Note 18 - Assets and Liabilities Measured and Reported at Fair Value - Assets Measured at Fair Value on a Recurring Basis (Details) - USD ($)	Mar. 31, 2017	Dec. 31, 2016
Fair value	$ 556,144,000	$ 570,074,000
Fair Value, Measurements, Recurring [Member]
Fair value	556,144,000	570,074,000
Interest rate swaps	438,000	203,000
Total assets	556,582,000	570,277,000
Interest rate swaps	331,000	178,000
Fair Value, Measurements, Recurring [Member] \| Fair Value, Inputs, Level 1 [Member]
Fair value	776,000	75,697,000
Interest rate swaps
Total assets	776,000	75,697,000
Interest rate swaps
Fair Value, Measurements, Recurring [Member] \| Fair Value, Inputs, Level 2 [Member]
Fair value	555,368,000	494,377,000
Interest rate swaps	438,000	203,000
Total assets	555,806,000	494,580,000
Interest rate swaps	331,000	178,000
Fair Value, Measurements, Recurring [Member] \| Fair Value, Inputs, Level 3 [Member]
Fair value
Interest rate swaps
Total assets	0	0
Interest rate swaps
US Government-sponsored Enterprises Debt Securities [Member]
Fair value	339,946,000	268,090,000
US Government-sponsored Enterprises Debt Securities [Member] \| Fair Value, Measurements, Recurring [Member]
Fair value	339,946,000	268,090,000
US Government-sponsored Enterprises Debt Securities [Member] \| Fair Value, Measurements, Recurring [Member] \| Fair Value, Inputs, Level 1 [Member]
Fair value
US Government-sponsored Enterprises Debt Securities [Member] \| Fair Value, Measurements, Recurring [Member] \| Fair Value, Inputs, Level 2 [Member]
Fair value	339,946,000	268,090,000
US Government-sponsored Enterprises Debt Securities [Member] \| Fair Value, Measurements, Recurring [Member] \| Fair Value, Inputs, Level 3 [Member]
Fair value
US Treasury and Government [Member] \| Fair Value, Measurements, Recurring [Member]
Fair value		74,998,000
US Treasury and Government [Member] \| Fair Value, Measurements, Recurring [Member] \| Fair Value, Inputs, Level 1 [Member]
Fair value		74,998,000
US Treasury and Government [Member] \| Fair Value, Measurements, Recurring [Member] \| Fair Value, Inputs, Level 2 [Member]
Fair value
US Treasury and Government [Member] \| Fair Value, Measurements, Recurring [Member] \| Fair Value, Inputs, Level 3 [Member]
Fair value
Mortgage-backed Securities, Issued by US Government Sponsored Enterprises [Member]
Fair value	160,558,000	168,843,000
Mortgage-backed Securities, Issued by US Government Sponsored Enterprises [Member] \| Fair Value, Measurements, Recurring [Member]
Fair value	160,558,000	168,843,000
Mortgage-backed Securities, Issued by US Government Sponsored Enterprises [Member] \| Fair Value, Measurements, Recurring [Member] \| Fair Value, Inputs, Level 1 [Member]
Fair value
Mortgage-backed Securities, Issued by US Government Sponsored Enterprises [Member] \| Fair Value, Measurements, Recurring [Member] \| Fair Value, Inputs, Level 2 [Member]
Fair value	160,558,000	168,843,000
Mortgage-backed Securities, Issued by US Government Sponsored Enterprises [Member] \| Fair Value, Measurements, Recurring [Member] \| Fair Value, Inputs, Level 3 [Member]
Fair value
US States and Political Subdivisions Debt Securities [Member]
Fair value	54,864,000	57,444,000
US States and Political Subdivisions Debt Securities [Member] \| Fair Value, Measurements, Recurring [Member]
Fair value	54,864,000	57,444,000
US States and Political Subdivisions Debt Securities [Member] \| Fair Value, Measurements, Recurring [Member] \| Fair Value, Inputs, Level 1 [Member]
Fair value
US States and Political Subdivisions Debt Securities [Member] \| Fair Value, Measurements, Recurring [Member] \| Fair Value, Inputs, Level 2 [Member]
Fair value	54,864,000	57,444,000
US States and Political Subdivisions Debt Securities [Member] \| Fair Value, Measurements, Recurring [Member] \| Fair Value, Inputs, Level 3 [Member]
Fair value
Common Stock [Member]
Fair value	776,000	699,000
Common Stock [Member] \| Fair Value, Measurements, Recurring [Member]
Fair value	776,000	699,000
Common Stock [Member] \| Fair Value, Measurements, Recurring [Member] \| Fair Value, Inputs, Level 1 [Member]
Fair value	776,000	699,000
Common Stock [Member] \| Fair Value, Measurements, Recurring [Member] \| Fair Value, Inputs, Level 2 [Member]
Fair value
Common Stock [Member] \| Fair Value, Measurements, Recurring [Member] \| Fair Value, Inputs, Level 3 [Member]
Fair value

Fair value portion of probable future economic benefits obtained or controlled by an entity as a result of past transactions or events.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=66048111&loc=d3e19207-110258

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

+ References

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=75030427&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=82897076&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=82896770&loc=d3e26610-111562

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Fair value as of the balance sheet date of interest rate derivative assets, which includes all such derivative instruments in hedging and nonhedging relationships that are recognized as assets.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 825
-SubTopic 10
-Section 50
-Paragraph 10
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=77997519&loc=d3e13433-108611

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Fair value as of the balance sheet date of interest rate derivative liabilities, which includes all such derivative instruments in hedging and nonhedging relationships that are recognized as liabilities.

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