Note 9 - Allowance for Loan Losses and Credit Quality Information - Troubled Debt Restructurings that Subsequently Defaulted (Details)	3 Months Ended		9 Months Ended
	Sep. 30, 2016 USD ($)	Sep. 30, 2015	Sep. 30, 2016 USD ($)	Sep. 30, 2015
Commercial Real Estate Portfolio Segment [Member] | Commercial Real Estate Other [Member]
Number of Contracts that subsequently defaulted	0		1
Outstanding Recorded Investment	$ 0		$ 183,000
Consumer Portfolio Segment [Member]
Number of Contracts that subsequently defaulted	3		3
Outstanding Recorded Investment	$ 6,000		$ 6,000
Commercial Portfolio Segment [Member] | Commercial Business Other [Member]
Number of Contracts that subsequently defaulted	0		1
Outstanding Recorded Investment	$ 0		$ 44,000
Number of Contracts that subsequently defaulted	3	0	5	0
Outstanding Recorded Investment	$ 6,000		$ 233,000