Note 9 - Revenue Recognition - Noninterest Income (Details) - USD ($) $ in Thousands	3 Months Ended
Mar. 31, 2018	Mar. 31, 2017
Noninterest Income (in-scope of Topic 606)	$ 1,540	$ 1,459
Noninterest Income (out-of-scope of Topic 606)	483	391
Total noninterest income	2,023	1,850
Deposit Account [Member]
Noninterest Income (in-scope of Topic 606)	670	665
Product and Service, Other [Member]
Noninterest Income (in-scope of Topic 606)	33	69
Credit and Debit Card [Member]
Noninterest Income (in-scope of Topic 606)	344	244
Fiduciary and Trust [Member]
Noninterest Income (in-scope of Topic 606)	402	401
Insurance and Investment [Member]
Noninterest Income (in-scope of Topic 606)	$ 91	$ 80

Amount, including tax collected from customer, of revenue from satisfaction of performance obligation by transferring promised good or service to customer. Tax collected from customer is tax assessed by governmental authority that is both imposed on and concurrent with specific revenue-producing transaction, including, but not limited to, sales, use, value-added and excise.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 1
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=109196051&loc=SL49130539-203045

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 5
-URI http://asc.fasb.org/extlink&oid=109196051&loc=SL49130545-203045

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 4
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=109196051&loc=SL49130543-203045

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Period Type:	duration