Condensed Consolidated Balance Sheets (Current Period Unaudited) (Parentheticals) - $ / shares	Mar. 31, 2024	Dec. 31, 2023
Preferred stock, shares authorized (in shares)	1,000,000
Series D Preferred Stock [Member]
Preferred stock, par value (in dollars per share)	$ 0.01	$ 0.01
Preferred stock, shares authorized (in shares)	1,000,000	1,000,000
Preferred stock, shares issued (in shares)	890,946	890,946
Preferred stock, shares outstanding (in shares)	890,946	890,946
Preferred stock, liquidation preference (in dollars per share)	$ 25	$ 25
Common Class A [Member]
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, shares authorized (in shares)	100,000,000	100,000,000
Common stock, shares issued (in shares)	12,429,139	12,265,061
Common stock, shares outstanding (in shares)	12,429,139	12,265,061