Accrued Liabilities (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Components of accrued liabilities
Preferred stock dividends payable	$ 2,901	$ 2,901
Accrued compensation and related charges	2,552	3,307
Payable in connection with land restoration of Nanjing JinMei factory	691	703
Payable in connection with construction	604	1,447
Advance from customers	429	396
Current portion of operating lease liabilities	363	319
Accrued product warranty	362	387
Accrued professional services	324	630
Current portion of royalty payments	300
Accrued income taxes	238	171
Other tax payable	162	50
Payable in connection with repurchase of subsidiaries shares	151	151
Other personnel-related costs	56	180
Accrual for sales returns	13	26
Other accrued liabilities	1,225	1,013
Accrued liabilities, Total	$ 10,371	$ 11,681