Note 18 - Assets and Liabilities Measured and Reported at Fair Value (Details Textual) - USD ($)	Mar. 31, 2017	Dec. 31, 2016
Impaired Financing Receivable, with Related Allowance, Recorded Investment	$ 2,702,000	$ 2,660,000
Impaired Financing Receivable, Related Allowance	1,188,000	1,267,000
Other Real Estate, Foreclosed Assets, and Repossessed Assets	4,000,000	5,000,000
Mortgage Servicing Rights [Member]
Impaired Financing Receivable, Related Allowance	0	0
Fair Value, Measurements, Recurring [Member]
Assets, Fair Value Disclosure	556,582,000	570,277,000
Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member]
Assets, Fair Value Disclosure	0	0
Financial and Nonfinancial Liabilities, Fair Value Disclosure	0	0
Impaired Loans [Member] | Appraisal Discount Method [Member]
Assets, Fair Value Disclosure	1,500,000	$ 1,400,000
Impaired Loans [Member] | Appraisal Discount Method [Member] | Fair Value, Inputs, Level 3 [Member]
Assets, Fair Value Disclosure	$ 1,754,000