Note 22 - Parent Company Only Financial Information (Details) - Condensed Statements of Cash Flows for the Holding Company: (USD $)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Operating activities:
Net income	$ 37,752,000	$ 34,331,000	$ 35,348,000
Adjustments to reconcile net income to net cash providedby operating activities:
Net gain on sale of securities	(3,021,000)	(47,000)
Deferred income tax provision	(682,000)	(804,000)	685,000
Fair value adjustments for financial assets and financial liabilities	2,521,000	(55,000)	(1,960,000)
Stock based compensation expense	3,412,000	3,260,000	2,686,000
Net cash provided by operating activities	74,435,000	71,097,000	64,720,000
Investing activities:
Purchases of securities available for sale	(458,596,000)	(311,654,000)	(157,741,000)
Proceeds from sales and calls of securities available for sale	194,009,000	12,637,000	8,000,000
Net cash provided by (used in) investing activities	(326,024,000)	(197,988,000)	22,693,000
Financing activities:
Purchase of treasury stock	(14,151,000)	(5,551,000)	(7,722,000)
Cash dividends paid	(15,618,000)	(15,817,000)	(15,910,000)
Stock options exercised	533,000	885,000	2,040,000
Net cash used in financing activities	244,649,000	111,595,000	(79,481,000)
Net (decrease) increase in cash and cash equivalents	(6,940,000)	(15,296,000)	7,932,000
Cash and cash equivalents, beginning of year	40,425,000	55,721,000	47,789,000
Cash and cash equivalents, end of year	33,485,000	40,425,000	55,721,000
Holding Company [Member]
Operating activities:
Net income	37,752,000	34,331,000	35,348,000
Adjustments to reconcile net income to net cash providedby operating activities:
Equity in undistributed earnings of the Bank	(21,450,000)	(14,835,000)	(14,526,000)
Net gain on sale of securities	(17,000)
Deferred income tax provision	(2,348,000)	858,000	3,003,000
Fair value adjustments for financial assets and financial liabilities	5,475,000	(1,991,000)	(5,725,000)
Stock based compensation expense	3,068,000	3,105,000	2,720,000
Net change in operating assets and liabilities	1,746,000	1,287,000	1,541,000
Net cash provided by operating activities	24,226,000	22,755,000	22,361,000
Investing activities:
Purchases of securities available for sale	(23,000)	(29,000)	(37,000)
Proceeds from sales and calls of securities available for sale	517,000
Net cash provided by (used in) investing activities	494,000	(29,000)	(37,000)
Financing activities:
Purchase of treasury stock	(14,151,000)	(5,622,000)	(7,722,000)
Cash dividends paid	(15,618,000)	(15,817,000)	(15,910,000)
Stock options exercised	533,000	956,000	2,040,000
Net cash used in financing activities	(29,236,000)	(20,483,000)	(21,592,000)
Net (decrease) increase in cash and cash equivalents	(4,516,000)	2,243,000	732,000
Cash and cash equivalents, beginning of year	21,041,000	18,798,000	18,066,000
Cash and cash equivalents, end of year	$ 16,525,000	$ 21,041,000	$ 18,798,000