Note 8 - Loans - Allowance for Loan Losses by Portfolio Segment (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Balance	$ 122,555	$ 122,084	$ 122,391	$ 123,279
Provision/(reversal) for possible credit losses	0	0	0	(3,000)
Charge-offs	(1,713)	(878)	(2,944)	(897)
Recoveries	1,809	693	3,204	2,517
Net (charge-offs)/recoveries	96	(185)	260	1,620
Balance	122,651	121,899	122,651	121,899
Reserve for impaired loans	1,686	3,833	1,686	3,833
Reserve for non-impaired loans	120,965	118,066	120,965	118,066
Reserve for off-balance sheet credit commitments	4,550	3,088	4,550	3,088
Commercial Portfolio Segment [Member]
Balance	54,750	54,597	54,978	49,796
Provision/(reversal) for possible credit losses	(100)	920	862	4,827
Charge-offs	(1,713)	(488)	(2,944)	(507)
Recoveries	1,356	150	1,397	1,063
Net (charge-offs)/recoveries	(357)	(338)	(1,547)	556
Balance	54,293	55,179	54,293	55,179
Reserve for impaired loans	832	2,463	832	2,463
Reserve for non-impaired loans	53,461	52,716	53,461	52,716
Reserve for off-balance sheet credit commitments	2,090	1,606	2,090	1,606
Real Estate Construction Portfolio Segment [Member]
Balance	20,723	21,864	19,626	24,838
Provision/(reversal) for possible credit losses	257	(1,245)	310	(4,263)
Charge-offs	0	0	0	0
Recoveries	30	44	1,074	88
Net (charge-offs)/recoveries	30	44	1,074	88
Balance	21,010	20,663	21,010	20,663
Reserve for impaired loans	0	0	0	0
Reserve for non-impaired loans	21,010	20,663	21,010	20,663
Reserve for off-balance sheet credit commitments	2,029	1,207	2,029	1,207
Commercial Real Estate Portfolio Segment [Member]
Balance	33,073	34,230	33,487	37,610
Provision/(reversal) for possible credit losses	(180)	(533)	(746)	(4,696)
Charge-offs	0	(161)	0	(161)
Recoveries	261	440	413	1,223
Net (charge-offs)/recoveries	261	279	413	1,062
Balance	33,154	33,976	33,154	33,976
Reserve for impaired loans	620	1,036	620	1,036
Reserve for non-impaired loans	32,534	32,940	32,534	32,940
Reserve for off-balance sheet credit commitments	137	77	137	77
Residential Mortgage and Equity Lines Portfolio Segment [Member]
Balance	13,975	11,372	14,282	11,013
Provision/(reversal) for possible credit losses	27	860	(438)	1,135
Charge-offs	0	(229)	0	(229)
Recoveries	162	59	320	143
Net (charge-offs)/recoveries	162	(170)	320	(86)
Balance	14,164	12,062	14,164	12,062
Reserve for impaired loans	234	334	234	334
Reserve for non-impaired loans	13,930	11,728	13,930	11,728
Reserve for off-balance sheet credit commitments	290	190	290	190
Installment and Other Loans [Member ]
Balance	34	21	18	22
Provision/(reversal) for possible credit losses	(4)	(2)	12	(3)
Charge-offs	0	0	0	0
Recoveries	0	0	0	0
Net (charge-offs)/recoveries	0	0	0	0
Balance	30	19	30	19
Reserve for impaired loans	0	0	0	0
Reserve for non-impaired loans	30	19	30	19
Reserve for off-balance sheet credit commitments	$ 4	$ 8	$ 4	$ 8