Note 3 - Loans and Allowance for Loan Losses - Impaired Loans (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019
With no related allowance recorded, unpaid principal balance	$ 15,774,000		$ 15,774,000		$ 13,687,000
With no related allowance recorded, principal balance	13,558,000		13,558,000		12,245,000
With no related allowance recorded, average recorded principal balance	15,506,000	$ 21,098,000	15,459,000	$ 17,785,000
With related allowance recorded, unpaid principal balance	2,596,000		2,596,000		2,398,000
With related allowance recorded, principal balance	2,547,000		2,547,000		2,377,000
Related allowance	910,000		910,000		1,623,000
With related allowance recorded, average recorded principal balance	2,667,000	10,798,000	2,870,000	10,446,000
Total unpaid principal balance	18,370,000		18,370,000		16,085,000
Total principal balance	16,105,000		16,105,000		14,622,000
Total average recorded principal balance	18,173,000	31,896,000	18,329,000	28,231,000
Commercial Portfolio Segment [Member]
With no related allowance recorded, unpaid principal balance	9,908,000		9,908,000		9,136,000
With no related allowance recorded, principal balance	9,783,000		9,783,000		9,068,000
With no related allowance recorded, average recorded principal balance	11,696,000	17,735,000	11,771,000	14,477,000
With related allowance recorded, unpaid principal balance	1,573,000		1,573,000		1,538,000
With related allowance recorded, principal balance	1,540,000		1,540,000		1,536,000
Related allowance	480,000		480,000		1,184,000
With related allowance recorded, average recorded principal balance	1,544,000	9,447,000	1,846,000	9,009,000
Total unpaid principal balance	11,481,000		11,481,000		10,674,000
Total principal balance	11,323,000		11,323,000		10,604,000
Total average recorded principal balance	13,240,000	27,182,000	13,617,000	23,486,000
Commercial Portfolio Segment [Member] | Commercial and Industrial [Member]
With no related allowance recorded, unpaid principal balance	6,109,000		6,109,000		8,129,000
With no related allowance recorded, principal balance	6,078,000		6,078,000		8,129,000
With no related allowance recorded, average recorded principal balance	7,416,000	15,474,000	8,282,000	12,480,000
With related allowance recorded, unpaid principal balance	557,000		557,000		460,000
With related allowance recorded, principal balance	551,000		551,000		458,000
Related allowance	242,000		242,000		202,000
With related allowance recorded, average recorded principal balance	940,000	8,629,000	1,128,000	7,022,000
Commercial Portfolio Segment [Member] | Vacant Land and Land Development and Residential Construction Loan [Member]
With no related allowance recorded, unpaid principal balance	283,000		283,000		85,000
With no related allowance recorded, principal balance	198,000		198,000		85,000
With no related allowance recorded, average recorded principal balance	326,000	88,000	234,000	90,000
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	96,000	0
Commercial Portfolio Segment [Member] | Real Estate Owner Occupied Loan [Member]
With no related allowance recorded, unpaid principal balance	2,923,000		2,923,000		715,000
With no related allowance recorded, principal balance	2,915,000		2,915,000		667,000
With no related allowance recorded, average recorded principal balance	3,645,000	1,883,000	3,053,000	1,733,000
With related allowance recorded, unpaid principal balance	850,000		850,000		1,078,000
With related allowance recorded, principal balance	823,000		823,000		1,078,000
Related allowance	235,000		235,000		982,000
With related allowance recorded, average recorded principal balance	436,000	818,000	538,000	1,820,000
Commercial Portfolio Segment [Member] | Real Estate Non Owner Occupied Loan [Member]
With no related allowance recorded, unpaid principal balance	593,000		593,000		178,000
With no related allowance recorded, principal balance	592,000		592,000		178,000
With no related allowance recorded, average recorded principal balance	309,000	209,000	199,000	120,000
With related allowance recorded, unpaid principal balance	166,000		166,000		0
With related allowance recorded, principal balance	166,000		166,000		0
Related allowance	3,000		3,000		0
With related allowance recorded, average recorded principal balance	168,000	0	84,000	100,000
Commercial Portfolio Segment [Member] | Real Estate Multi Family and Residential Rental Loan [Member]
With no related allowance recorded, unpaid principal balance	0		0		29,000
With no related allowance recorded, principal balance	0		0		9,000
With no related allowance recorded, average recorded principal balance	0	81,000	3,000	54,000
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	67,000
Retail Portfolio Segment [Member]
With no related allowance recorded, unpaid principal balance	5,866,000		5,866,000		4,551,000
With no related allowance recorded, principal balance	3,775,000		3,775,000		3,177,000
With no related allowance recorded, average recorded principal balance	3,810,000	3,363,000	3,688,000	3,308,000
With related allowance recorded, unpaid principal balance	1,023,000		1,023,000		860,000
With related allowance recorded, principal balance	1,007,000		1,007,000		841,000
Related allowance	430,000		430,000		439,000
With related allowance recorded, average recorded principal balance	1,123,000	1,351,000	1,024,000	1,437,000
Total unpaid principal balance	6,889,000		6,889,000		5,411,000
Total principal balance	4,782,000		4,782,000		4,018,000
Total average recorded principal balance	4,933,000	4,714,000	4,712,000	4,745,000
Retail Portfolio Segment [Member] | Home Equity and Other [Member]
With no related allowance recorded, unpaid principal balance	1,423,000		1,423,000		1,279,000
With no related allowance recorded, principal balance	1,336,000		1,336,000		1,209,000
With no related allowance recorded, average recorded principal balance	1,305,000	1,342,000	1,273,000	1,202,000
With related allowance recorded, unpaid principal balance	379,000		379,000		502,000
With related allowance recorded, principal balance	363,000		363,000		485,000
Related allowance	277,000		277,000		356,000
With related allowance recorded, average recorded principal balance	470,000	628,000	455,000	701,000
Retail Portfolio Segment [Member] | One to Four Family Mortgages [Member]
With no related allowance recorded, unpaid principal balance	4,443,000		4,443,000		3,272,000
With no related allowance recorded, principal balance	2,439,000		2,439,000		1,968,000
With no related allowance recorded, average recorded principal balance	2,505,000	2,021,000	2,415,000	2,106,000
With related allowance recorded, unpaid principal balance	644,000		644,000		358,000
With related allowance recorded, principal balance	644,000		644,000		356,000
Related allowance	153,000		153,000		$ 83,000
With related allowance recorded, average recorded principal balance	$ 653,000	$ 723,000	$ 569,000	$ 736,000