Note 6 - Investment Securities (Details) - USD ($) $ in Thousands	Jun. 30, 2015	Dec. 31, 2014
Note 6 - Investment Securities (Details) [Line Items]
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax	$ 3,235	$ 3,004
Available-for-sale Securities	618,297	626,388
Single Issuer Corporate Debt Security [Member]
Note 6 - Investment Securities (Details) [Line Items]
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax	509	$ 354
Available-for-sale Securities	$ 5,400

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)

-URI http://asc.fasb.org/extlink&oid=51813488&loc=d3e22054-111558

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 320

-SubTopic 10

-Section 50

-Paragraph 5

-Subparagraph (aa)

-URI http://asc.fasb.org/extlink&oid=27724398&loc=d3e27232-111563

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=49167202&loc=d3e26610-111562

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
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