Note 11 - Securities Sold Under Agreement to Repurchase (Details Textual) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Federal Funds Purchased and Securities Sold under Agreements to Repurchase	$ 13,400	$ 19,100
Line of Credit Facility, Maximum Borrowing Capacity	14,750	$ 14,750
Overnight Borrowings [Member]
Line of Credit Facility, Maximum Borrowing Capacity	$ 103,000

Amount after offset of short term borrowing where a bank borrows, at the federal funds rate, from another bank and securities that an entity sells and agrees to repurchase at a specified date for a specified price.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03.13(1))
-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

Name:	us-gaap_FederalFundsPurchasedAndSecuritiesSoldUnderAgreementsToRepurchase
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant