Stockholders' Equity (Details 6) - USD ($) $ in Thousands	12 Months Ended
Stockholders' Equity (Details 6) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Stock-based compensation expense	$ 1,081	$ 1,060	$ 301
Cost of Sales [Member]
Stock-based compensation expense	143
Research and Development Expense [Member]
Stock-based compensation expense	456	256	119
General and Administrative Expense [Member]
Stock-based compensation expense	$ 482	$ 804	$ 182