Note 3 - Loans and Allowance for Loan Losses - Impaired Loans (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017
Originated Loan [Member]
With no related allowance recorded, unpaid principal balance	$ 4,139,000		$ 4,139,000		$ 4,915,000
With no related allowance recorded, principal balance	3,039,000		3,039,000		3,150,000
With no related allowance recorded, average recorded principal balance	2,459,000	$ 1,992,000	3,171,000	$ 2,439,000
With related allowance recorded, unpaid principal balance	9,004,000		9,004,000		5,837,000
With related allowance recorded, principal balance	8,906,000		8,906,000		5,637,000
Related allowance	998,000		998,000		1,867,000
With related allowance recorded, average recorded principal balance	6,841,000	8,654,000	6,031,000	9,783,000
Total unpaid principal balance	13,143,000		13,143,000		10,752,000
Total principal balance	11,945,000		11,945,000		8,787,000
Total average recorded principal balance	9,300,000	10,646,000	9,202,000	12,222,000
Originated Loan [Member] | Commercial Portfolio Segment [Member]
With no related allowance recorded, unpaid principal balance	2,195,000		2,195,000		3,096,000
With no related allowance recorded, principal balance	1,804,000		1,804,000		2,014,000
With no related allowance recorded, average recorded principal balance	1,338,000	649,000	2,034,000	1,319,000
With related allowance recorded, unpaid principal balance	8,147,000		8,147,000		4,447,000
With related allowance recorded, principal balance	8,125,000		8,125,000		4,380,000
Related allowance	750,000		750,000		1,202,000
With related allowance recorded, average recorded principal balance	6,032,000	7,506,000	5,099,000	8,792,000
Total unpaid principal balance	10,342,000		10,342,000		7,543,000
Total principal balance	9,929,000		9,929,000		6,394,000
Total average recorded principal balance	7,370,000	8,155,000	7,133,000	10,111,000
Originated Loan [Member] | Commercial Portfolio Segment [Member] | Commercial and Industrial [Member]
With no related allowance recorded, unpaid principal balance	1,294,000		1,294,000		765,000
With no related allowance recorded, principal balance	951,000		951,000		178,000
With no related allowance recorded, average recorded principal balance	732,000	56,000	469,000	823,000
With related allowance recorded, unpaid principal balance	5,102,000		5,102,000		3,038,000
With related allowance recorded, principal balance	5,099,000		5,099,000		2,989,000
Related allowance	348,000		348,000		963,000
With related allowance recorded, average recorded principal balance	3,572,000	4,100,000	3,067,000	3,395,000
Originated Loan [Member] | Commercial Portfolio Segment [Member] | Vacant Land and Land Development and Residential Construction Loan [Member]
With no related allowance recorded, unpaid principal balance	96,000		96,000		454,000
With no related allowance recorded, principal balance	96,000		96,000		35,000
With no related allowance recorded, average recorded principal balance	98,000	58,000	58,000	73,000
With related allowance recorded, unpaid principal balance	0		0		0
With related allowance recorded, principal balance	0		0		0
Related allowance	0		0		0
With related allowance recorded, average recorded principal balance	0	374,000	0	561,000
Originated Loan [Member] | Commercial Portfolio Segment [Member] | Real Estate Owner Occupied Loan [Member]
With no related allowance recorded, unpaid principal balance	783,000		783,000		1,528,000
With no related allowance recorded, principal balance	735,000		735,000		1,452,000
With no related allowance recorded, average recorded principal balance	383,000	266,000	1,273,000	189,000
With related allowance recorded, unpaid principal balance	2,903,000		2,903,000		1,409,000
With related allowance recorded, principal balance	2,887,000		2,887,000		1,391,000
Related allowance	386,000		386,000		239,000
With related allowance recorded, average recorded principal balance	2,320,000	2,319,000	1,926,000	1,731,000
Originated Loan [Member] | Commercial Portfolio Segment [Member] | Real Estate Non Owner Occupied Loan [Member]
With no related allowance recorded, unpaid principal balance	0		0		0
With no related allowance recorded, principal balance	0		0		0
With no related allowance recorded, average recorded principal balance	0	89,000	0	45,000
With related allowance recorded, unpaid principal balance	0		0		0
With related allowance recorded, principal balance	0		0		0
Related allowance	0		0		0
With related allowance recorded, average recorded principal balance	0	392,000	0	2,569,000
Originated Loan [Member] | Commercial Portfolio Segment [Member] | Real Estate Multi Family and Residential Rental Loan [Member]
With no related allowance recorded, unpaid principal balance	22,000		22,000		349,000
