Note 4 - Securities (Details) - Available-for-sale Securities - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Note 4 - Securities (Details) - Available-for-sale Securities [Line Items]
Amortized cost	$ 564,391	$ 509,276
Unrealized gains	3,954	5,829
Unrealized losses	2,469	2,049
Fair value	565,876	513,056
US Treasury Securities [Member]
Note 4 - Securities (Details) - Available-for-sale Securities [Line Items]
Amortized cost	79,999	70,000
Unrealized gains	1
Fair value	80,000	70,000
US Government-sponsored Enterprises Debt Securities [Member]
Note 4 - Securities (Details) - Available-for-sale Securities [Line Items]
Amortized cost	251,190	203,531
Unrealized gains	1,468	2,017
Unrealized losses	765	562
Fair value	251,893	204,986
Mortgage-backed Securities, Issued by US Government Sponsored Enterprises [Member]
Note 4 - Securities (Details) - Available-for-sale Securities [Line Items]
Amortized cost	170,139	173,573
Unrealized gains	1,143	2,042
Unrealized losses	1,654	1,345
Fair value	169,628	174,270
US States and Political Subdivisions Debt Securities [Member]
Note 4 - Securities (Details) - Available-for-sale Securities [Line Items]
Amortized cost	62,410	61,416
Unrealized gains	1,342	1,560
Unrealized losses	50	142
Fair value	63,702	62,834
Common Stock [Member]
Note 4 - Securities (Details) - Available-for-sale Securities [Line Items]
Amortized cost	653	756
Unrealized gains		210
Fair value	$ 653	$ 966

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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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