Accrued Liabilities (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017	Mar. 31, 2017
Components of accrued liabilities [Abstract]
Preferred stock dividends payable	$ 2,901	$ 2,901
Accrued compensation and related charges	2,058	3,205
Advance from customers	1,061	924
Dividends payable by consolidated joint ventures	552	533	$ 503
Current portion of royalty payments	431	575
Accrued income taxes	375	270
Accrued professional services	251	570
Other tax payable	215	395
Other personnel related costs	213	230
Accrued product warranty	117	133
Other accrued liabilities	1,016	1,413
Accrued liabilities, total	$ 9,190	$ 11,149