Note 2 - Earnings Per Common Share - Basic and Diluted Earnings Per Common Share (Details) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Net income	$ 8,410	$ 7,652	$ 26,955	$ 20,865
Basic earnings per common share - weighted-average shares (in shares)	33,622	33,403	33,555	33,371
Effect of dilutive stock options (in shares)	224	289	261	301
Diluted earnings per common share - weighted-average shares and assumed conversions (in shares)	33,846	33,692	33,816	33,672
Basic earnings per common share (in dollars per share)	$ 0.25	$ 0.23	$ 0.80	$ 0.63
Diluted earnings per common share (in dollars per share)	$ 0.25	$ 0.23	$ 0.80	$ 0.62