Description of the Business and Liquidity (Details) - USD ($)		3 Months Ended		12 Months Ended
	Dec. 13, 2019	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2019	Dec. 31, 2018
Liquidity
Accumulated deficit		$ 235,574,000	$ 181,453,000	$ 235,574,000	$ 181,453,000
Net proceeds from issuance of common stock and preferred stock		65,700,000
2017 Equity Distribution Agreement
Liquidity
Net proceeds from issuance of common stock				2,100,000
Series A Convertible Preferred Stock | Private placement
Liquidity
Issuance of Series A convertible preferred stock (in shares)		$ 30,000		$ 30,000
Common Stock
Liquidity
Issuance of stock (in shares)	32,200,000
Net proceeds from issuance of common stock	$ 37,400,000
Issuance of shares under equity distribution agreement (in shares)				1,692,289
Common Stock | Public Offering
Liquidity
Issuance of stock (in shares)		32,200,000	12,000,000	32,200,000	12,000,000
Net proceeds from issuance of common stock			$ 42,100,000
Common Stock | 2017 Equity Distribution Agreement
Liquidity
Net proceeds from issuance of common stock		$ 2,100,000
Issuance of shares under equity distribution agreement (in shares)		1,692,289		1,692,289	0