Note 15 - Stockholders' Equity - Dividends Declared (Details) - $ / shares	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Common Shares (in dollars per share)	$ 0.23000	$ 0.22000	$ 0.69000	$ 0.61000
Series L Preferred Stock [Member]
Preferred Shares (in dollars per share)	0.32031	0.32031	0.96093	0.96093
Series M Preferred Stock [Member]
Preferred Shares (in dollars per share)	$ 0.32813	$ 0.32813	$ 0.98439	$ 0.98439