Note 3 - Earnings Per Share - Earnings Per Common Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands		3 Months Ended		9 Months Ended
		Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Net Income		$ 10,179	$ 10,634	$ 35,164	$ 50,630
Divided by:
Weighted average common shares outstanding (in shares)		29,120	28,861	29,092	28,993
Weighted average common stock equivalents (in shares)		1	14	2	13
Total weighted average common shares outstanding and common stock equivalents (in shares)		29,121	28,875	29,094	29,006
Basic earnings per common share (in dollars per share)		$ 0.35	$ 0.37	$ 1.21	$ 1.75
Diluted earnings per common share (in dollars per share)	[1]	$ 0.35	$ 0.37	$ 1.21	$ 1.75
Dividend payout ratio		51.40%	45.90%	44.60%	29.10%

[1] For the three and nine months ended September 30, 2017 and 2016, there were no stock options that were anti-dilutive.