Note 3 - Loans - Loans Individually Evaluated for Impairment (Details) - USD ($) $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2017	Dec. 31, 2016
Loans with no related allowance recorded, recorded investment	$ 3,952	$ 3,609
Loans with no related allowance recorded, unpaid principal balance	4,799	4,392
Loans with no related allowance recorded, average recorded investment	3,545	4,996
Loans with an allowance recorded, recorded investment	1,855	2,660
Loans with an allowance recorded, unpaid principal balance	2,389	3,135
Related allowance	722	1,267
Loans with an allowance recorded, average recorded investment	2,464	2,567
Recorded investment	5,807	6,269
Unpaid principal balance	7,188	7,527
Average recorded investment	6,009	7,563
Commercial and Industrial Portfolio Segment [Member]
Loans with no related allowance recorded, recorded investment	350	322
Loans with no related allowance recorded, unpaid principal balance	540	465
Loans with no related allowance recorded, average recorded investment	228	1,947
Loans with an allowance recorded, recorded investment	1,787	2,360
Loans with an allowance recorded, unpaid principal balance	2,321	2,835
Related allowance	654	1,207
Loans with an allowance recorded, average recorded investment	2,343	1,619
Recorded investment	2,137	2,682
Unpaid principal balance	2,861	3,300
Average recorded investment	2,571	3,566
Construction and Development Excluding Undeveloped Land Portfolio Segment [Member]
Loans with no related allowance recorded, recorded investment	737	538
Loans with no related allowance recorded, unpaid principal balance	907	708
Loans with no related allowance recorded, average recorded investment	533	108
Loans with an allowance recorded, recorded investment
Loans with an allowance recorded, unpaid principal balance
Related allowance
Loans with an allowance recorded, average recorded investment		182
Recorded investment	737	538
Unpaid principal balance	907	708
Average recorded investment	533	290
Undevelopment Land Portfolio Segment [Member]
Loans with no related allowance recorded, recorded investment	474	233
Loans with no related allowance recorded, unpaid principal balance	506	265
Loans with no related allowance recorded, average recorded investment	413	76
Loans with an allowance recorded, recorded investment		241
Loans with an allowance recorded, unpaid principal balance		241
Related allowance		1
Loans with an allowance recorded, average recorded investment	60	149
Recorded investment	474	474
Unpaid principal balance	506	506
Average recorded investment	473	225
Real Estate Mortgage Portfolio Segment [Member]
Loans with no related allowance recorded, recorded investment	2,391	2,516
Loans with no related allowance recorded, unpaid principal balance	2,829	2,954
Loans with no related allowance recorded, average recorded investment	2,371	2,847
Loans with an allowance recorded, recorded investment	12
Loans with an allowance recorded, unpaid principal balance	12
Related allowance	12
Loans with an allowance recorded, average recorded investment	3	554
Recorded investment	2,403	2,516
Unpaid principal balance	2,841	2,954
Average recorded investment	2,374	3,401
Real Estate Mortgage Portfolio Segment [Member] | Commercial Investment [Member]
Loans with no related allowance recorded, recorded investment	55	107
Loans with no related allowance recorded, unpaid principal balance	55	107
Loans with no related allowance recorded, average recorded investment	124	193
Loans with an allowance recorded, recorded investment
Loans with an allowance recorded, unpaid principal balance
Related allowance
Loans with an allowance recorded, average recorded investment
Recorded investment	55	107
Unpaid principal balance	55	107
Average recorded investment	124	193
Real Estate Mortgage Portfolio Segment [Member] | Owner Occupied Commercial [Member]
Loans with no related allowance recorded, recorded investment	1,470	1,042
Loans with no related allowance recorded, unpaid principal balance	1,908	1,479
Loans with no related allowance recorded, average recorded investment	1,264	1,356
Loans with an allowance recorded, recorded investment
Loans with an allowance recorded, unpaid principal balance
Related allowance
Loans with an allowance recorded, average recorded investment		554
Recorded investment	1,470	1,042
Unpaid principal balance	1,908	1,479
Average recorded investment	1,264	1,910
Real Estate Mortgage Portfolio Segment [Member] | One to Four Family Residential [Member]
Loans with no related allowance recorded, recorded investment	785	895
Loans with no related allowance recorded, unpaid principal balance	785	896
Loans with no related allowance recorded, average recorded investment	759	962
Loans with an allowance recorded, recorded investment	12
Loans with an allowance recorded, unpaid principal balance	12
Related allowance	12
Loans with an allowance recorded, average recorded investment	3
Recorded investment	797	895
Unpaid principal balance	797	896
Average recorded investment	762	962
Real Estate Mortgage Portfolio Segment [Member] | Home Equity First Lien [Member]
Loans with no related allowance recorded, recorded investment
Loans with no related allowance recorded, unpaid principal balance
Loans with no related allowance recorded, average recorded investment		3
Loans with an allowance recorded, recorded investment
Loans with an allowance recorded, unpaid principal balance
Related allowance
Loans with an allowance recorded, average recorded investment
Recorded investment
Unpaid principal balance
Average recorded investment		3
Real Estate Mortgage Portfolio Segment [Member] | Home Equity Junior Lien [Member]
Loans with no related allowance recorded, recorded investment	81	472
Loans with no related allowance recorded, unpaid principal balance	81	472
Loans with no related allowance recorded, average recorded investment	224	333
Loans with an allowance recorded, recorded investment
Loans with an allowance recorded, unpaid principal balance
Related allowance
Loans with an allowance recorded, average recorded investment
Recorded investment	81	472
Unpaid principal balance	81	472
Average recorded investment	224	333
Consumer Portfolio Segment [Member]
Loans with no related allowance recorded, recorded investment
Loans with no related allowance recorded, unpaid principal balance	17
Loans with no related allowance recorded, average recorded investment		18
Loans with an allowance recorded, recorded investment	56	59
Loans with an allowance recorded, unpaid principal balance	56	59
Related allowance	56	59
Loans with an allowance recorded, average recorded investment	58	63
Recorded investment	56	59
Unpaid principal balance	73	59
Average recorded investment	$ 58	$ 81