Note 5 - Allowances for Loan Losses - Impaired Loans Additional Information (Details) - USD ($)	12 Months Ended
Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
With no related allowance recorded - Average recorded investment	$ 15,445,000	$ 17,612,000	$ 12,467,000
With no related allowance recorded - Interest income recognized	333,000	381,000	484,000
With related allowance recorded - Average recorded investment	10,250,000	11,923,000	20,484,000
With related allowance recorded - Interest income recognized	169,000	135,000	130,000
Average recorded investment	25,695,000	29,535,000	32,951,000
Interest income recognized	502,000	516,000	614,000
Commercial Real Estate Portfolio Segment [Member]
With no related allowance recorded - Average recorded investment	12,033,000	12,796,000	7,739,000
With no related allowance recorded - Interest income recognized	264,000	282,000	450,000
With related allowance recorded - Average recorded investment	4,455,000	5,544,000	13,197,000
With related allowance recorded - Interest income recognized	52,000	13,000	5,000
Average recorded investment	16,488,000	18,340,000	20,936,000
Interest income recognized	316,000	295,000	455,000
Construction and Land Development Portfolio Segment [Member]
With no related allowance recorded - Average recorded investment	58,000	206,000	462,000
With no related allowance recorded - Interest income recognized		2,000
With related allowance recorded - Average recorded investment	12,000	90,000	557,000
With related allowance recorded - Interest income recognized
Average recorded investment	70,000	296,000	1,019,000
Interest income recognized		2,000
Commercial Portfolio Segment [Member]
With no related allowance recorded - Average recorded investment	1,828,000	3,225,000	3,070,000
With no related allowance recorded - Interest income recognized	42,000	78,000	22,000
With related allowance recorded - Average recorded investment	3,357,000	2,587,000	3,244,000
With related allowance recorded - Interest income recognized	74,000	28,000
Average recorded investment	5,185,000	5,812,000	6,314,000
Interest income recognized	116,000	106,000	22,000
Owner Occupied Real Estate [Member]
With no related allowance recorded - Average recorded investment	642,000	700,000	714,000
With no related allowance recorded - Interest income recognized	10,000	6,000	8,000
With related allowance recorded - Average recorded investment	2,104,000	3,643,000	3,446,000
With related allowance recorded - Interest income recognized	31,000	92,000	125,000
Average recorded investment	2,746,000	4,343,000	4,160,000
Interest income recognized	41,000	98,000	133,000
Consumer Portfolio Segment [Member]
With no related allowance recorded - Average recorded investment	858,000	685,000	482,000
With no related allowance recorded - Interest income recognized	16,000	13,000	4,000
With related allowance recorded - Average recorded investment	322,000	59,000	40,000
With related allowance recorded - Interest income recognized	12,000	2,000
Average recorded investment	1,180,000	744,000	522,000
Interest income recognized	28,000	15,000	4,000
Residential Portfolio Segment [Member]
With no related allowance recorded - Average recorded investment	26,000
With no related allowance recorded - Interest income recognized	1,000
With related allowance recorded - Average recorded investment
With related allowance recorded - Interest income recognized
Average recorded investment	26,000
Interest income recognized	$ 1,000

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 17
-URI http://asc.fasb.org/extlink&oid=66008989&loc=d3e5258-111524

Reference 2: 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

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