Employee Benefit Plans and Stock-based Compensation - Stock-Based Compensation (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Total stock-based compensation	$ 2,623	$ 2,346	$ 1,925
Net effect on net income	$ 2,623	$ 2,346	$ 1,925
Shares used in computing basic net income (loss) per share	40,152,000	39,487,000	39,049,000
Shares used in computing diluted net income per share	41,025,000	39,487,000	40,265,000
Effect on basic net income per share	$ 0.07	$ (0.06)	$ 0.05
Effect on diluted net income per share	$ 0.06	$ (0.06)	$ 0.05
Cost of Revenue [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Total stock-based compensation	$ 116	$ 125	$ 92
Selling, General and Administrative [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Total stock-based compensation	2,000	1,778	1,520
Research and Development [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Total stock-based compensation	$ 507	$ 443	$ 313
Options
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock options grants in period	0	430,000	246,000
Weighted-average grant date fair value of stock options granted (in dollars per share)		$ 1.48	$ 2.74