Senior Convertible Bonds (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Debt Instrument [Line Items]
10% Senior Convertible Bonds	$ 3,470	$ 3,470	$ 3,470
Debt discount amortization, net	(993)	(1,267)	(1,513)
Bonds converted to shares	(203)	(111)	(13)
Offering cost, net	(63)	(90)	(118)
10% senior Convertible bonds - Long Term Liability	$ 2,211	$ 2,002	$ 1,826