Note 9 - Allowance for Loan Losses and Credit Quality Information - Financial Effects of Troubled Debt Restructurings (Details) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017 USD ($)	Jun. 30, 2016 USD ($)	Jun. 30, 2017 USD ($)	Jun. 30, 2016 USD ($)
Pre- modification Outstanding Recorded Investment	$ 314	$ 100	$ 640	$ 207
Post- modification Outstanding Recorded Investment	$ 315	$ 100	$ 874	$ 208
Number of Contracts	5	6	10	12
Residential Portfolio Segment [Member]
Pre- modification Outstanding Recorded Investment	$ 0	$ 65	$ 282	$ 65
Post- modification Outstanding Recorded Investment	$ 0	$ 65	$ 514	$ 65
Number of Contracts	0	1	3	1
Consumer Portfolio Segment [Member]
Pre- modification Outstanding Recorded Investment	$ 314	$ 35	$ 358	$ 142
Post- modification Outstanding Recorded Investment	$ 315	$ 35	$ 360	$ 143
Number of Contracts	5	5	7	11