Note 3 - Loans and Allowance for Loan Losses - Activity for Troubled Debt Restructurings (Details) - USD ($)	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Commercial Portfolio Segment [Member] | Originated Loan [Member] | Commercial and Industrial [Member]
Beginning Balance	$ 2,989,000	$ 1,503,000
Charge-Offs	(230,000)	0
Payments	(882,000)	(125,000)
Transfers to ORE	0	0
Net Additions/Deletions	105,000	159,000
Ending Balance	1,982,000	1,537,000
Commercial Portfolio Segment [Member] | Originated Loan [Member] | Vacant Land and Land Development and Residential Construction Loan [Member]
Beginning Balance	383,000	1,488,000
Charge-Offs	0	0
Payments	(45,000)	(529,000)
Transfers to ORE	0	0
Net Additions/Deletions	0	0
Ending Balance	338,000	959,000
Commercial Portfolio Segment [Member] | Originated Loan [Member] | Real Estate Owner Occupied Loan [Member]
Beginning Balance	1,599,000	906,000
Charge-Offs	0	0
Payments	(855,000)	(27,000)
Transfers to ORE	0	0
Net Additions/Deletions	3,804,000	0
Ending Balance	4,548,000	879,000
Commercial Portfolio Segment [Member] | Originated Loan [Member] | Real Estate Non Owner Occupied Loan [Member]
Beginning Balance	0	5,110,000
Charge-Offs	0	0
Payments	0	(123,000)
Transfers to ORE	0	0
Net Additions/Deletions	0	(436,000)
Ending Balance	0	4,551,000
Commercial Portfolio Segment [Member] | Originated Loan [Member] | Real Estate Multi Family and Residential Rental Loan [Member]
Beginning Balance	0	716,000
Charge-Offs	0	0
Payments	0	(113,000)
Transfers to ORE	0	0
Net Additions/Deletions	0	(312,000)
Ending Balance	0	291,000
Commercial Portfolio Segment [Member] | Acquired Loan [Member] | Commercial and Industrial [Member]
Beginning Balance	1,001,000	1,125,000
Charge-Offs	(275,000)	0
Payments	(10,000)	(233,000)
Transfers to ORE	0	0
Net Additions/Deletions	0	30,000
Ending Balance	716,000	922,000
Commercial Portfolio Segment [Member] | Acquired Loan [Member] | Vacant Land and Land Development and Residential Construction Loan [Member]
Beginning Balance	0	0
Charge-Offs	0	0
Payments	0	0
Transfers to ORE	0	0
Net Additions/Deletions	0	0
Ending Balance	0	0
Commercial Portfolio Segment [Member] | Acquired Loan [Member] | Real Estate Owner Occupied Loan [Member]
Beginning Balance	427,000	900,000
Charge-Offs	0	(12,000)
Payments	(17,000)	0
Transfers to ORE	0	0
Net Additions/Deletions	1,597,000	108,000
Ending Balance	2,007,000	996,000
Commercial Portfolio Segment [Member] | Acquired Loan [Member] | Real Estate Non Owner Occupied Loan [Member]
Beginning Balance	237,000	728,000
Charge-Offs	0	0
Payments	(5,000)	(145,000)
Transfers to ORE	0	0
Net Additions/Deletions	0	0
Ending Balance	232,000	583,000
Commercial Portfolio Segment [Member] | Acquired Loan [Member] | Real Estate Multi Family and Residential Rental Loan [Member]
Beginning Balance	41,000	60,000
Charge-Offs	0	0
Payments	(5,000)	0
Transfers to ORE	0	0
Net Additions/Deletions	0	8,000
Ending Balance	36,000	68,000
Retail Portfolio Segment [Member] | Originated Loan [Member] | Home Equity and Other [Member]
Beginning Balance	1,127,000	385,000
Charge-Offs	0	0
Payments	(8,000)	0
Transfers to ORE	0	0
Net Additions/Deletions	50,000	321,000
Ending Balance	1,169,000	706,000
Retail Portfolio Segment [Member] | Originated Loan [Member] | One to Four Family Mortgages [Member]
Beginning Balance	146,000	157,000
Charge-Offs	0	0
Payments	(2,000)	(3,000)
Transfers to ORE	0	0
Net Additions/Deletions	0	0
Ending Balance	144,000	154,000
Retail Portfolio Segment [Member] | Acquired Loan [Member] | Home Equity and Other [Member]
Beginning Balance	219,000	208,000
Charge-Offs	(15,000)	0
Payments	(1,000)	(9,000)
Transfers to ORE	(82,000)	0
Net Additions/Deletions	119,000	7,000
Ending Balance	240,000	206,000
Retail Portfolio Segment [Member] | Acquired Loan [Member] | One to Four Family Mortgages [Member]
Beginning Balance	393,000	326,000
Charge-Offs	0	0
Payments	(9,000)	(4,000)
Transfers to ORE	0	0
Net Additions/Deletions	0	54,000
Ending Balance	$ 384,000	$ 376,000