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Quarterly Financial Data - Unaudited (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								6 Months Ended	9 Months Ended	12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Jun. 30, 2019	Sep. 30, 2019	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Total revenue	$ 19,706	$ 20,852	$ 19,895	$ 17,991	$ 16,160	$ 16,396	$ 18,204	$ 14,718			$ 78,444	$ 65,478	$ 67,693
Operating income (loss)	(1,289)	(14,021)	302	(145)	(491)	(500)	179	305			(15,153)	(507)	1,471
Net income (loss)	$ (1,710)	$ (12,579)	$ 327	$ 98	$ (749)	$ (118)	$ 211	$ 190			$ (13,864)	$ (466)	$ 19,794
Earnings (loss) per share - Basic (in dollars per share)	$ (0.13)	$ (0.96)	$ 0.02	$ 0.01	$ (0.06)	$ (0.01)	$ 0.02	$ 0.01	$ 0.03	$ (0.93)	$ (1.06)	$ (0.04)	$ 1.54
Earnings (loss) per share - Diluted (in dollars per share)	$ (0.13)	$ (0.96)	$ 0.02	$ 0.01	$ (0.06)	$ (0.01)	$ 0.02	$ 0.01	$ 0.03	$ (0.93)	$ (1.06)	$ (0.04)	$ 1.51
As Reported
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Total revenue		$ 20,852	$ 19,895	$ 17,991	$ 16,160	$ 16,396	$ 18,204	$ 14,718				$ 65,478	$ 67,693
Operating income (loss)		(13,561)	593	209	106	(44)	226	350				638	1,567
Net income (loss)		$ (12,232)	$ 573	$ 357	$ (282)	$ 236	$ 247	$ 225				$ 426	$ 19,851
Earnings (loss) per share - Basic (in dollars per share)		$ (0.93)	$ 0.04	$ 0.03	$ (0.02)	$ 0.02	$ 0.02	$ 0.02				$ 0.03	$ 1.55
Earnings (loss) per share - Diluted (in dollars per share)		$ (0.93)	$ 0.04	$ 0.03	$ (0.02)	$ 0.02	$ 0.02	$ 0.02				$ 0.03	$ 1.51
Revisions | Revision Of Prior Period Financial Statements
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Total revenue		$ 0	$ 0	$ 0	$ 0	$ 0	$ 0	$ 0				$ 0	$ 0
Operating income (loss)		(460)	(291)	(354)	(597)	(456)	(47)	(45)				(1,145)	(96)
Net income (loss)		$ (347)	$ (246)	$ (259)	$ (467)	$ (354)	$ (36)	$ (35)			$ 1,130	$ (892)	$ (57)
Earnings (loss) per share - Basic (in dollars per share)		$ (0.03)	$ (0.02)	$ (0.02)	$ (0.04)	$ (0.03)	$ 0	$ (0.01)				$ (0.07)	$ (0.01)
Earnings (loss) per share - Diluted (in dollars per share)		$ (0.03)	$ (0.02)	$ (0.02)	$ (0.04)	$ (0.03)	$ 0	$ (0.01)				$ (0.07)	$ 0

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