Accrued Liabilities (Details) - USD ($) $ in Thousands	Jun. 30, 2017	Dec. 31, 2016	Jun. 30, 2016
Components of accrued liabilities [Abstract]
Preferred stock dividends payable	$ 2,901	$ 2,901
Accrued compensation and related charges	1,955	2,610
Advances from customers	1,286	238
Current portion of royalty payments	575	575
Dividends payable by consolidated joint ventures	512	499	$ 522
Accrued professional services	401	583
Accrued income taxes	264	203
Accrued product warranty	130	251
Other accrued liabilities	1,339	1,400
Accrued liabilities, total	$ 9,363	$ 9,260