Balance Sheets Details - Accrued Liabilities (Details) - USD ($)	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Components of accrued liabilities
Accrued compensation and related charges	$ 4,774,000	$ 5,115,000
Payable in connection with construction in progress	4,135,000	2,974,000
Preferred stock dividends payable	2,901,000	2,901,000
Accrued professional services	930,000	880,000
Other tax payable	867,000	392,000
Accrued income taxes	729,000	539,000
Accrued product warranty	669,000	743,000	$ 609,000
Current portion of operating lease liabilities	485,000	488,000
Advances from customers	338,000	946,000
Other personnel-related costs	291,000	279,000
Accrual for sales returns	112,000	48,000
Other accrued liabilities	1,933,000	1,752,000
Accrued liabilities, Total	$ 18,164,000	$ 17,057,000