Stockholders' Equity, Issuance of Common Stock (Details) - USD ($)		12 Months Ended
	May 23, 2019	Dec. 31, 2021	Dec. 31, 2020
Stockholders' Equity [Abstract]
Common stock, shares authorized (in shares)		150,000,000	100,000,000
Undesignated stock, shares authorized (in shares)		20,000,000	20,000,000
Convertible preferred stock, shares authorized (in shares)		1,742,500	1,742,500
Issuance of common stock (in shares)		59,341,305	57,077,055
Net proceeds from issuance of common stock		$ 6,814,000	$ 263,000
2020 Market Agreement [Member]
Stockholders' Equity [Abstract]
Aggregate offering price		$ 40,000,000.0
Percentage of commission rate to be paid to sales agent		3.00%
Issuance of common stock (in shares)		845,214	14,452
Net proceeds from issuance of common stock		$ 3,864,000	$ 44,000
Common Stock [Member]
Stockholders' Equity [Abstract]
Convertible preferred stock, shares authorized (in shares)		12,748,500
Issuance of common stock (in shares)	10,488,161
Net proceeds from issuance of common stock	$ 44,900,000
Series A 12% Convertible Preferred Stock [Member]
Stockholders' Equity [Abstract]
Convertible preferred stock, shares authorized (in shares)		1,742,500
Series B-1 Convertible Preferred Stock [Member]
Stockholders' Equity [Abstract]
Convertible preferred stock, shares authorized (in shares)		900,000
Series B-2 Convertible Preferred Stock [Member]
Stockholders' Equity [Abstract]
Convertible preferred stock, shares authorized (in shares)		2,100,000
Series B-3 Convertible Preferred Stock [Member]
Stockholders' Equity [Abstract]
Convertible preferred stock, shares authorized (in shares)		2,508,000
Series C 6% Super Dividend Redeemable Convertible Preferred Stock [Member]
Stockholders' Equity [Abstract]
Convertible preferred stock, shares authorized (in shares)		1,000