Note 3 - Investment Securities Available for Sale (Detail) (USD $)	12 Months Ended
Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Percent of Debt Instruments Rated AAA	99.00%
Percent of Debt Instruments Rated A	1.00%
Unrealized Gain as Percent of Amortized Cost	3.20%
Debt Securities Weighted Average Duration	3 years 292 days
Federal Home Loan Bank Stock and Federal Reserve Bank Stock	$ 10,694,000	$ 10,242,000
Available-for-sale Securities, Gross Realized Gains	941,000,000	1,400,000	1,400,000
Available-for-sale Securities, Gross Realized Losses	251,000		42,000
Proceeds from Sale and Maturity of Marketable Securities	77,100,000	85,900,000	73,300,000
Available-for-sale Securities Pledged as Collateral	$ 220,100,000

The cash inflow associated with the aggregate amount received by the entity through sale or maturity of marketable securities (held-to-maturity or available-for-sale) during the period.

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

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Reference 2: 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-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009.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 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

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-URI http://asc.fasb.org/extlink&oid=6516133

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

-Publisher FASB

-Name Accounting Standards Codification

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-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009.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 6: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 95

-Paragraph 16

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-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009.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.

+ Details