Note 3 - Loans and Allowance for Loan Losses - Impaired Loans (Details) - USD ($)	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Dec. 31, 2018
Originated Loan [Member]
With no related allowance recorded, unpaid principal balance	$ 11,832,000		$ 10,990,000
With no related allowance recorded, principal balance	11,141,000		10,306,000
With no related allowance recorded, average recorded principal balance	10,724,000	$ 3,883,000
With related allowance recorded, unpaid principal balance	9,144,000		8,660,000
With related allowance recorded, principal balance	9,050,000		8,576,000
Related allowance	1,046,000		689,000
With related allowance recorded, average recorded principal balance	8,812,000	5,220,000
Total unpaid principal balance	20,976,000		19,650,000
Total principal balance	20,191,000		18,882,000
Total average recorded principal balance	19,536,000	9,103,000
Originated Loan [Member] | Commercial Portfolio Segment [Member]
With no related allowance recorded, unpaid principal balance	10,171,000		9,330,000
With no related allowance recorded, principal balance	10,170,000		9,330,000
With no related allowance recorded, average recorded principal balance	9,750,000	2,730,000
With related allowance recorded, unpaid principal balance	8,343,000		7,809,000
With related allowance recorded, principal balance	8,333,000		7,804,000
Related allowance	855,000		451,000
With related allowance recorded, average recorded principal balance	8,068,000	4,165,000
Total unpaid principal balance	18,514,000		17,139,000
Total principal balance	18,503,000		17,134,000
Total average recorded principal balance	17,818,000	6,895,000
Originated Loan [Member] | Commercial Portfolio Segment [Member] | Commercial and Industrial [Member]
With no related allowance recorded, unpaid principal balance	9,577,000		8,604,000
With no related allowance recorded, principal balance	9,577,000		8,604,000
With no related allowance recorded, average recorded principal balance	9,091,000	206,000
With related allowance recorded, unpaid principal balance	5,509,000		5,011,000
With related allowance recorded, principal balance	5,506,000		5,011,000
Related allowance	546,000		83,000
With related allowance recorded, average recorded principal balance	5,258,000	2,561,000
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	91,000		94,000
With no related allowance recorded, principal balance	91,000		94,000
With no related allowance recorded, average recorded principal balance	92,000	17,000
With related allowance recorded, unpaid principal balance	0		0
With related allowance recorded, principal balance	0		0
Related allowance	0		0
With related allowance recorded, average recorded principal balance	0	0
Originated Loan [Member] | Commercial Portfolio Segment [Member] | Real Estate Owner Occupied Loan [Member]
With no related allowance recorded, unpaid principal balance	503,000		632,000
With no related allowance recorded, principal balance	502,000		632,000
With no related allowance recorded, average recorded principal balance	567,000	2,164,000
With related allowance recorded, unpaid principal balance	2,696,000		2,658,000
With related allowance recorded, principal balance	2,696,000		2,658,000
Related allowance	308,000		363,000
With related allowance recorded, average recorded principal balance	2,677,000	1,532,000
Originated Loan [Member] | Commercial Portfolio Segment [Member] | Real Estate Non Owner Occupied Loan [Member]
With no related allowance recorded, unpaid principal balance	0		0
With no related allowance recorded, principal balance	0		0
With no related allowance recorded, average recorded principal balance	0	0
With related allowance recorded, unpaid principal balance	0		0
With related allowance recorded, principal balance	0		0
Related allowance	0		0
With related allowance recorded, average recorded principal balance	0	0
Originated Loan [Member] | Commercial Portfolio Segment [Member] | Real Estate Multi Family and Residential Rental Loan [Member]
With no related allowance recorded, unpaid principal balance	0		0
With no related allowance recorded, principal balance	0		0
With no related allowance recorded, average recorded principal balance	0	343,000
With related allowance recorded, unpaid principal balance	138,000		140,000
With related allowance recorded, principal balance	131,000		135,000
Related allowance	1,000		5,000
With related allowance recorded, average recorded principal balance	133,000	72,000
Originated Loan [Member] | Retail Portfolio Segment [Member]
With no related allowance recorded, unpaid principal balance	1,661,000		1,660,000
With no related allowance recorded, principal balance	971,000		976,000
With no related allowance recorded, average recorded principal balance	974,000	1,153,000
With related allowance recorded, unpaid principal balance	801,000		851,000
With related allowance recorded, principal balance	717,000		772,000
Related allowance	191,000		238,000
With related allowance recorded, average recorded principal balance	744,000	1,055,000
Total unpaid principal balance	2,462,000		2,511,000
Total principal balance	1,688,000		1,748,000
Total average recorded principal balance	1,718,000	2,208,000
Originated Loan [Member] | Retail Portfolio Segment [Member] | Home Equity and Other [Member]
With no related allowance recorded, unpaid principal balance	628,000		607,000
With no related allowance recorded, principal balance	607,000		586,000
With no related allowance recorded, average recorded principal balance	597,000	716,000
With related allowance recorded, unpaid principal balance	394,000		442,000
With related allowance recorded, principal balance	381,000		431,000
Related allowance	168,000		194,000
With related allowance recorded, average recorded principal balance	406,000	823,000
Originated Loan [Member] | Retail Portfolio Segment [Member] | One to Four Family Mortgages [Member]
With no related allowance recorded, unpaid principal balance	1,033,000		1,053,000
With no related allowance recorded, principal balance	364,000		390,000
With no related allowance recorded, average recorded principal balance	377,000	437,000
With related allowance recorded, unpaid principal balance	407,000		409,000
