Note 8 - Loans and Related Allowance for Loan and Lease Losses - Troubled Debt Restructurings (Details) $ in Thousands	3 Months Ended
Mar. 31, 2018 USD ($)
Commercial And Industrial [Member]
Number of contracts	2
Pre-modification outstanding recorded investment	$ 6,977
Post-modification outstanding recorded investment	$ 6,977
Real Estate Mortgage Portfolio Segment [Member] \| Residential Loan [Member]
Number of contracts	2
Pre-modification outstanding recorded investment	$ 63
Post-modification outstanding recorded investment	$ 63
Extended Maturity [Member] \| Commercial And Industrial [Member]
Number of contracts	2
Extended Maturity [Member] \| Real Estate Mortgage Portfolio Segment [Member] \| Residential Loan [Member]
Number of contracts	2
Other Restructurings [Member] \| Commercial And Industrial [Member]
Number of contracts
Other Restructurings [Member] \| Real Estate Mortgage Portfolio Segment [Member] \| Residential Loan [Member]
Number of contracts

Number of financing receivables that have been modified by troubled debt restructurings.

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 33
-URI http://asc.fasb.org/extlink&oid=118936363&loc=SL6953676-111524

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Amount, after troubled debt restructuring, of modified financing receivable.

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Amount, before troubled debt restructuring, of financing receivable to be modified.

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