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Note 8 - Loans and Related Allowance for Loan and Lease Losses - Troubled Debt Restructurings (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2018 USD ($)	Mar. 31, 2017 USD ($)
Commercial And Industrial [Member]
Number of contracts	2	1
Pre-modification outstanding recorded investment	$ 6,977	$ 50
Post-modification outstanding recorded investment	$ 6,977	$ 50
Real Estate Mortgage Portfolio Segment [Member] | Residential Loan [Member]
Number of contracts	2	2
Pre-modification outstanding recorded investment	$ 63	$ 36
Post-modification outstanding recorded investment	$ 63	$ 36
Extended Maturity [Member] | Commercial And Industrial [Member]
Number of contracts	2	1
Extended Maturity [Member] | Real Estate Mortgage Portfolio Segment [Member] | Residential Loan [Member]
Number of contracts	2	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

X

- Definition

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

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 33
-URI http://asc.fasb.org/extlink&oid=84173941&loc=SL6953676-111524

+ Details

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Namespace Prefix:	us-gaap_
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Balance Type:	na
Period Type:	duration

X

- Definition

Post-modification amount of investment in financing receivables modified by troubled debt restructurings.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 33
-URI http://asc.fasb.org/extlink&oid=84173941&loc=SL6953676-111524

+ Details

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Namespace Prefix:	us-gaap_
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X

- Definition

Pre-modification amount of investment in financing receivables modified by troubled debt restructurings.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 33
-URI http://asc.fasb.org/extlink&oid=84173941&loc=SL6953676-111524

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X

- Details

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- Details

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