Accrued Liabilities (Details) - USD ($) $ in Thousands	Jun. 30, 2020	Dec. 31, 2019
Components of accrued liabilities
Preferred stock dividends payable	$ 2,901	$ 2,901
Accrued compensation and related charges	2,762	3,307
Payable in connection with land restoration of Nanjing JinMei factory	693	703
Accrued income taxes	689	171
Advance from customers	520	396
Accrued professional services	458	630
Current portion of operating lease liabilities	382	319
Accrued product warranty	352	387
Current portion of royalty payments	300
Accrual for sales returns	90	26
Payable in connection with repurchase of subsidiaries shares	78	151
Other tax payable	62	50
Other personnel-related costs	55	180
Payable in connection with construction	46	1,447
Other accrued liabilities	1,123	1,013
Accrued liabilities, Total	$ 10,511	$ 11,681