Balance Sheet Components Accrued Liabilities (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Balance Sheet Components [Abstract]
2022	$ 1,385
Product Warranty Accrual, Payments	199	$ 222	$ 296
Accrued Liabilities, Current [Abstract]
Payroll and related expenses	6,053	7,241
Accrued payables	2,674	2,115
Operating lease liabilities, current portion	2,323	0
Lease financing, current portion	1,033	956
Product warranty	420	376
Customer Refund Liability, Current	631	629
Sales and use tax payable	599	379
Other	1,024	1,189
Total accrued payroll and other current liabilities	$ 14,757	$ 12,885