Stock-based Compensation (Details 1) - 2014 Plan [Member] $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2017 USD ($) $ / shares shares
Options Outstanding
Options Outstanding, Beginning Balance | shares	2,477
Options Outstanding, Options Granted | shares	1,112
Options Outstanding, Options Exercised | shares	(82)
Options Outstanding, Options Forfeited | shares	(200)
Options Outstanding, Options Expired | shares	(151)
Options Outstanding, Ending Balance | shares	3,156
Options Outstanding, Vested and expected to vest | shares	3,156
Options Outstanding, Exercisable | shares	1,581
Weighted Average Exercise Price, Beginning Balance | $ / shares	$ 6.50
Weighted Average Exercise Price, Options Granted | $ / shares	1.79
Weighted Average Exercise Price, Options Exercised | $ / shares	0.57
Weighted Average Exercise Price, Options Forfeited | $ / shares	7.04
Weighted Average Exercise Price, Options Expired | $ / shares	6.46
Weighted Average Exercise Price, Ending Balance | $ / shares	4.96
Weighted Average Exercise Price, Vested and expected to vest | $ / shares	4.96
Weighted Average Exercise Price, Exercisable | $ / shares	$ 6.35
Weighted Average Remaining Contractual Life (Years), Ending Balance	7 years 8 months 5 days
Weighted Average Remaining Contractual Life (Years), Vested and expected to vest	7 years 8 months 5 days
Weighted Average Remaining Contractual Life (Years), Exercisable	6 years 4 months 20 days
Aggregate Intrinsic Value, Ending Balance | $	$ 683
Aggregate Intrinsic Value, Vested and expected to vest | $	683
Aggregate Intrinsic Value, Exercisable | $	$ 53