Stock-based Compensation - RSU (Details) $ / shares in Units, shares in Thousands	6 Months Ended
	Jun. 30, 2017 USD ($) $ / shares shares
Options [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Compensation costs related to unvested stock options not yet recognized | $	$ 1,600,000
Value of estimated forfeitures | $	$ 183,000
Weighted-average period of amortization	2 years 7 months 6 days
Restricted Stock Awards [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted-average period of amortization	1 year 1 month 6 days
Shares [Roll Forward]
Non-vested, beginning of period (in shares) | shares	325
Granted (in shares) | shares	26
Vested (in shares) | shares	(74)
Non-vested, end of period (in shares) | shares	277
Weighted Average Grant Date Fair Value [Roll Forward]
Non-vested, beginning of period (in dollars per share) | $ / shares	$ 3.27
Granted (in dollars per share) | $ / shares	6.80
Vested (in dollars per share) | $ / shares	3.22
Non-vested, end of period (in dollars per share) | $ / shares	$ 3.62
Unrecognized compensation expense related to restricted stock awards | $	$ 816,000