CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS AND COMPREHENSIVE LOSS - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Income Statement [Abstract]
Revenue	$ 32,902	$ 26,718	$ 91,692	$ 75,525
Cost of revenue	13,866	11,616	39,021	32,575
Gross profit	19,036	15,102	52,671	42,950
Operating expenses:
Research and development	15,701	11,512	41,047	32,456
Sales and marketing	2,354	1,927	7,255	5,383
General and administrative	3,214	2,572	9,535	7,047
Total operating expenses	21,269	16,011	57,837	44,886
Loss from operations	(2,233)	(909)	(5,166)	(1,936)
Other income (expense):
Interest expense		(382)		(1,398)
Change in fair value of convertible preferred stock warrant liability		317		(1,383)
Other income (expense), net	311	(4)	850	24
Total other income (expense)	311	(69)	850	(2,757)
Loss before income tax expense	(1,922)	(978)	(4,316)	(4,693)
Provision for (benefit from) income taxes	143	27	(50)	(331)
Net loss	$ (2,065)	$ (1,005)	$ (4,266)	$ (4,362)
Net loss per share, basic and diluted	$ (0.06)	$ (0.21)	$ (0.13)	$ (0.95)
Weighted-average shares used to compute net loss per share, basic and diluted	34,435	4,710	33,925	4,603
Comprehensive loss:
Net loss	$ (2,065)	$ (1,005)	$ (4,266)	$ (4,362)
Other comprehensive income (loss), net of tax:
Unrealized gains (loss) - short-term investments	55	2	(24)
Comprehensive loss	$ (2,010)	$ (1,003)	$ (4,290)	$ (4,362)