With related allowance recorded, principal balance	336,000		341,000
Related allowance	23,000		44,000
With related allowance recorded, average recorded principal balance	338,000	232,000
Acquired Loan [Member]
With no related allowance recorded, unpaid principal balance	4,505,000		4,518,000
With no related allowance recorded, principal balance	3,665,000		3,827,000
With no related allowance recorded, average recorded principal balance	3,747,000	4,588,000
With related allowance recorded, unpaid principal balance	1,272,000		1,415,000
With related allowance recorded, principal balance	1,230,000		1,337,000
Related allowance	225,000		310,000
With related allowance recorded, average recorded principal balance	1,284,000	799,000
Total unpaid principal balance	5,777,000		5,933,000
Total principal balance	4,895,000		5,164,000
Total average recorded principal balance	5,031,000	5,387,000
Acquired Loan [Member] | Commercial Portfolio Segment [Member]
With no related allowance recorded, unpaid principal balance	1,353,000		1,636,000
With no related allowance recorded, principal balance	1,317,000		1,617,000
With no related allowance recorded, average recorded principal balance	1,468,000	1,930,000
With related allowance recorded, unpaid principal balance	491,000		535,000
With related allowance recorded, principal balance	483,000		526,000
Related allowance	27,000		43,000
With related allowance recorded, average recorded principal balance	505,000	799,000
Total unpaid principal balance	1,844,000		2,171,000
Total principal balance	1,800,000		2,143,000
Total average recorded principal balance	1,973,000	2,729,000
Acquired Loan [Member] | Commercial Portfolio Segment [Member] | Commercial and Industrial [Member]
With no related allowance recorded, unpaid principal balance	394,000		398,000
With no related allowance recorded, principal balance	394,000		398,000
With no related allowance recorded, average recorded principal balance	396,000	877,000
With related allowance recorded, unpaid principal balance	157,000		175,000
With related allowance recorded, principal balance	149,000		166,000
Related allowance	27,000		43,000
With related allowance recorded, average recorded principal balance	158,000	0
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
With no related allowance recorded, principal balance	0		0
With no related allowance recorded, average recorded principal balance	0	0
With related allowance recorded, unpaid principal balance	0		0
With related allowance recorded, principal balance	0		0
Related allowance	0		0
With related allowance recorded, average recorded principal balance	0	0
Acquired Loan [Member] | Commercial Portfolio Segment [Member] | Real Estate Owner Occupied Loan [Member]
With no related allowance recorded, unpaid principal balance	853,000		1,193,000
With no related allowance recorded, principal balance	837,000		1,193,000
With no related allowance recorded, average recorded principal balance	1,015,000	687,000
With related allowance recorded, unpaid principal balance	145,000		147,000
With related allowance recorded, principal balance	145,000		147,000
Related allowance	0		0
With related allowance recorded, average recorded principal balance	146,000	799,000
Acquired Loan [Member] | Commercial Portfolio Segment [Member] | Real Estate Non Owner Occupied Loan [Member]
With no related allowance recorded, unpaid principal balance	61,000		0
With no related allowance recorded, principal balance	61,000		0
With no related allowance recorded, average recorded principal balance	31,000	235,000
With related allowance recorded, unpaid principal balance	189,000		210,000
With related allowance recorded, principal balance	189,000		210,000
Related allowance	0		0
With related allowance recorded, average recorded principal balance	199,000	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	45,000		45,000
With no related allowance recorded, principal balance	25,000		26,000
With no related allowance recorded, average recorded principal balance	26,000	131,000
With related allowance recorded, unpaid principal balance	0		3,000
With related allowance recorded, principal balance	0		3,000
Related allowance	0		0
With related allowance recorded, average recorded principal balance	2,000	0
Acquired Loan [Member] | Retail Portfolio Segment [Member]
With no related allowance recorded, unpaid principal balance	3,152,000		2,882,000
With no related allowance recorded, principal balance	2,348,000		2,210,000
With no related allowance recorded, average recorded principal balance	2,279,000	2,658,000
With related allowance recorded, unpaid principal balance	781,000		880,000
With related allowance recorded, principal balance	747,000		811,000
Related allowance	198,000		267,000
With related allowance recorded, average recorded principal balance	779,000	0
Total unpaid principal balance	3,933,000		3,762,000
Total principal balance	3,095,000		3,021,000
Total average recorded principal balance	3,058,000	2,658,000
Acquired Loan [Member] | Retail Portfolio Segment [Member] | Home Equity and Other [Member]
With no related allowance recorded, unpaid principal balance	609,000		388,000
With no related allowance recorded, principal balance	569,000		361,000
With no related allowance recorded, average recorded principal balance	465,000	578,000
With related allowance recorded, unpaid principal balance	301,000		462,000
With related allowance recorded, principal balance	298,000		440,000
Related allowance	123,000		178,000
With related allowance recorded, average recorded principal balance	369,000	0
Acquired Loan [Member] | Retail Portfolio Segment [Member] | One to Four Family Mortgages [Member]
With no related allowance recorded, unpaid principal balance	2,543,000		2,494,000
With no related allowance recorded, principal balance	1,779,000		1,849,000
With no related allowance recorded, average recorded principal balance	1,814,000	2,080,000
With related allowance recorded, unpaid principal balance	480,000		418,000
With related allowance recorded, principal balance	449,000		371,000
Related allowance	75,000		$ 89,000
With related allowance recorded, average recorded principal balance	$ 410,000	$ 0