Note 3 - Investment Securities (Details) - Interest Income from Investment Securities (USD $) In Thousands, unless otherwise specified	3 Months Ended	9 Months Ended
Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Interest Income from Investment Securities [Abstract]
Taxable	$ 6,348	$ 5,502	$ 17,907	$ 16,626
Tax-exempt	6,423	7,338	20,143	22,368
Total interest income from investment securities	$ 12,771	$ 12,840	$ 38,050	$ 38,994

Amount of operating dividend and interest income, including amortization and accretion of premiums and discounts, on securities.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 320

-SubTopic 10

-Section 35

-Paragraph 4

-URI http://asc.fasb.org/extlink&oid=27723805&loc=d3e24721-111560

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 04

-Paragraph 2, 3

-Article 9

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 942

-SubTopic 225

-Section S99

-Paragraph 1

-Subparagraph (SX 210.9-04.2,3)

-URI http://asc.fasb.org/extlink&oid=6879574&loc=d3e536633-122882

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Amount of operating interest income, including amortization and accretion of premiums and discounts, on securities subject to state, federal and other income tax.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 942

-SubTopic 225

-Section S99

-Paragraph 1

-Subparagraph (SX 210.9-04.2)

-URI http://asc.fasb.org/extlink&oid=6879574&loc=d3e536633-122882

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

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-Name Regulation S-X (SX)

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-Section 04

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