Note 4 - Allowance for Loan Losses, Nonperforming Assets and Impaired Loans - Loans Past Due 90 Days or More and Impaired Loans (Details) - USD ($) $ in Thousands		6 Months Ended			12 Months Ended
		Jun. 30, 2016		Jun. 30, 2015	Dec. 31, 2015
Loans past due 90 days or more and still accruing		$ 316	[1]	$ 80	$ 156
Ratio of loans past due 90 days or more and still accruing to loans, net of unearned income and deferred fees		0.05%		0.01%	0.03%
Accruing restructured loans		$ 4,729		$ 5,943	$ 8,814
Impaired loans with no valuation allowance		8,902	[2],[3]	12,182	12,973	[2],[3]
Impaired loans with a valuation allowance		1,798	[2],[3]	2,503	2,373	[2],[3]
Total impaired loans		10,700	[2],[3]	14,685	15,346	[2],[3]
Valuation allowance		(71)	[2]	(151)	(45)	[2]
Impaired loans, net of allowance		10,629		14,534	15,301
Average recorded investment in impaired loans(1)	[4],[5],[6]	14,147		15,543	17,297
Interest income recognized on impaired loans, after designation as impaired	[4]	$ 149		$ 172	$ 769

[1] Only classes with past-due or nonaccrual loans are shown.

[2] Only classes with impaired loans are shown.

[3] Recorded investment is net of charge-offs and interest paid while a loan is in nonaccrual status.

[4] Only classes with impaired loans are shown.

[5] Recorded investment is net of charge-offs and interest paid while a loan is in nonaccrual status.

[6] Recorded investment is net of charge-offs and interest paid while a loan is in nonaccrual status.