Note 18 - Subsequent Event (Details Textual) - $ / shares	1 Months Ended	12 Months Ended
	Feb. 28, 2021	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Common Stock, Dividends, Per Share, Declared (in dollars per share)		$ 2.00	$ 1.60	$ 1.20
Quarterly Cash Dividends [Member]
Common Stock, Dividends, Per Share, Declared (in dollars per share)		$ 0.50
Quarterly Cash Dividends [Member] | Subsequent Event [Member]
Common Stock, Dividends, Per Share, Declared (in dollars per share)	$ 0.60