Stock Plans and Stock Based Compensation - Narrative (Details)		1 Months Ended	3 Months Ended		12 Months Ended
	May 23, 2019 shares	Jan. 31, 2019 $ / shares shares	Mar. 31, 2020 USD ($) purchase_period plan $ / shares shares	Mar. 31, 2019 USD ($) $ / shares shares	Dec. 31, 2016 purchase_period	Dec. 31, 2019 $ / shares shares
Deferred Compensation Arrangement with Individual, Share-based Payments [Line Items]
Number of shareholder-approved, share-based compensation plans | plan			2
Number of options granted (shares)			3,258,150
Exercise price (USD per share) | $ / shares			$ 1.85
Awarded (shares)			140,000
Weighted average grant-date fair values of stock options (USD per share) | $ / shares			$ 0.76	$ 0.76
Unrecognized compensation cost, net of estimated forfeitures | $			$ 4,500,000
Unrecognized compensation cost, weighted average period for recognition			2 years 10 months 5 days
Intrinsic values of employee stock options exercised | $			$ 0	$ 0
Compensation expense related to employee and director stock option grants | $			$ 625,000	$ 651,000
Restricted Stock
Deferred Compensation Arrangement with Individual, Share-based Payments [Line Items]
Exercise price (USD per share) | $ / shares			$ 0.00
Awarded (shares)			0
Outstanding shares (shares)			20,624			30,937
Weighted average fair value (USD per share) | $ / shares			$ 3.45			$ 3.45
Fair value | $			$ 100,000
Stock options outstanding
Deferred Compensation Arrangement with Individual, Share-based Payments [Line Items]
Vesting period of options (years)			4 years
Officers | Restricted Stock
Deferred Compensation Arrangement with Individual, Share-based Payments [Line Items]
Vesting period of options (years)			4 years
Officers and Non-Employee Directors | Restricted Stock
Deferred Compensation Arrangement with Individual, Share-based Payments [Line Items]
Unrecognized compensation cost, net of estimated forfeitures | $			$ 100,000
Unrecognized compensation cost, weighted average period for recognition			1 year 9 months 22 days
Tranche one
Deferred Compensation Arrangement with Individual, Share-based Payments [Line Items]
Percentage of vested shares which are exercisable under stock option			25.00%
Tranche two
Deferred Compensation Arrangement with Individual, Share-based Payments [Line Items]
Percentage of vested shares which are exercisable under stock option			6.25%
Amended and Restated 2010 Stock Incentive Plan
Deferred Compensation Arrangement with Individual, Share-based Payments [Line Items]
Shares authorized (shares)			10,890,000
Shares awarded under plan (shares)			1,395,833
Amended and Restated 2010 Stock Incentive Plan | Stock Options, or Stock Appreciation Rights
Deferred Compensation Arrangement with Individual, Share-based Payments [Line Items]
Expiration period (years)			10 years
Shares removed from pool (shares per share)			1
Amended and Restated 2010 Stock Incentive Plan | Restricted Stock, RSUs, Other Stock-Based Awards, or Performance Awards
Deferred Compensation Arrangement with Individual, Share-based Payments [Line Items]
Shares removed from pool (shares per share)			1.3
Purchase price of common stock (percentage of fair market value)			100.00%
Amended and Restated 2010 Stock Incentive Plan | Employee Stock
Deferred Compensation Arrangement with Individual, Share-based Payments [Line Items]
Additional shares authorized (shares)	4,700,000
2010 Plan
Deferred Compensation Arrangement with Individual, Share-based Payments [Line Items]
Number of options granted (shares)			2,538,150
2010 Plan | Officers
Deferred Compensation Arrangement with Individual, Share-based Payments [Line Items]
Number of options granted (shares)		1,520,000
Vesting period of options (years)		4 years
Exercise price (USD per share) | $ / shares		$ 1.26
2010 Plan | Non-Employee Directors
Deferred Compensation Arrangement with Individual, Share-based Payments [Line Items]
Number of options granted (shares)			0	720,000
Exercise price (USD per share) | $ / shares				$ 1.26
2010 Plan | Tranche one
Deferred Compensation Arrangement with Individual, Share-based Payments [Line Items]
Options granted to employees (shares)			878,150
Percentage of vested shares which are exercisable under stock option			25.00%
2010 Plan | Tranche one | Officers
Deferred Compensation Arrangement with Individual, Share-based Payments [Line Items]
Percentage of vested shares which are exercisable under stock option		25.00%
2010 Plan | Tranche two
Deferred Compensation Arrangement with Individual, Share-based Payments [Line Items]
Percentage of vested shares which are exercisable under stock option			6.25%
2010 Plan | Tranche two | Officers
Deferred Compensation Arrangement with Individual, Share-based Payments [Line Items]
Percentage of vested shares which are exercisable under stock option		6.25%
Employee Stock Purchase Plan | Employee Stock
Deferred Compensation Arrangement with Individual, Share-based Payments [Line Items]
Shares authorized (shares)			2,000,000
Purchase price of common stock (percentage of fair market value)			85.00%
Enrollment period (years)			2 years
Number of purchase periods per year | purchase_period			4		2
Stock plan offering period (months)					6 months
Stock issued under employee stock purchase plans (shares)			0
Stock available under ESPPs (shares)			1,677,934
Compensation expense related to employee and director stock option grants | $			$ 0