Note 4 - Earnings Per Share Calculation (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Numerator for basic and diluted earnings per share – Net income available to common shareholders	$ 10,817	$ 19,576	$ 13,212	$ 36,357
Denominator for basic earnings per share – weighted average shares outstanding (in shares)	40,250	40,275	40,402	40,171
Effect of dilutive securities–Employee and director stock options and restricted share awards (in shares)	528	797	512	858
Denominator for diluted earnings per share – adjusted weighted average shares outstanding and assumed conversions (in shares)	40,778	41,072	40,914	41,029
Basic earnings per common share (in dollars per share)	$ 0.27	$ 0.49	$ 0.33	$ 0.91
Diluted earnings per common share and common share equivalents (in dollars per share)	$ 0.27	$ 0.48	$ 0.32	$ 0.89