Note 5 - Fair Value Measurements (Detail) - Available For Sale Investment Securities Measured At Fair Value On A Recurring Basis (USD $) In Thousands, unless otherwise specified	Jun. 30, 2012	Dec. 31, 2011
Available For Sale Investment Securities	$ 616,856	$ 597,819
Obligations Of US Government Sponsored Entities [Member] \| Fair Value, Inputs, Level 2 [Member]
Available For Sale Investment Securities	76,539	96,163
Obligations Of US Government Sponsored Entities [Member]
Available For Sale Investment Securities	76,539	96,163
Obligations Of States And Political Subdivisions [Member] \| Fair Value, Inputs, Level 2 [Member]
Available For Sale Investment Securities	102,955	84,619
Obligations Of States And Political Subdivisions [Member]
Available For Sale Investment Securities	102,955	84,619
Mortgage Backed Securities Residential [Member] \| Fair Value, Inputs, Level 2 [Member]
Available For Sale Investment Securities	429,344	408,863
Mortgage Backed Securities Residential [Member]
Available For Sale Investment Securities	429,344	408,863
Mortgage Backed Securities Commercial [Member] \| Fair Value, Inputs, Level 2 [Member]
Available For Sale Investment Securities	30	209
Mortgage Backed Securities Commercial [Member]
Available For Sale Investment Securities	30	209
Mutual Funds And Equity Securities [Member] \| Fair Value, Inputs, Level 1 [Member]
Available For Sale Investment Securities	1,454	1,601
Mutual Funds And Equity Securities [Member]
Available For Sale Investment Securities	1,454	1,601
Corporate Debt Securities [Member] \| Fair Value, Inputs, Level 2 [Member]
Available For Sale Investment Securities	6,534	6,364
Corporate Debt Securities [Member]
Available For Sale Investment Securities	6,534	6,364
Fair Value, Inputs, Level 1 [Member]
Available For Sale Investment Securities	1,454	1,601
Fair Value, Inputs, Level 2 [Member]
Available For Sale Investment Securities	$ 615,402	$ 596,218

- 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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