Note 3 - Earnings Per Share - Earnings Per Common Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands		3 Months Ended
		Mar. 31, 2017	Mar. 31, 2016
Net income		$ 12,260	$ 9,561
Divided by:
Weighted average common shares outstanding (in shares)		29,019	29,097
Weighted average common stock equivalents (in shares)		4	14
Total weighted average common shares outstanding and common stock equivalents (in shares)		29,023	29,111
Basic earnings per common share (in dollars per share)		$ 0.42	$ 0.33
Diluted earnings per common share (in dollars per share)	[1]	$ 0.42	$ 0.33
Dividend payout ratio		42.90%	51.50%

[1] For the three months ended March 31, 2017 and 2016, there were no stock options that were anti-dilutive.