Note 5 - Loans - Troubled Debt Restructuring (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)
No. of Contracts	31	30	28
Pre-Modification Outstanding Recorded Investment	$ 77,741	$ 34,735	$ 19,907
Post-Modification Outstanding Recorded Investment	77,436	33,905	19,759
Special Reserve	1,556	1,780	752
Charge-offs	$ 305	$ 830	$ 148
Commercial Portfolio Segment [Member]
No. of Contracts	16	24	3
Pre-Modification Outstanding Recorded Investment	$ 29,590	$ 30,215	$ 1,181
Post-Modification Outstanding Recorded Investment	29,590	29,385	1,181
Special Reserve	7	1,746	2
Charge-offs		$ 830
Real Estate Construction Portfolio Segment [Member]
No. of Contracts	2
Pre-Modification Outstanding Recorded Investment	$ 27,683
Post-Modification Outstanding Recorded Investment	27,683
Special Reserve
Charge-offs
Commercial Real Estate Portfolio Segment [Member]
No. of Contracts	9	4	20
Pre-Modification Outstanding Recorded Investment	$ 19,380	$ 4,153	$ 17,204
Post-Modification Outstanding Recorded Investment	19,075	4,153	17,204
Special Reserve	1,496	34	708
Charge-offs	$ 305
Residential Mortgage and Equity Lines Portfolio Segment [Member]
No. of Contracts	4	2	5
Pre-Modification Outstanding Recorded Investment	$ 1,088	$ 367	$ 1,522
Post-Modification Outstanding Recorded Investment	1,088	367	1,374
Special Reserve	53		42
Charge-offs			$ 148