Note 17 - Off-balance Sheet Arrangements and Commitments (Details Textual) $ in Millions	12 Months Ended
Dec. 31, 2017 USD ($)
Percent of Limit	2.40%
Derivative [Member]
Loans and Leases Receivable, Commitments to Purchase or Sell	$ 1
Minimum [Member]
Funding Period	180 days
Maximum [Member]
Funding Period	2 years

Reflects the carrying amount of loans and leases for which agreements to acquire or dispose exist.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 825
-Section 50
-Paragraph 1
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=75032840&loc=d3e61044-112788

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 825
-Section 50
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=75032840&loc=d3e61082-112788

Name:	us-gaap_LoansAndLeasesReceivableCommitmentsToPurchaseOrSell
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration