Condensed Consolidated Statements of Comprehensive Loss (Unaudited) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Revenue
Product revenue	$ 14,867	$ 12,291	$ 35,443	$ 24,761
License and other revenue	74	68	143	133
Total revenue	14,941	12,359	35,586	24,894
Cost of revenue	10,527	7,475	27,007	13,827
Gross profit	4,414	4,884	8,579	11,067
Operating expenses:
Sales and marketing	5,187	5,159	10,589	9,853
General and administrative	4,547	3,978	8,680	7,988
Research and development	10,482	13,014	15,902	24,049
Total operating expenses	20,216	22,151	35,171	41,890
Loss from operations	(15,802)	(17,267)	(26,592)	(30,823)
Other income (expense):
Interest income	202	54	389	106
Interest expense	(797)	(755)	(1,585)	(1,261)
Other income (expense)	(90)	56	(102)	151
Total other income (expense)	(685)	(645)	(1,298)	(1,004)
Loss before provision for income taxes	(16,487)	(17,912)	(27,890)	(31,827)
Income tax expense	34	77	54	78
Net loss	$ (16,521)	$ (17,989)	$ (27,944)	$ (31,905)
Net loss per share, basic and diluted	$ (0.30)	$ (0.37)	$ (0.50)	$ (0.67)
Weighted average number of shares outstanding basic and diluted	55,547	48,067	55,377	47,460
Other comprehensive loss:
Net loss	$ 16,521	$ 17,989	$ 27,944	$ 31,905
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Adjustment, Net of Tax	14	3	(20)	94
Other Comprehensive Income (Loss), Unrealized Holding Gain (Loss) on Securities Arising During Period, Net of Tax	14	1	22	(15)
Other Comprehensive Income (Loss), Net of Tax	28	4	2	79
Total comprehensive loss	$ (16,493)	$ (17,985)	$ (27,942)	$ (31,826)