Consolidated Statements of Operations and Comprehensive Loss - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Income Statement [Abstract]
Revenue	$ 387,289	$ 326,674	$ 228,504
Cost of revenue	113,965	98,981	75,433
Gross profit	273,324	227,693	153,071
Operating expenses
Research and development	48,459	37,560	33,729
Sales, general and administrative	266,608	219,712	142,423
Total operating expenses	315,067	257,272	176,152
Loss from operations	(41,743)	(29,579)	(23,081)
Interest income	4,871	3,164	1,685
Interest expense	(10,401)	(9,902)	(6,394)
Other income (expense), net	(1,164)	1,067	(1,097)
Loss on extinguishment of debt			(1,268)
Loss before income taxes	(48,437)	(35,250)	(30,155)
Provision for income taxes	768	1,408	1,623
Net loss	(49,205)	(36,658)	(31,778)
Other comprehensive loss:
Changes in foreign currency translation adjustment	(37)	(360)	(163)
Changes in unrealized gains (losses) on short-term investments, net	202	(204)	(340)
Net change in other comprehensive loss	165	(564)	(503)
Comprehensive loss	$ (49,040)	$ (37,222)	$ (32,281)
Net loss per share, basic and diluted	$ (1.64)	$ (1.25)	$ (1.12)
Weighted average number of common shares used to compute basic and diluted net loss per share	30,051,961	29,424,054	28,485,003