Quarterly Results (Unaudited) (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
Product Information [Line Items]
Revenue, net	$ 16,777	$ 18,294	$ 16,249	$ 14,545	$ 14,767	$ 11,340	$ 16,432	$ 17,663	$ 65,865	$ 60,202	$ 63,012
Cost of revenues										32,830	28,325
Gross profit	5,662	6,719	4,784	5,220	5,863	2,538	8,037	10,934	22,385	27,372
Operating (loss) income	(5,445)	(1,213)	(4,910)	(3,531)	(4,943)	(8,039)	(1,782)	2,967	(15,099)	(11,797)	2,542
Net loss	(14,390)	(3,945)	(13,119)	(4,802)	(6,121)	(8,982)	(919)	831	(36,256)	(15,191)	(11,985)
Net income (loss) attributable to common stockholders	$ (14,390)	$ (3,945)	$ (13,119)	$ (4,802)	$ (6,121)	$ (8,982)	$ (919)	$ 831	$ (36,256)	$ (15,191)	(11,985)
Basic income (loss) per share (in dollars per share)	$ (0.27)	$ (0.07)	$ (0.25)	$ (0.09)	$ (0.11)	$ (0.17)	$ (0.02)	$ 0.02	$ (0.68)	$ (0.28)
Diluted income (loss) per share (in dollars per share)	$ (0.27)	$ (0.07)	$ (0.25)	$ (0.09)	$ (0.11)	$ (0.17)	$ (0.02)	$ 0.02	$ (0.68)	$ (0.28)
Adjustment
Product Information [Line Items]
Revenue, net										$ (7,049)	(3,869)
Cost of revenues										$ (7,049)	$ (3,869)
Adjustment | Immaterial Accounting Errors
Product Information [Line Items]
Revenue, net					$ 1,300	$ 1,500	$ 2,000	$ 2,200
Cost of revenues					$ 1,300	$ 1,500	$ 2,000	$ 2,200