Accrued Liabilities (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Components of accrued liabilities
Payable in connection with repurchase of subsidiaries shares	$ 3,730	$ 1,439
Accrued compensation and related charges	2,933	4,417
Preferred stock dividends payable	2,901	2,901
Payable in connection with construction	943	1,457
Accrued income taxes	791	760
Payable in connection with land restoration of Nanjing JinMei factory	747	750
Advance from customers	657	374
Accrued product warranty	582	609
Accrued professional services	469	675
Current portion of operating lease liabilities	454	445
Other personnel-related costs	180	101
Other tax payable	124	295
Accrual for sales returns	111	81
Other accrued liabilities	1,076	1,691
Accrued liabilities, Total	$ 15,698	$ 15,995