Note 2 - Summary of Significant Accounting Policies (Details) - Earnings Per Common Share: (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Earnings Per Common Share: [Abstract]
Net income, as reported (in Dollars)	$ 11,057	$ 11,201	$ 11,685	$ 10,296	$ 11,948	$ 9,421	$ 9,627	$ 6,756	$ 44,239	$ 37,752	$ 34,331
Divided by:
Weighted average common shares outstanding	29,343	29,772	30,059	29,984	29,762	29,773	30,213	30,449	29,788	30,047	30,402
Weighted average common stock equivalents									29	26	31
Total weighted average common shares outstanding and common stock equivalents	29,366	29,796	30,090	30,022	29,802	29,805	30,235	30,481	29,817	30,073	30,433
Basic earnings per common share (in Dollars per share)	$ 0.38	$ 0.38	$ 0.39	$ 0.34	$ 0.40	$ 0.32	$ 0.32	$ 0.22	$ 1.49	$ 1.26	$ 1.13
Diluted earnings per common share (in Dollars per share)	$ 0.38	$ 0.38	$ 0.39	$ 0.34	$ 0.40	$ 0.32	$ 0.32	$ 0.22	$ 1.48	$ 1.26	$ 1.13
Dividend Payout ratio									40.30%	41.30%	46.00%