With no related allowance recorded, principal balance	22,000		22,000		349,000
With no related allowance recorded, average recorded principal balance	125,000	180,000	234,000	189,000
With related allowance recorded, unpaid principal balance	142,000		142,000		0
With related allowance recorded, principal balance	139,000		139,000		0
Related allowance	16,000		16,000		0
With related allowance recorded, average recorded principal balance	140,000	321,000	106,000	536,000
Originated Loan [Member] | Retail Portfolio Segment [Member]
With no related allowance recorded, unpaid principal balance	1,944,000		1,944,000		1,819,000
With no related allowance recorded, principal balance	1,235,000		1,235,000		1,136,000
With no related allowance recorded, average recorded principal balance	1,121,000	1,343,000	1,137,000	1,120,000
With related allowance recorded, unpaid principal balance	857,000		857,000		1,390,000
With related allowance recorded, principal balance	781,000		781,000		1,257,000
Related allowance	248,000		248,000		665,000
With related allowance recorded, average recorded principal balance	809,000	1,148,000	932,000	991,000
Total unpaid principal balance	2,801,000		2,801,000		3,209,000
Total principal balance	2,016,000		2,016,000		2,393,000
Total average recorded principal balance	1,930,000	2,491,000	2,069,000	2,111,000
Originated Loan [Member] | Retail Portfolio Segment [Member] | Home Equity and Other [Member]
With no related allowance recorded, unpaid principal balance	853,000		853,000		693,000
With no related allowance recorded, principal balance	821,000		821,000		680,000
With no related allowance recorded, average recorded principal balance	719,000	729,000	717,000	488,000
With related allowance recorded, unpaid principal balance	447,000		447,000		1,225,000
With related allowance recorded, principal balance	436,000		436,000		1,147,000
Related allowance	199,000		199,000		652,000
With related allowance recorded, average recorded principal balance	463,000	1,035,000	643,000	866,000
Originated Loan [Member] | Retail Portfolio Segment [Member] | One to Four Family Mortgages [Member]
With no related allowance recorded, unpaid principal balance	1,091,000		1,091,000		1,126,000
With no related allowance recorded, principal balance	414,000		414,000		456,000
With no related allowance recorded, average recorded principal balance	402,000	614,000	420,000	632,000
With related allowance recorded, unpaid principal balance	410,000		410,000		165,000
With related allowance recorded, principal balance	345,000		345,000		110,000
Related allowance	49,000		49,000		13,000
With related allowance recorded, average recorded principal balance	346,000	113,000	289,000	125,000
Acquired Loan [Member]
With no related allowance recorded, unpaid principal balance	4,919,000		4,919,000		5,938,000
With no related allowance recorded, principal balance	4,318,000		4,318,000		4,795,000
With no related allowance recorded, average recorded principal balance	4,346,000	6,410,000	4,469,000	5,680,000
With related allowance recorded, unpaid principal balance	0		0		0
With related allowance recorded, principal balance	0		0		0
Related allowance	0		0		0
With related allowance recorded, average recorded principal balance	34,000	223,000	412,000	230,000
Total unpaid principal balance	4,919,000		4,919,000		5,938,000
Total principal balance	4,318,000		4,318,000		4,795,000
Total average recorded principal balance	4,380,000	6,633,000	4,881,000	5,910,000
Acquired Loan [Member] | Commercial Portfolio Segment [Member]
With no related allowance recorded, unpaid principal balance	1,408,000		1,408,000		2,541,000
With no related allowance recorded, principal balance	1,380,000		1,380,000		2,135,000
With no related allowance recorded, average recorded principal balance	1,495,000	3,983,000	1,714,000	3,468,000
With related allowance recorded, unpaid principal balance	0		0		0
With related allowance recorded, principal balance	0		0		0
Related allowance	0		0		0
With related allowance recorded, average recorded principal balance	0	53,000	400,000	59,000
Total unpaid principal balance	1,408,000		1,408,000		2,541,000
Total principal balance	1,380,000		1,380,000		2,135,000
Total average recorded principal balance	1,495,000	4,036,000	2,114,000	3,527,000
Acquired Loan [Member] | Commercial Portfolio Segment [Member] | Commercial and Industrial [Member]
With no related allowance recorded, unpaid principal balance	598,000		598,000		1,039,000
With no related allowance recorded, principal balance	589,000		589,000		1,021,000
With no related allowance recorded, average recorded principal balance	648,000	1,196,000	763,000	1,044,000
