Condensed Statements of Stockholders' Equity (Unaudited) - USD ($) $ in Thousands	February 2021 Public Offering [Member] Preferred Stock [Member]	February 2021 Public Offering [Member] Common Stock [Member]	February 2021 Public Offering [Member] Additional Paid-in Capital [Member]	February 2021 Public Offering [Member] Retained Earnings [Member]	February 2021 Public Offering [Member]	January 2022 Public Offering [Member] Preferred Stock [Member]	January 2022 Public Offering [Member] Common Stock [Member]	January 2022 Public Offering [Member] Additional Paid-in Capital [Member]	January 2022 Public Offering [Member] Retained Earnings [Member]	January 2022 Public Offering [Member]	Series D Preferred Stock [Member] Preferred Stock [Member]	Series D Preferred Stock [Member] Common Stock [Member]	Series D Preferred Stock [Member] Additional Paid-in Capital [Member]	Series D Preferred Stock [Member] Retained Earnings [Member]	Series D Preferred Stock [Member]	Preferred Stock [Member]	Common Stock [Member]	Additional Paid-in Capital [Member]	Retained Earnings [Member]	Total
Balance (in shares) at Dec. 31, 2020																52,369	4,246,306
Balance at Dec. 31, 2020																$ 0	$ 85	$ 380,332	$ (367,341)	$ 13,076
Issuance of common stock under officers and directors purchase plan and vesting of restricted stock units (in shares)																0	2,744
Issuance of common stock under officers and directors purchase plan and vesting of restricted stock units																$ 0	$ 0	0	0	0
Employee stock-based compensation																0	0	721	0	721
Accretion of Series A preferred stock dividends																0	0	(2,088)	0	(2,088)
Net and comprehensive loss																$ 0	$ 0	0	(7,504)	(7,504)
Issuance of common stock in public offerings, net of commissions and issuance costs (in shares)	0	500,000
Issuance of common stock in public offerings, net of commissions and issuance costs	$ 0	$ 10	$ 13,067	$ 0	$ 13,077
Conversion of preferred stock into common stock (in shares)																(93)	18,600
Conversion of preferred stock into common stock																$ 0	$ 0	0	0	0
Balance (in shares) at Jun. 30, 2021																52,276	4,767,650
Balance at Jun. 30, 2021																$ 0	$ 95	392,032	(374,845)	17,282
Balance (in shares) at Mar. 31, 2021																52,276	4,767,575
Balance at Mar. 31, 2021																$ 0	$ 95	392,773	(372,393)	20,475
Issuance of common stock under officers and directors purchase plan and vesting of restricted stock units (in shares)	0	75
Issuance of common stock under officers and directors purchase plan and vesting of restricted stock units	$ 0	$ 0	$ 0	$ 0	$ 0
Employee stock-based compensation																0	0	303	0	303
Accretion of Series A preferred stock dividends																0	0	(1,044)	0	(1,044)
Net and comprehensive loss																$ 0	$ 0	0	(2,452)	(2,452)
Balance (in shares) at Jun. 30, 2021																52,276	4,767,650
Balance at Jun. 30, 2021																$ 0	$ 95	392,032	(374,845)	17,282
Balance (in shares) at Dec. 31, 2021																56,451	4,778,263
Balance at Dec. 31, 2021																$ 0	$ 96	394,380	(384,753)	9,723
Employee stock-based compensation																0	0	88	0	88
Accretion of Series A preferred stock dividends																0	0	(2,254)	0	(2,254)
Net and comprehensive loss																$ 0	$ 0	0	(9,354)	$ (9,354)
Issuance of common stock in public offerings, net of commissions and issuance costs (in shares)						0	326,466				7,600	0								326,466
Issuance of common stock in public offerings, net of commissions and issuance costs						$ 0	$ 1	$ 395	$ 0	$ 396	$ 0	$ 0	$ 6,721	$ 0	$ 6,721
Conversion of preferred stock into common stock (in shares)																(7,600)	950,000
Conversion of preferred stock into common stock																$ 0	$ 1	0	0	$ 1
Issuance of common stock upon vesting of restricted stock units (in shares)																0	435
Issuance of common stock upon vesting of restricted stock units																$ 0	$ 0	0	0	0
Reclassifications and adjustments due to rounding impact from reverse stock split for fractional shares (in shares)																0	26,169
Reclassifications and adjustments due to rounding impact from reverse stock split for fractional shares																$ 0	$ (92)	92	0	0
Balance (in shares) at Jun. 30, 2022																56,451	6,081,333
Balance at Jun. 30, 2022																$ 0	$ 6	399,422	(394,107)	5,321
Balance (in shares) at Mar. 31, 2022																58,851	5,454,849
Balance at Mar. 31, 2022																$ 0	$ 5	400,118	(389,893)	10,230
Employee stock-based compensation																0	0	36	0	36
Accretion of Series A preferred stock dividends																0	0	(1,127)	0	(1,127)
Net and comprehensive loss																$ 0	$ 0	0	(4,214)	(4,214)
Issuance of common stock in public offerings, net of commissions and issuance costs (in shares)						0	326,466
Issuance of common stock in public offerings, net of commissions and issuance costs						$ 0	$ 1	$ 395	$ 0	$ 396
Conversion of preferred stock into common stock (in shares)																(2,400)	300,000
Conversion of preferred stock into common stock																$ 0	$ 0	0	0	0
Issuance of common stock upon vesting of restricted stock units (in shares)																0	18
Issuance of common stock upon vesting of restricted stock units																$ 0	$ 0	0	0	0
Balance (in shares) at Jun. 30, 2022																56,451	6,081,333
Balance at Jun. 30, 2022																$ 0	$ 6	$ 399,422	$ (394,107)	$ 5,321