Note 12 - Stockholders' Equity - Common Stock Dividend Policy (Details)	12 Months Ended
	Dec. 31, 2021 $ / shares
Quarterly Average Realized Price, Level 1 [Member]
Quarterly dividend per share (in dollars per share)	$ 0.0025
Annual dividend per share (in dollars per share)	0.01
Minimum annual component per share (in dollars per share)	0.015
Annualized dividends (in dollars per share)	0.025
Quarterly Average Realized Price, Level 2 [Member]
Quarterly dividend per share (in dollars per share)	0.0100
Annual dividend per share (in dollars per share)	0.04
Minimum annual component per share (in dollars per share)	0.015
Annualized dividends (in dollars per share)	0.055
Quarterly Average Realized Price, Level 3 [Member]
Quarterly dividend per share (in dollars per share)	0.0150
Annual dividend per share (in dollars per share)	0.06
Minimum annual component per share (in dollars per share)	0.015
Annualized dividends (in dollars per share)	0.075
Quarterly Average Realized Price, Level 4 [Member]
Quarterly dividend per share (in dollars per share)	0.0250
Annual dividend per share (in dollars per share)	0.10
Minimum annual component per share (in dollars per share)	0.015
Annualized dividends (in dollars per share)	0.115
Quarterly Average Realized Price, Level 5 [Member]
Quarterly dividend per share (in dollars per share)	0.0350
Annual dividend per share (in dollars per share)	0.14
Minimum annual component per share (in dollars per share)	0.015
Annualized dividends (in dollars per share)	0.155
Quarterly Average Realized Price, Level 6 [Member]
Quarterly dividend per share (in dollars per share)	0.0450
Annual dividend per share (in dollars per share)	0.18
Minimum annual component per share (in dollars per share)	0.015
Annualized dividends (in dollars per share)	0.195
Quarterly Average Realized Price, Level 7 [Member]
Quarterly dividend per share (in dollars per share)	0.0550
Annual dividend per share (in dollars per share)	0.22
Minimum annual component per share (in dollars per share)	0.015
Annualized dividends (in dollars per share)	$ 0.235