Stockholders' Equity - Equity Offerings (Details)			3 Months Ended
	Jan. 29, 2019 USD ($) Institution $ / shares shares	Jan. 28, 2019 USD ($) $ / shares shares	Mar. 31, 2020 USD ($) shares	Mar. 31, 2019 USD ($)	Dec. 31, 2019 shares	Apr. 17, 2019 USD ($)
Stockholders' Equity
Common stock authorized (in shares) | shares			200,000,000		200,000,000
Preferred stock authorized (in shares) | shares			5,000,000		5,000,000
Issuance of common stock (in shares) | shares			4,800,000
Offering price (in dollars per share) | $ / shares	$ 1.00
Issuance of common stock, net of issuance costs			$ 3,551,000	$ 8,896,000
Wainwright
Stockholders' Equity
Percentage of aggregate gross proceeds paid		7.00%
Expenses paid		$ 50,000
Warrants to purchase shares of common stock | shares		500,000
Warrants term		5 years
Exercise price (in dollars per share) | $ / shares		$ 1.25
At-the-market sales facility - April 17, 2019 agreement
Stockholders' Equity
Offering amount						$ 50,000,000
Issuance of common stock, net of issuance costs			3,600,000
Remaining available for future issuances			$ 45,200,000
Private Placement
Stockholders' Equity
Issuance of common stock (in shares) | shares	10,000,000
Issuance of common stock, net of issuance costs	$ 9,200,000
Number of institutional investors | Institution	2