Note 2 - Investment Securities - Schedule of Investment Securities (Details) - USD ($) $ in Thousands	Mar. 31, 2017	Dec. 31, 2016
Available for sale securities, amortized cost	$ 349,332	$ 331,267
Available for sale securities, gross unrealized gains	144	94
Available for sale securities, gross unrealized losses	(7,544)	(7,703)
Available for sale securities, fair value	341,932	323,658
US Government Agencies Debt Securities [Member]
Available for sale securities, amortized cost	342,828	326,694
Available for sale securities, gross unrealized gains	109	76
Available for sale securities, gross unrealized losses	(7,486)	(7,673)
Available for sale securities, fair value	335,451	319,097
US States and Political Subdivisions Debt Securities [Member]
Available for sale securities, amortized cost	4,444	4,573
Available for sale securities, gross unrealized gains	35	18
Available for sale securities, gross unrealized losses	(23)	(30)
Available for sale securities, fair value	4,456	$ 4,561
Corporate Debt Securities [Member]
Available for sale securities, amortized cost	2,060
Available for sale securities, gross unrealized gains
Available for sale securities, gross unrealized losses	(35)
Available for sale securities, fair value	$ 2,025

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
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Amount before tax of unrealized gain in accumulated other comprehensive income (AOCI) on investments in debt and equity securities classified as available-for-sale.

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Amount before tax of unrealized loss in accumulated other comprehensive income (AOCI) on investments in debt and equity securities classified as available-for-sale.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
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-Name Accounting Standards Codification
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