Note 9 - Fair Value Measurements (Details) - Assets measured at fair value on a recurring basis (USD $) In Thousands, unless otherwise specified	Jun. 30, 2013	Dec. 31, 2012
Investment securities available for sale:
Fair Value	$ 1,004,888	$ 825,636
Fair Value, Inputs, Level 1 [Member]
Investment securities available for sale:
Fair Value	50,880	57,424
Fair Value, Inputs, Level 2 [Member]
Investment securities available for sale:
Fair Value	$ 954,008	$ 768,212

Amount of investment in debt and equity securities categorized neither as held-to-maturity nor trading.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 320

-SubTopic 10

-Section 25

-Paragraph 1

-Subparagraph (b)

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 320

-SubTopic 10

-Section 50

-Paragraph 5

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 320

-SubTopic 10

-Section 45

-Paragraph 1

-URI http://asc.fasb.org/extlink&oid=6871852&loc=d3e26610-111562

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