Stock-Based Compensation - Schedule of Stock Option Activity (Details) - $ / shares	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Number of options outstanding (in shares), ending	2,334,731
Employee Stock Option
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Number of options outstanding (in shares), beginning	4,352,391	4,299,810
Number of options granted (in shares)	2,468,129	839,785
Number of options exercised (in shares)	0	(239,000)
Number of options expired (in shares)	(761,780)	0
Number of options forfeited (in shares)	(891,001)	(548,204)
Number of options outstanding (in shares), ending	5,167,739	4,352,391
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price [Abstract]
Shares issuable under options exercise price per share (in dollars per share)	$ 4.61	$ 5.09
Granted, exercise price per share (in dollars per share)	0.61	3.34
Exercised, exercise price per share (in dollars per share)	0	1.05
Expired, exercise price per share (in dollars per share)	2,420	0
Forfeited, exercise price per share (in dollars per share)	1.04	8.04
Shares issuable under options exercise price per share (in dollars per share)	3.34	4.61
Employee Stock Option | Minimum
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price [Abstract]
Shares issuable under options exercise price per share (in dollars per share)	0.79	0.79
Granted, exercise price per share (in dollars per share)	0.55	1.73
Exercised, exercise price per share (in dollars per share)		1.02
Expired, exercise price per share (in dollars per share)	1.02
Forfeited, exercise price per share (in dollars per share)	0.66	2.02
Shares issuable under options exercise price per share (in dollars per share)	0.55	0.79
Employee Stock Option | Maximum
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price [Abstract]
Shares issuable under options exercise price per share (in dollars per share)	10.67	10.67
Granted, exercise price per share (in dollars per share)	1.80	4.25
Exercised, exercise price per share (in dollars per share)		1.83
Expired, exercise price per share (in dollars per share)	10.67
Forfeited, exercise price per share (in dollars per share)	8.67	10.67
Shares issuable under options exercise price per share (in dollars per share)	$ 10.67	$ 10.67