Note 4 - Earnings Per Share - Earnings Per Share Calculation (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Numerator for basic and diluted earnings per share – Net income available to common shareholders	$ 14,880	$ 19,883	$ 28,092	$ 56,240
Basic (in shares)	39,617	40,361	40,138	40,235
Employee and director stock options and restricted share awards (in shares)	657	775	560	830
Denominator for diluted earnings per share – adjusted weighted average shares outstanding and assumed conversions (in shares)	40,274	41,136	40,698	41,065
Basic earnings per common share (in dollars per share)	$ 0.38	$ 0.49	$ 0.70	$ 1.40
Diluted earnings per common share and common share equivalents (in dollars per share)	$ 0.37	$ 0.48	$ 0.69	$ 1.37