Note 5 - Loans and Allowance for Loan Losses - Loans Restructured as TDRs, Excluding Loans Acquired, Segregated by Class of Loans (Details)	3 Months Ended		9 Months Ended
	Sep. 30, 2017 USD ($)	Sep. 30, 2016 USD ($)	Sep. 30, 2017 USD ($)	Sep. 30, 2016 USD ($)
Number of Loans	1	21	13	67
Balance Prior to TDR	$ 608,000	$ 3,011,000	$ 9,237,000	$ 13,372,000
Balance	607,000	2,923,000	9,225,000	13,222,000
Financial Impact on Date of Restructure			33,000
Extended Maturity [Member]
Balance	607,000	2,155,000	9,186,000	11,536,000
Contractual Interest Rate Reduction [Member]
Balance		$ 768,000	$ 39,000	$ 1,686,000
Commercial Real Estate Portfolio Segment [Member]
Number of Loans		15	3	49
Balance Prior to TDR		$ 1,577,000	$ 7,818,000	$ 11,335,000
Balance		1,528,000	7,818,000	11,252,000
Financial Impact on Date of Restructure			33,000
Commercial Real Estate Portfolio Segment [Member] | Extended Maturity [Member]
Balance		760,000	7,818,000	9,566,000
Commercial Real Estate Portfolio Segment [Member] | Contractual Interest Rate Reduction [Member]
Balance		$ 768,000		$ 1,686,000
Commercial Real Estate Portfolio Segment [Member] | Commercial Loans [Member]
Number of Loans	1
Balance Prior to TDR	$ 608,000
Balance	607,000
Financial Impact on Date of Restructure
Commercial Real Estate Portfolio Segment [Member] | Commercial Loans [Member] | Extended Maturity [Member]
Balance	607,000
Commercial Real Estate Portfolio Segment [Member] | Commercial Loans [Member] | Contractual Interest Rate Reduction [Member]
Balance
Commercial Real Estate Portfolio Segment [Member] | Single Family Residential Loans [Member]
Number of Loans		13	1	22
Balance Prior to TDR		$ 742,000	$ 456,000	$ 1,538,000
Balance		694,000	456,000	1,487,000
Financial Impact on Date of Restructure
Commercial Real Estate Portfolio Segment [Member] | Single Family Residential Loans [Member] | Extended Maturity [Member]
Balance		694,000	456,000	933,000
Commercial Real Estate Portfolio Segment [Member] | Single Family Residential Loans [Member] | Contractual Interest Rate Reduction [Member]
Balance				$ 554,000
Commercial Real Estate Portfolio Segment [Member] | Other Commercial Loans [Member]
Number of Loans		2	2	27
Balance Prior to TDR		$ 835,000	$ 7,362,000	$ 9,797,000
Balance		834,000	7,362,000	9,765,000
Financial Impact on Date of Restructure			33,000
Commercial Real Estate Portfolio Segment [Member] | Other Commercial Loans [Member] | Extended Maturity [Member]
Balance		66,000	7,362,000	8,633,000
Commercial Real Estate Portfolio Segment [Member] | Other Commercial Loans [Member] | Contractual Interest Rate Reduction [Member]
Balance		$ 768,000		$ 1,132,000
Commercial Portfolio Segment [Member]
Number of Loans	1	5	10	16
Balance Prior to TDR	$ 608,000	$ 1,387,000	$ 1,419,000	$ 1,987,000
Balance	607,000	1,387,000	1,407,000	1,959,000
Financial Impact on Date of Restructure
Commercial Portfolio Segment [Member] | Extended Maturity [Member]
Balance	607,000	1,387,000	1,368,000	1,959,000
Commercial Portfolio Segment [Member] | Contractual Interest Rate Reduction [Member]
Balance			$ 39,000
Commercial Portfolio Segment [Member] | Commercial Loans [Member]
Number of Loans		5	10	16
Balance Prior to TDR		$ 1,387,000	$ 1,419,000	$ 1,987,000
Balance		1,387,000	1,407,000	1,959,000
Financial Impact on Date of Restructure
Commercial Portfolio Segment [Member] | Commercial Loans [Member] | Extended Maturity [Member]
Balance		1,387,000	1,368,000	1,959,000
Commercial Portfolio Segment [Member] | Commercial Loans [Member] | Contractual Interest Rate Reduction [Member]
Balance			$ 39,000
Consumer Portfolio Segment [Member]
Number of Loans		1		2
Balance Prior to TDR		$ 47,000		$ 50,000
Balance		8,000		11,000
Financial Impact on Date of Restructure
Consumer Portfolio Segment [Member] | Extended Maturity [Member]
Balance		8,000		11,000
Consumer Portfolio Segment [Member] | Contractual Interest Rate Reduction [Member]
Balance
Consumer Portfolio Segment [Member] | Other Loans [Member]
Number of Loans		1		2
Balance Prior to TDR		$ 47,000		$ 50,000
Balance		8,000		11,000
Financial Impact on Date of Restructure
Consumer Portfolio Segment [Member] | Other Loans [Member] | Extended Maturity [Member]
Balance		8,000		11,000
Consumer Portfolio Segment [Member] | Other Loans [Member] | Contractual Interest Rate Reduction [Member]
Balance