Note 4 - Loans Receivable and Allowance for Loan and Lease Losses - Impaired Loans (Details) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018	Dec. 31, 2018
Impaired loans, related allowance	$ 0		$ 0		$ 1,500,000
Impaired loans, recorded investment	21,000,000		21,000,000		21,200,000
With no allowance recorded, average recorded investment	22,105,000	$ 8,460,000	19,224,000	$ 7,828,000
With no allowance recorded, interest income recognized	212,000	36,000	545,000	70,000
With allowance recorded, average recorded investment	4,216,000	296,000	5,376,000	246,000
With allowance recorded, interest income recognized
Impaired Loans, Average recorded investment	26,321,000	8,756,000	24,600,000	8,074,000
Impaired Loans, interest income recognized	212,000	36,000	545,000	70,000
Business Activities Loans [Member]
Impaired loans with no related allowance recorded, recorded investment	20,993,000		20,993,000		15,391,000
Impaired loans with no related allowance recorded, unpaid principal balance	21,160,000		21,160,000		16,799,000
Impaired loans with a related allowance recorded, recorded investment					5,827,000
Impaired loans with a related allowance recorded, unpaid principal balance					5,877,000
Impaired loans, related allowance					1,545,000
Impaired loans, recorded investment	20,993,000		20,993,000		21,218,000
Impaired loans, unpaid principal balance	21,160,000		21,160,000		22,676,000
Commercial Real Estate Portfolio Segment [Member]
With no allowance recorded, average recorded investment	10,490,000	3,250,000	7,956,000	2,770,000
With no allowance recorded, interest income recognized	120,000	25,000	186,000	49,000
With allowance recorded, average recorded investment	215,000		393,000
With allowance recorded, interest income recognized
Impaired Loans, Average recorded investment	10,705,000	3,250,000	8,349,000	2,770,000
Impaired Loans, interest income recognized	120,000	25,000	186,000	49,000
Commercial Real Estate Portfolio Segment [Member] | Business Activities Loans [Member]
Impaired loans with no related allowance recorded, recorded investment	13,466,000		13,466,000		4,606,000
Impaired loans with no related allowance recorded, unpaid principal balance	13,529,000		13,529,000		5,109,000
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	13,466,000		13,466,000		4,606,000
Impaired loans, unpaid principal balance	13,529,000		13,529,000		5,109,000
Residential Portfolio Segment [Member]
With no allowance recorded, average recorded investment	2,271,000	3,480,000	1,584,000	3,421,000
With no allowance recorded, interest income recognized	41,000	3,000	98,000	6,000
With allowance recorded, average recorded investment	1,505,000		1,767,000
With allowance recorded, interest income recognized
Impaired Loans, Average recorded investment	3,776,000	3,480,000	3,351,000	3,421,000
Impaired Loans, interest income recognized	41,000	3,000	98,000	6,000
Residential Portfolio Segment [Member] | Business Activities Loans [Member]
Impaired loans with no related allowance recorded, recorded investment	3,851,000		3,851,000		670,000
Impaired loans with no related allowance recorded, unpaid principal balance	3,902,000		3,902,000		703,000
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	3,851,000		3,851,000		2,302,000
Impaired loans, unpaid principal balance	3,902,000		3,902,000		2,335,000
Commercial Portfolio Segment [Member]
With no allowance recorded, average recorded investment	1,854,000	980,000	1,275,000	912,000
With no allowance recorded, interest income recognized	38,000		87,000
With allowance recorded, average recorded investment	2,459,000	293,000	3,183,000	244,000
With allowance recorded, interest income recognized
Impaired Loans, Average recorded investment	4,313,000	1,273,000	4,458,000	1,156,000
Impaired Loans, interest income recognized	38,000		87,000
Commercial Portfolio Segment [Member] | Business Activities Loans [Member]
Impaired loans with no related allowance recorded, recorded investment	2,676,000		2,676,000		488,000
Impaired loans with no related allowance recorded, unpaid principal balance	2,726,000		2,726,000		1,281,000
Impaired loans with a related allowance recorded, recorded investment					4,158,000
Impaired loans with a related allowance recorded, unpaid principal balance					4,208,000
Impaired loans, related allowance					1,299,000
Impaired loans, recorded investment	2,676,000		2,676,000		4,646,000
Impaired loans, unpaid principal balance	2,726,000		2,726,000		5,489,000
Consumer Portfolio Segment [Member]
With no allowance recorded, average recorded investment	890,000	750,000	866,000	725,000
With no allowance recorded, interest income recognized	13,000	8,000	24,000	15,000
With allowance recorded, average recorded investment	37,000	3,000	33,000	2,000
With allowance recorded, interest income recognized
Impaired Loans, Average recorded investment	927,000	753,000	899,000	727,000
Impaired Loans, interest income recognized	13,000	8,000	24,000	15,000
Consumer Portfolio Segment [Member] | Business Activities Loans [Member]
Impaired loans with no related allowance recorded, recorded investment	1,000,000		1,000,000		827,000
Impaired loans with no related allowance recorded, unpaid principal balance	1,003,000		1,003,000		867,000
Impaired loans with a related allowance recorded, recorded investment					37,000
Impaired loans with a related allowance recorded, unpaid principal balance					37,000
Impaired loans, related allowance					30,000
Impaired loans, recorded investment	1,000,000		1,000,000		864,000
Impaired loans, unpaid principal balance	1,003,000		1,003,000		904,000
Construction Portfolio Segment [Member]
With no allowance recorded, average recorded investment	6,600,000		7,543,000
With no allowance recorded, interest income recognized			150,000
With allowance recorded, average recorded investment	6,600,000		7,543,000
With allowance recorded, interest income recognized			150,000
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					8,800,000
Impaired loans with a related allowance recorded, unpaid principal balance					8,839,000
Impaired loans, related allowance