)	$ 0.01	$ 0.13	$ (0.04)	$ 0.06	$ 0.01	$ 0.00	$ (0.01)	$ (0.09)	$ 0.16	$ (0.08)	$ 0.04
Net (Loss) Income, Per Share attributable to Common Stockholders (in dollars per share)	$ 0.01	$ 0.13	$ (0.04)	$ 0.06	$ 0.01	$ 0.00	$ (0.01)	$ (0.09)	$ 0.16	$ (0.08)	$ 0.04
Reportable Segment
Quarterly Financial Information [Line Items]
Segment Profit (Loss)	$ 934	$ 4,815	$ 115	$ 4,277	$ 1,973	$ 720	$ 313	$ (811)	$ 10,141	$ 2,195