Condensed Consolidated Statements of Operations and Comprehensive Loss - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Condensed Consolidated Statements of Operations and Comprehensive Loss [Abstract]
Revenue	$ 40,824	$ 58,906	$ 94,049	$ 112,872
Cost of revenue	13,170	15,013	27,511	29,108
Gross profit	27,654	43,893	66,538	83,764
Operating expenses:
Research and development expenses	10,036	9,804	21,623	17,980
Selling, general and administrative expenses	24,903	37,928	67,654	74,943
Total operating expenses	34,939	47,732	89,277	92,923
Loss from operations	(7,285)	(3,839)	(22,739)	(9,159)
Other income (expense):
Interest expense	(1,231)	(879)	(2,459)	(1,741)
Interest income	263	636	668	1,356
Other	29	(9)	(94)	(116)
Loss before income tax expense	(8,224)	(4,091)	(24,624)	(9,660)
Income tax expense	12	10	20	76
Net loss	$ (8,236)	$ (4,101)	$ (24,644)	$ (9,736)
Basic and diluted net loss per share	$ (0.20)	$ (0.11)	$ (0.61)	$ (0.26)
Weighted average shares outstanding — basic and diluted	41,649	37,334	40,160	37,156
Comprehensive loss:
Unrealized gain on investments	$ 174	$ 17	$ 111	$ 83
Foreign currency translation adjustment	101	115	(49)	(38)
Other comprehensive income	275	132	62	45
Net loss	(8,236)	(4,101)	(24,644)	(9,736)
Comprehensive loss, net of tax	$ (7,961)	$ (3,969)	$ (24,582)	$ (9,691)