Note 4 - Earnings Per Share - Earnings Per Share Calculation (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Numerator for basic and diluted earnings per share – Net income available to common shareholders	$ 45,333	$ 23,107
Denominator for basic earnings per share – weighted average shares outstanding (in shares)	55,567	54,727
Employee and director stock options and restricted share awards (in shares)	2,167	1,262
Denominator for diluted earnings per share – adjusted weighted average shares outstanding and assumed conversions (in shares)	57,734	55,989
Basic earnings per common share (in dollars per share)	$ 0.82	$ 0.42
Diluted earnings per common share and common share equivalents (in dollars per share)	$ 0.79	$ 0.41