Stock-Based Compensation (Details) - USD ($) $ / shares in Units, $ in Thousands	1 Months Ended	3 Months Ended		6 Months Ended
	Apr. 30, 2017	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Share-based Compensation [Abstract]
Withholding taxes paid on shares issued upon conversion of RSUs				$ 47	$ 33
Stock-based compensation expense				1,713	2,008
Selling, General and Administrative Expense [Member]
Share-based Compensation [Abstract]
Stock-based compensation expense		$ 498	$ 467	872	855
Research and Development Expense [Member]
Share-based Compensation [Abstract]
Stock-based compensation expense		$ 430	$ 655	$ 841	$ 1,154
Stock Options [Member]
Share-based Compensation [Abstract]
Options granted (in shares)		345,000	340,000	345,000	1,010,000
Options granted, weighted average grant date fair value (in dollars per share)		$ 4.63	$ 2.31	$ 4.63	$ 2.52
Dividend yield				0.00%	0.00%
Expected stock price volatility				92.00%	85.00%
Risk-free interest rate				2.09%	2.65%
Expected option term				6 years	6 years
Unrecognized stock-based compensation expense expected to be recognized related to non-vested stock options		$ 6,284		$ 6,284
Weighted average amortization period				2 years 6 months
Options exercised (in shares)				663,816
Restricted Stock Units (RSUs) [Member]
Share-based Compensation [Abstract]
RSUs granted (in shares)		229,996	226,663	229,996	246,663
Weighted average grant date fair value of RSU's granted (in dollars per share)		$ 6.06	$ 3.19	$ 6.06	$ 3.28
Withholding taxes paid on shares issued upon conversion of RSUs		$ 47	$ 33	$ 47	$ 33
Unrecognized stock-based compensation expense expected to be recognized related to non-vested RSUs		$ 2,396		$ 2,396
Weighted average amortization period				2 years 10 months 2 days
New shares of common stock issued as a result of vesting RSUs (in shares)				182,618
2013 Plan [Member]
Share-based Compensation [Abstract]
Additional shares authorized for issuance (in shares)	2,500,000
Shares authorized for issuance (in shares)		16,624,469		16,624,469
Shares available for grant (in shares)		1,128,903		1,128,903