Stock and Stock Options - Summary of Stock Option Activity Under the Stock Option Plans (Details) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2019 USD ($) $ / shares shares
Shares
Outstanding shares, Beginning balance (in shares) | shares	1,264,394
Shares granted (in shares) | shares	323,500
Shares exercised (in shares) | shares	(9,500)
Shares canceled (in shares) | shares	(199,844)
Outstanding shares, Ending balance (in shares) | shares	1,378,550
Shares exercisable (in shares) | shares	907,667
Shares exercisable and expected to vest (in shares) | shares	1,314,500
Weighted Average Exercise Price
Weighted average exercise price, Outstanding beginning balance (in usd per share)	$ 7.41
Weighted average exercise price granted (in usd per share)	4.84
Weighted average exercise price exercised (in usd per share)	1.46
Weighted average exercise price canceled (in usd per share)	8.77
Weighted average exercise price, Outstanding ending balance (in usd per share)	6.65
Weighted average exercise price exercisable (in usd per share)	7.21
Weighted average exercise price exercisable and expected to vest (in usd per share)	$ 6.69
Share-based Compensation Arrangement by Share-based Payment Award, Options, Additional Disclosures [Abstract]
Weighted average remaining contractual life exercisable (in years)	4 years 5 months 5 days
Weighted average remaining contractual life exercisable and expected to vest (in years)	5 years 10 months 24 days
Aggregate intrinsic value exercisable | $	$ 0.0
Aggregate intrinsic value exercisable and expected to vest | $	$ 0.0
Minimum
Price Per Share
Outstanding price per share, Beginning balance (in usd per share)	$ 1.46
Price per share granted (in usd per share)	3.31
Price per share exercised (in usd per share)	1.46
Price per share canceled (in usd per share)	1.46
Outstanding price per share, Ending balance (in usd per share)	2.39
Price per share exercisable (in usd per share)	2.39
Price per share exercisable and expected to vest (in usd per share)	2.39
Maximum
Price Per Share
Outstanding price per share, Beginning balance (in usd per share)	14.66
Price per share granted (in usd per share)	6.26
Price per share canceled (in usd per share)	14.66
Outstanding price per share, Ending balance (in usd per share)	14.66
Price per share exercisable (in usd per share)	14.66
Price per share exercisable and expected to vest (in usd per share)	$ 14.66