With related allowance recorded, unpaid principal balance	0		0		0
With related allowance recorded, principal balance	0		0		0
Related allowance	0		0		0
With related allowance recorded, average recorded principal balance	0	6,000	0	12,000
Acquired Loan [Member] | Commercial Portfolio Segment [Member] | Vacant Land and Land Development and Residential Construction Loan [Member]
With no related allowance recorded, unpaid principal balance	0		0		0
With no related allowance recorded, principal balance	0		0		0
With no related allowance recorded, average recorded principal balance	0	31,000	0	15,000
With related allowance recorded, unpaid principal balance	0		0		0
With related allowance recorded, principal balance	0		0		0
Related allowance	0		0		0
With related allowance recorded, average recorded principal balance	0	0	0	0
Acquired Loan [Member] | Commercial Portfolio Segment [Member] | Real Estate Owner Occupied Loan [Member]
With no related allowance recorded, unpaid principal balance	538,000		538,000		1,027,000
With no related allowance recorded, principal balance	538,000		538,000		659,000
With no related allowance recorded, average recorded principal balance	588,000	1,031,000	638,000	1,091,000
With related allowance recorded, unpaid principal balance	0		0		0
With related allowance recorded, principal balance	0		0		0
Related allowance	0		0		0
With related allowance recorded, average recorded principal balance	0	47,000	400,000	47,000
Acquired Loan [Member] | Commercial Portfolio Segment [Member] | Real Estate Non Owner Occupied Loan [Member]
With no related allowance recorded, unpaid principal balance	217,000		217,000		238,000
With no related allowance recorded, principal balance	217,000		217,000		237,000
With no related allowance recorded, average recorded principal balance	221,000	975,000	228,000	863,000
With related allowance recorded, unpaid principal balance	0		0		0
With related allowance recorded, principal balance	0		0		0
Related allowance	0		0		0
With related allowance recorded, average recorded principal balance	0	0	0	0
Acquired Loan [Member] | Commercial Portfolio Segment [Member] | Real Estate Multi Family and Residential Rental Loan [Member]
With no related allowance recorded, unpaid principal balance	55,000		55,000		237,000
With no related allowance recorded, principal balance	36,000		36,000		218,000
With no related allowance recorded, average recorded principal balance	38,000	750,000	85,000	455,000
With related allowance recorded, unpaid principal balance	0		0		0
With related allowance recorded, principal balance	0		0		0
Related allowance	0		0		0
With related allowance recorded, average recorded principal balance	0	0	0	0
Acquired Loan [Member] | Retail Portfolio Segment [Member]
With no related allowance recorded, unpaid principal balance	3,511,000		3,511,000		3,397,000
With no related allowance recorded, principal balance	2,938,000		2,938,000		2,660,000
With no related allowance recorded, average recorded principal balance	2,851,000	2,427,000	2,755,000	2,212,000
With related allowance recorded, unpaid principal balance	0		0		0
With related allowance recorded, principal balance	0		0		0
Related allowance	0		0		0
With related allowance recorded, average recorded principal balance	34,000	170,000	12,000	171,000
Total unpaid principal balance	3,511,000		3,511,000		3,397,000
Total principal balance	2,938,000		2,938,000		2,660,000
Total average recorded principal balance	2,885,000	2,597,000	2,767,000	2,383,000
Acquired Loan [Member] | Retail Portfolio Segment [Member] | Home Equity and Other [Member]
With no related allowance recorded, unpaid principal balance	830,000		830,000		694,000
With no related allowance recorded, principal balance	785,000		785,000		507,000
With no related allowance recorded, average recorded principal balance	778,000	453,000	678,000	394,000
With related allowance recorded, unpaid principal balance	0		0		0
With related allowance recorded, principal balance	0		0		0
Related allowance	0		0		0
With related allowance recorded, average recorded principal balance	34,000	0	12,000	0
Acquired Loan [Member] | Retail Portfolio Segment [Member] | One to Four Family Mortgages [Member]
With no related allowance recorded, unpaid principal balance	2,681,000		2,681,000		2,703,000
With no related allowance recorded, principal balance	2,153,000		2,153,000		2,153,000
With no related allowance recorded, average recorded principal balance	2,073,000	1,974,000	2,077,000	1,818,000
With related allowance recorded, unpaid principal balance	0		0		0
With related allowance recorded, principal balance	0		0		0
Related allowance	0		0		$ 0
With related allowance recorded, average recorded principal balance	$ 0	$ 170,000	$ 0	$ 171,000