Note 11 - Earnings Per Common Share - Earnings Per Common Share and Diluted 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	$ 15,049	$ 14,226
Average Common Shares Outstanding (in shares)	26,171	25,445
Basic earnings (in dollars per share)	$ 0.58	$ 0.56
Add common stock equivalents for options (in shares)	158	23
Weighted average number of common shares outstanding - diluted (denominator) (in shares)	26,329	25,468
Diluted earnings (in dollars per share)	$ 0.57	$ 0.56