Note 6 - Investment Securities (Detail) - The Amortized Costs And Estimated Fair Value Of The Securities Portfolio (USD $) In Thousands, unless otherwise specified	Sep. 30, 2012	Dec. 31, 2011
Available For Sale
Available for Sale Securities - Amortized Cost	$ 582,159	$ 583,951
Available for Sale Securities - Gross Unrealized Losses	1,400
Available for Sale Securities - Estimated Fair Value	600,556	597,819
Held To Maturity
Held to Maturity Securities - Amortized Cost	875	875
Held to Maturity Securities - Estimated Fair Value	1,008	974
US States and Political Subdivisions Debt Securities [Member]
Held To Maturity
Held to Maturity Securities - Amortized Cost	875	875
Held to Maturity Securities - Gross Unrealized Gains	133	99
Held to Maturity Securities - Estimated Fair Value	1,008	974
US Government-sponsored Enterprises Debt Securities [Member]
Available For Sale
Available for Sale Securities - Amortized Cost	74,407	95,770
Available for Sale Securities - Gross Unrealized Gains	293	408
Available for Sale Securities - Gross Unrealized Losses	2	15
Available for Sale Securities - Estimated Fair Value	74,698	96,163
US States and Political Subdivisions Debt Securities [Member]
Available For Sale
Available for Sale Securities - Amortized Cost	100,192	80,801
Available for Sale Securities - Gross Unrealized Gains	5,417	3,903
Available for Sale Securities - Gross Unrealized Losses	36	85
Available for Sale Securities - Estimated Fair Value	105,573	84,619
Residential Mortgage Backed Securities [Member]
Available For Sale
Available for Sale Securities - Amortized Cost	400,240	397,675
Available for Sale Securities - Gross Unrealized Gains	13,983	11,384
Available for Sale Securities - Gross Unrealized Losses	38	196
Available for Sale Securities - Estimated Fair Value	414,185	408,863
Mutual Funds And Equity Securities [Member]
Available For Sale
Available for Sale Securities - Amortized Cost	579	1,601
Available for Sale Securities - Gross Unrealized Gains	33
Available for Sale Securities - Estimated Fair Value	612	1,601
Corporate Debt Securities [Member]
Available For Sale
Available for Sale Securities - Amortized Cost	6,741	7,901
Available for Sale Securities - Gross Unrealized Gains	46
Available for Sale Securities - Gross Unrealized Losses	1,299	1,537
Available for Sale Securities - Estimated Fair Value	5,488	6,364
Total [Member]
Available For Sale
Available for Sale Securities - Amortized Cost	582,159	583,951
Available for Sale Securities - Gross Unrealized Gains	19,772	15,701
Available for Sale Securities - Gross Unrealized Losses	1,375	1,833
Available for Sale Securities - Estimated Fair Value	600,556	597,819
Commercial Mortgage Backed Securities [Member]
Available For Sale
Available for Sale Securities - Amortized Cost		203
Available for Sale Securities - Gross Unrealized Gains		6
Available for Sale Securities - Estimated Fair Value		$ 209

This item represents the cost of debt and equity securities, which are categorized neither as held-to-maturity nor trading, net of adjustments including accretion, amortization, collection of cash, previous other-than-temporary impairments recognized in earnings (less any cumulative-effect adjustments recognized, as defined), and fair value hedge accounting adjustments, if any.

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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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- Definition

This item represents the gross unrealized gains for securities, at a point in time, which are categorized neither as held-to-maturity nor trading securities.

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- Definition

For an unclassified balance sheet, this item represents investments in debt securities which are categorized as held-to-maturity. The held-to-maturity category is for those securities that the entity has the positive intent and ability to hold until maturity.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

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Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher AICPA

-Name Accounting Research Bulletin (ARB)

-Number 43

-Section A

-Paragraph 5

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Reference 3: http://www.xbrl.org/2003/role/presentationRef

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-Name Statement of Financial Accounting Standard (FAS)

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-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 4: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 115

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-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 5: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

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Reference 6: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 115

-Paragraph 9

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 7: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 115

-Paragraph 19

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 8: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 115

-Paragraph 8

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 9: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 115

-Paragraph 11

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 10: http://www.xbrl.org/2003/role/presentationRef

-Publisher AICPA

-Name Accounting Research Bulletin (ARB)

-Number 43

-Section A

-Paragraph 4

-Chapter 3

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 11: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 115

-Paragraph 7

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 12: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 942

-SubTopic 210

-Section S99

-Paragraph 1

-Subparagraph (SX 210.9-03.6)

-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

+ Details

- Definition

This item represents the aggregate fair value of investments in debt securities as of the balance sheet date and which are categorized as held-to-maturity.

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- Definition

As of the balance sheet date, the excess of fair value over carrying value (amortized cost) of a debt security categorized as held-to-maturity, exclusive of dividend or interest income recognized but not yet received and exclusive of any write-downs for other-than-temporary impairment. Such item represents the gross unrecognized holding gain.

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