Note 11 - Preferred Stock (Details Textual)				12 Months Ended		36 Months Ended
	Jan. 19, 2021 shares	Nov. 26, 2019	Nov. 12, 2019 shares	Dec. 31, 2021 USD ($) $ / shares shares	Dec. 31, 2020 USD ($) shares	Dec. 31, 2021 USD ($) $ / shares shares	Mar. 31, 2021 shares	Jan. 31, 2021 shares	Dec. 16, 2020 shares	Dec. 15, 2020 shares
Class of Warrant or Right, Number of Securities Called by Warrants or Rights (in shares)				2	2	2
Warrants Issued Upon Conversion of Term Loan with CRG [Member]
Class of Warrant or Right, Number of Securities Called by Warrants or Rights (in shares)			989,379
Conversion of Term Loan with CRG Into Series B Convertible Preferred Stock [Member]
Debt Conversion, Converted Instrument, Shares Issued (in shares)			31,300
Series A Preferred Stock [Member]
Preferred Stock, Shares Outstanding, Ending Balance (in shares)				0		0			0
Preferred Stock, Shares Authorized (in shares)										547,345
Convertible Preferred Stock, Shares Issued upon Conversion (in shares)				1		1
Series B Preferred Stock [Member]
Preferred Stock, Shares Outstanding, Ending Balance (in shares)				40,504	35,819	40,504
Preferred Stock, Shares Authorized (in shares)				10,000,000	10,000,000	10,000,000
Preferred Stock, Dividend Rate, Percentage		12.50%
Preferred Stock Dividends, Shares (in shares)				4,685	4,141	9,204
Dividends, Preferred Stock, Cash | $				$ 6,400	$ 8,000	$ 17,000
Convertible Preferred Stock, Shares Issued upon Conversion (in shares)				2,647,320	2,341,111	2,647,320
Conversion of Stock Exchange Ratio				65.36
Preferred Stock, Liquidation Preference Per Share (in dollars per share) | $ / shares				$ 1,000		$ 1,000
Conversion of Stock, Conversion Rate (in dollars per share) | $ / shares				$ 15.30		$ 15.30
Series C Preferred Stock [Member]
Preferred Stock, Shares Outstanding, Ending Balance (in shares)				0	0	0	0	0
Preferred Stock, Shares Authorized (in shares)				10,000,000	10,000,000	10,000,000
Convertible Preferred Stock, Shares Issued upon Conversion (in shares)				1		1
Conversion of Stock Exchange Ratio				1
Series C Preferred Stock [Member] | January 2021 Offering [Member]
Convertible Preferred Stock, Shares Issued upon Conversion (in shares)							1
Stock Issued During Period, Shares, New Issues (in shares)	2,450,880