Stock-Based Compensation - Summary of Non-Vested Options (Details) - Non Vested	12 Months Ended
	Dec. 31, 2018 $ / shares shares
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Non-vested options at beginning of period (in shares) | shares	1,184,344
Options, granted (in shares) | shares	839,785
Option, Vested (in shares) | shares	(699,572)
Options, Forfeited (in shares) | shares	(210,678)
Non-vested options at end of period (in shares) | shares	1,113,879
Share-based Compensation Arrangement by Share-based Payment Award, Options, Nonvested, Weighted Average Grant Date Fair Value [Abstract]
Non-vested options at beginning of period (in dollars per share) | $ / shares	$ 3.48
Granted (in dollars per share) | $ / shares	1.44
Vested (in dollars per share) | $ / shares	3.54
Forfeited (in dollars per share) | $ / shares	3.37
Non-vested options at end of period (in dollars per share) | $ / shares	$ 2.00