Condensed Consolidated Balance Sheets (Unaudited) (Parentheticals) - USD ($) $ in Thousands	Mar. 31, 2023	Dec. 31, 2022
Statement of Financial Position [Abstract]
Accounts receivable, reserve	$ 3,244	$ 3,169
Vessels and vessel improvements, accumulated depreciation	268,743	261,725
Other fixed assets, accumulated depreciation	$ 1,665	$ 1,623
Preferred stock, par value (in dollars per share)	$ 0.01	$ 0.01
Preferred stock, shares authorized (in shares)	25,000,000	25,000,000
Preferred stock, shares issued (in shares)	0	0
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, shares authorized (in shares)	700,000,000	700,000,000
Common stock, shares issued (in shares)	13,065,060	13,003,702
Common stock outstanding (in shares)	13,065,060	13,003,702