Commitments and Contingencies - Settlement of Underwriter Fee (Details) - USD ($)	3 Months Ended	12 Months Ended
	Mar. 31, 2020	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Aug. 28, 2018
Number of pre-funded warrants issued		22,048,278	20,637,761
Convertible preferred stock					9,580
Underwriter
Underwriters settlement fee	$ 387,000
Payments of underwriters settlement fee		$ 185,000	$ 202,000
Number of pre-funded warrants issued				1,096
Convertible preferred stock		100,780
Exercise price (in dollars per share)		$ 2.50
Issuance of common stock (In shares)		100,000
Amount of shares issued		$ 45,000