Note 5 - Loans Receivable and Allowance for Loan and Lease Losses - Impaired Loans (Details) - USD ($)	12 Months Ended
Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Impaired loans, related allowance	$ 1,500,000	$ 253,000
Impaired loans, recorded investment	21,200,000	6,800,000
With no allowance recorded, average recorded investment	9,563,000	8,638,000	$ 12,056,000
With no allowance recorded, interest income recognized	645,000	135,000	340,000
With allowance recorded, average recorded investment	609,000	243,000	2,205,000
With allowance recorded, interest income recognized
Impaired Loans, Average recorded investment	10,172,000	8,881,000	14,261,000
Impaired Loans, interest income recognized	645,000	135,000	340,000
Business Activities Loans [Member]
Impaired loans with no related allowance recorded, recorded investment	15,391,000	6,500,000
Impaired loans with no related allowance recorded, unpaid principal balance	16,799,000	7,295,000
Impaired loans with a related allowance recorded, recorded investment	5,827,000	253,000
Impaired loans with a related allowance recorded, unpaid principal balance	5,877,000	253,000
Impaired loans, related allowance	1,545,000	253,000
Impaired loans, recorded investment	21,218,000	6,753,000
Impaired loans, unpaid principal balance	22,676,000	7,548,000
Commercial Real Estate Portfolio Segment [Member]
With no allowance recorded, average recorded investment	3,318,000	5,832,000	6,929,000
With no allowance recorded, interest income recognized	100,000	102,000	312,000
With allowance recorded, average recorded investment			65,000
With allowance recorded, interest income recognized
Impaired Loans, Average recorded investment	3,318,000	5,832,000	6,994,000
Impaired Loans, interest income recognized	100,000	102,000	312,000
Commercial Real Estate Portfolio Segment [Member] \| Business Activities Loans [Member]
Impaired loans with no related allowance recorded, recorded investment	4,606,000	1,977,000
Impaired loans with no related allowance recorded, unpaid principal balance	5,109,000	2,425,000
Impaired loans with a related allowance recorded, recorded investment
Impaired loans with a related allowance recorded, unpaid principal balance
Impaired loans, related allowance
Impaired loans, recorded investment	4,606,000	1,977,000
Impaired loans, unpaid principal balance	5,109,000	2,425,000
Residential Portfolio Segment [Member]
With no allowance recorded, average recorded investment	3,154,000	2,016,000	4,318,000
With no allowance recorded, interest income recognized	11,000	11,000	9,000
With allowance recorded, average recorded investment	126,000
With allowance recorded, interest income recognized
Impaired Loans, Average recorded investment	3,280,000	2,016,000	4,318,000
Impaired Loans, interest income recognized	11,000	11,000	9,000
Residential Portfolio Segment [Member] \| Business Activities Loans [Member]
Impaired loans with no related allowance recorded, recorded investment	670,000	3,336,000
Impaired loans with no related allowance recorded, unpaid principal balance	703,000	3,369,000
Impaired loans with a related allowance recorded, recorded investment	1,632,000
Impaired loans with a related allowance recorded, unpaid principal balance	1,632,000
Impaired loans, related allowance	216,000
Impaired loans, recorded investment	2,302,000	3,336,000
Impaired loans, unpaid principal balance	2,335,000	3,369,000
Commercial Portfolio Segment [Member]
With no allowance recorded, average recorded investment	987,000	197,000	265,000
With no allowance recorded, interest income recognized
With allowance recorded, average recorded investment	474,000	243,000	2,138,000
With allowance recorded, interest income recognized
Impaired Loans, Average recorded investment	1,461,000	440,000	2,403,000
Impaired Loans, interest income recognized
Commercial Portfolio Segment [Member] \| Business Activities Loans [Member]
Impaired loans with no related allowance recorded, recorded investment	488,000	497,000
Impaired loans with no related allowance recorded, unpaid principal balance	1,281,000	683,000
Impaired loans with a related allowance recorded, recorded investment	4,158,000	251,000
Impaired loans with a related allowance recorded, unpaid principal balance	4,208,000	251,000
Impaired loans, related allowance	1,299,000	251,000
Impaired loans, recorded investment	4,646,000	748,000
Impaired loans, unpaid principal balance	5,489,000	934,000
Consumer Portfolio Segment [Member]
With no allowance recorded, average recorded investment	750,000	593,000	544,000
With no allowance recorded, interest income recognized	31,000	22,000	19,000
With allowance recorded, average recorded investment	9,000		2,000
With allowance recorded, interest income recognized
Impaired Loans, Average recorded investment	759,000	593,000	546,000
Impaired Loans, interest income recognized	31,000	22,000	19,000
Consumer Portfolio Segment [Member] \| Business Activities Loans [Member]
Impaired loans with no related allowance recorded, recorded investment	827,000	690,000
Impaired loans with no related allowance recorded, unpaid principal balance	867,000	818,000
Impaired loans with a related allowance recorded, recorded investment	37,000	2,000
Impaired loans with a related allowance recorded, unpaid principal balance	37,000	2,000
Impaired loans, related allowance	30,000	2,000
Impaired loans, recorded investment	864,000	692,000
Impaired loans, unpaid principal balance	904,000	820,000
Construction Portfolio Segment [Member]
With no allowance recorded, average recorded investment	1,354,000
With no allowance recorded, interest income recognized	503,000
With allowance recorded, average recorded investment
With allowance recorded, interest income recognized
Impaired Loans, Average recorded investment	1,354,000
Impaired Loans, interest income recognized	503,000
Construction Portfolio Segment [Member] \| Business Activities Loans [Member]
Impaired loans with no related allowance recorded, recorded investment	8,800,000
Impaired loans with no related allowance recorded, unpaid principal balance	8,839,000
Impaired loans with a related allowance recorded, recorded investment
Impaired loans with a related allowance recorded, unpaid principal balance
Impaired loans, related allowance
Impaired loans, recorded investment	8,800,000
Impaired loans, unpaid principal balance	$ 8,839,000

Average amount of investment of impaired financing receivables with related allowance for credit losses and without a related allowance for credit losses.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 15
-Subparagraph (c)(1)
-URI http://asc.fasb.org/extlink&oid=84173941&loc=d3e5212-111524

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 17
-URI http://asc.fasb.org/extlink&oid=84173941&loc=d3e5258-111524

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