Note 2 - Investment Securities (Details) - Investment Securities - USD ($) $ in Thousands	Sep. 30, 2015	Dec. 31, 2014
U.S. Government Agencies
Available for sale securities, amortized cost	$ 275,217	$ 281,935
Available for sale securities, gross unrealized gains	529	183
Available for sale securities, gross unrealized losses	(4,135)	(7,524)
Available for sale securities, fair value	271,611	274,594
Securities Held to Maturity:
Held to maturity securities, amortized cost	28	30
Held to maturity securities, fair value	28	30
US Government Agencies Debt Securities [Member]
U.S. Government Agencies
Available for sale securities, amortized cost	271,010	278,419
Available for sale securities, gross unrealized gains	485	156
Available for sale securities, gross unrealized losses	(4,115)	(7,511)
Available for sale securities, fair value	267,380	271,064
US States and Political Subdivisions Debt Securities [Member]
U.S. Government Agencies
Available for sale securities, amortized cost	4,207	3,516
Available for sale securities, gross unrealized gains	44	27
Available for sale securities, gross unrealized losses	(20)	(13)
Available for sale securities, fair value	4,231	3,530
Securities Held to Maturity:
Held to maturity securities, amortized cost	28	30
Held to maturity securities, gross unrealized gains	0	0
Held to maturity securities, gross unrealized losses	0	0
Held to maturity securities, fair value	$ 28	$ 30

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

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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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Amount after other than temporary impairment (OTTI) accretion, of investments in debt securities classified as held-to-maturity.

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Amount of accumulated unrealized gain on investments in debt securities classified as held-to-maturity.

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Fair value of investments in debt securities classified as held-to-maturity.

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