Consolidated Statements of Operations - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Income Statement [Abstract]
Revenue	$ 356,804	$ 322,540	$ 292,894
Cost of goods sold	267,991	256,367	231,415
Gross profit	88,813	66,173	61,479
Operating expenses:
Research and development	57,634	53,818	58,287
Sales and marketing	16,088	16,728	17,760
General and administrative	29,759	30,403	34,453
Amortization of purchased intangible assets	119	475	472
Asset sale related costs	397	427	130
Restructuring charges	261	3,135	3,934
Litigation settlement	0	2,645	0
Loss (gain) on asset sale	(903)	200	(2,193)
Total operating expenses	103,355	107,831	112,843
Loss from operations	(14,542)	(41,658)	(51,364)
Interest income	376	397	198
Interest expense	(1,919)	(2,493)	(1,362)
Other income, net	642	1,446	104
Total interest and other income (expense), net	(901)	(650)	(1,060)
Loss before income taxes	(15,443)	(42,308)	(52,424)
Provision for income taxes	(1,633)	(1,329)	(909)
Net loss	$ (17,076)	$ (43,637)	$ (53,333)
Basic and diluted net loss per share (USD per share)	$ (0.36)	$ (0.97)	$ (1.23)
Weighted average shares used to compute basic and diluted net loss per share (in shares)	47,304	45,144	43,431