Note 5 - Loans and Allowance for Credit Losses - Impaired Loans (Details) - USD ($)	3 Months Ended	12 Months Ended
Mar. 31, 2016	Mar. 31, 2015	Dec. 31, 2015
Commercial Portfolio Segment [Member] \| Year to Date [Member]
Average Recorded Investment Year To Date	$ 12,920,000	$ 12,116,000	$ 9,973,000
Impaired Financing Receivable, Interest Income, Accrual Method	16,000		69,000
Commercial Portfolio Segment [Member]
Unpaid Contractual Principal Balance	17,305,000	$ 13,080,000	16,123,000
Recorded Investment With No Allowance	1,165,000	1,464,000	2,396,000
Recorded Investment With Allowance	11,996,000	9,793,000	10,283,000
Total Recorded Investment	13,161,000	11,257,000	12,679,000
Related Allowance	2,922,000	5,771,000	3,478,000
Income Producing Portfolio Segment [Member] \| Year to Date [Member]
Average Recorded Investment Year To Date	13,012,000		10,294,000
Impaired Financing Receivable, Interest Income, Accrual Method	58,000		354,000
Income Producing Portfolio Segment [Member]
Unpaid Contractual Principal Balance	19,905,000	10,668,000	6,811,000
Recorded Investment With No Allowance	5,143,000	8,753,000	1,190,000
Recorded Investment With Allowance	14,762,000	1,222,000	4,928,000
Total Recorded Investment	19,905,000	9,975,000	6,118,000
Related Allowance	868,000	568,000	1,033,000
Average Recorded Investment Year To Date		10,235,000
Impaired Financing Receivable, Interest Income, Accrual Method		35,000
Owner Occupied Portfolio Segment [Member] \| Year to Date [Member]
Average Recorded Investment Year To Date	$ 1,739,000		$ 1,810,000
Impaired Financing Receivable, Interest Income, Accrual Method
Owner Occupied Portfolio Segment [Member]
Unpaid Contractual Principal Balance	$ 1,724,000	1,867,000	$ 1,753,000
Recorded Investment With No Allowance	461,000	1,025,000	946,000
Recorded Investment With Allowance	1,263,000	842,000	807,000
Total Recorded Investment	1,724,000	1,867,000	1,753,000
Related Allowance	360,000	400,000	400,000
Average Recorded Investment Year To Date		$ 1,878,000
Impaired Financing Receivable, Interest Income, Accrual Method
Residential Portfolio Segment [Member] \| Year to Date [Member]
Average Recorded Investment Year To Date	$ 293,000	$ 344,000	$ 336,000
Impaired Financing Receivable, Interest Income, Accrual Method
Residential Portfolio Segment [Member]
Unpaid Contractual Principal Balance	$ 257,000	$ 342,000	$ 329,000
Recorded Investment With No Allowance	$ 257,000	$ 342,000	$ 329,000
Recorded Investment With Allowance
Total Recorded Investment	$ 257,000	$ 342,000	$ 329,000
Related Allowance
Construction Portfolio Segment [Member] \| Year to Date [Member]
Average Recorded Investment Year To Date	$ 7,938,000	$ 8,728,000	$ 7,594,000
Impaired Financing Receivable, Interest Income, Accrual Method		99,000	205,000
Construction Portfolio Segment [Member]
Unpaid Contractual Principal Balance	$ 5,422,000	8,671,000	10,454,000
Recorded Investment With No Allowance	4,870,000	8,071,000	4,877,000
Recorded Investment With Allowance	552,000	600,000	5,577,000
Total Recorded Investment	5,422,000	8,671,000	10,454,000
Related Allowance	310,000	550,000	950,000
Home Equity Portfolio Segment [Member] \| Year to Date [Member]
Average Recorded Investment Year To Date	$ 142,000	$ 1,144,000	$ 650,000
Impaired Financing Receivable, Interest Income, Accrual Method
Home Equity Portfolio Segment [Member]
Unpaid Contractual Principal Balance	$ 122,000	$ 889,000	$ 161,000
Recorded Investment With No Allowance		118,000	116,000
Recorded Investment With Allowance	$ 122,000	771,000	45,000
Total Recorded Investment	122,000	889,000	161,000
Related Allowance	88,000	289,000	38,000
Other Consumer Portfolio Segment [Member] \| Year to Date [Member]
Average Recorded Investment Year To Date	$ 11,000	$ 34,000	31,000
Impaired Financing Receivable, Interest Income, Accrual Method			1,000
Other Consumer Portfolio Segment [Member]
Unpaid Contractual Principal Balance		$ 10,000	22,000
Recorded Investment With No Allowance			19,000
Recorded Investment With Allowance		$ 10,000	3,000
Total Recorded Investment		10,000	22,000
Related Allowance		5,000	3,000
Year to Date [Member]
Average Recorded Investment Year To Date	$ 36,055,000	34,479,000	30,688,000
Impaired Financing Receivable, Interest Income, Accrual Method	74,000	134,000	629,000
Unpaid Contractual Principal Balance	44,735,000	35,527,000	35,653,000
Recorded Investment With No Allowance	11,896,000	19,773,000	9,873,000
Recorded Investment With Allowance	28,695,000	13,238,000	21,643,000
Total Recorded Investment	40,591,000	33,011,000	31,516,000
Related Allowance	4,548,000	$ 7,583,000	$ 5,902,000
Impaired Financing Receivable, Interest Income, Accrual Method	$ 74,000

Average amount of investment of impaired financing receivables with related allowance for credit losses and without a related allowance for credit losses.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 15
-Subparagraph (c)(1)
-URI http://asc.fasb.org/extlink&oid=66008989&loc=d3e5212-111524

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 17
-URI http://asc.fasb.org/extlink&oid=66008989&loc=d3e5258-111524

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+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 14A
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=66008989&loc=SL6953550-111524

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+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Glossary Recorded Investment
-URI http://asc.fasb.org/extlink&oid=65880944

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 15
-Subparagraph (a)(3)
-URI http://asc.fasb.org/extlink&oid=66008989&loc=d3e5212-111524

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