Note 6 - Fair Value Measurements (Detail) - Available For Sale Investment Securities Measured At Fair Value On A Recurring Basis (USD $) In Thousands, unless otherwise specified	Mar. 31, 2013	Dec. 31, 2012
Available For Sale Investment Securities	$ 569,302	$ 573,108
US Government-sponsored Enterprises Debt Securities [Member] \| Fair Value, Inputs, Level 2 [Member]
Available For Sale Investment Securities	82,940	76,095
US Government-sponsored Enterprises Debt Securities [Member]
Available For Sale Investment Securities	82,940	76,095
US States and Political Subdivisions Debt Securities [Member] \| Fair Value, Inputs, Level 2 [Member]
Available For Sale Investment Securities	126,490	118,755
US States and Political Subdivisions Debt Securities [Member]
Available For Sale Investment Securities	126,490	118,755
Residential Mortgage Backed Securities [Member] \| Fair Value, Inputs, Level 2 [Member]
Available For Sale Investment Securities	351,818	370,439
Residential Mortgage Backed Securities [Member]
Available For Sale Investment Securities	351,818	370,439
Corporate Debt Securities [Member] \| Fair Value, Inputs, Level 2 [Member]
Available For Sale Investment Securities	6,536	5,826
Corporate Debt Securities [Member]
Available For Sale Investment Securities	6,536	5,826
Mutual Funds And Equity Securities [Member] \| Fair Value, Inputs, Level 1 [Member]
Available For Sale Investment Securities	1,518	1,993
Mutual Funds And Equity Securities [Member]
Available For Sale Investment Securities	1,518	1,993
Fair Value, Inputs, Level 1 [Member]
Available For Sale Investment Securities	1,518	1,993
Fair Value, Inputs, Level 2 [Member]
Available For Sale Investment Securities	$ 567,784	$ 571,115

- Definition

This element represents the portion of the balance sheet assertion valued at fair value by the entity whether such amount is presented as a separate caption or as a parenthetical disclosure. Additionally, this element may be used in connection with the fair value disclosures required in the footnote disclosures to the financial statements. The element may be used in both the balance sheet and disclosure in the same submission. This item represents Available-for-sale Securities which consist of all investments in certain debt and equity securities neither classified as trading or held-to-maturity securities. A debt security represents a creditor relationship with an enterprise. Debt securities include, among other items, US Treasury securities, US government securities, municipal securities, corporate bonds, convertible debt, commercial paper, and all securitized debt instruments. An equity security represents an ownership interest in an enterprise or the right to acquire or dispose of an ownership interest in an enterprise at fixed or determinable prices. Equity securities include, among other things, common stock, certain preferred stock, warrant rights, call options, and put options, but do not include convertible debt. An entity may opt to provide the reader with additional narrative text to better understand the nature of investments in debt and equity securities which are categorized as Available-for-sale.

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