Warrants Outstanding and Exercisable (Details) shares in Thousands	Dec. 31, 2018 $ / shares shares	Dec. 31, 2016 $ / shares
Warrant, exercise price	$ 2.47	$ 2.23
Warrants, Outstanding as of end of period | shares	1,973
Warrants outstanding, weighted average remaining contractual life, years	0.21
Warrants outstanding, weighted average exercise price	2.47
Warrants, Exercisable at end of period | shares	1,973
Warrants exercisable, weighted average exercise price	$ 2.47