Stock-Based Compensation (Details 3) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Summary of stock-based compensation expense
Stock-based compensation expense	$ 72	$ 255	$ 1,075
Remaining unamortized expense of stock-based compensation	11
Research and development [Member]
Summary of stock-based compensation expense
Stock-based compensation expense		48	484
Sales and marketing [Member]
Summary of stock-based compensation expense
Stock-based compensation expense	50	150	296
General and administrative [Member]
Summary of stock-based compensation expense
Stock-based compensation expense	$ 22	$ 57	$ 295