Note 3 - Loans and Allowance for Loan Losses (Details) - USD ($)	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015	Dec. 31, 2015
Receivables [Abstract]
Loans, credit exposure	$ 2,295,668,000		$ 2,277,727,000
Loans and Leases Receivable Period Increase Decrease	$ 17,900,000
Loans and Leases Receivable Percentage Period Increase Decrease	0.80%
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities, Outstanding Balance	$ 21,300,000		24,600,000
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities, Carrying Amount, Net	10,100,000		$ 13,100,000
Impaired Financing Receivable, Interest Income, Accrual Method	300,000	$ 400,000
Loans and Leases Receivable, Nonaccrual Loans Interest Income Recognized	$ 0	$ 0
Minimum Number of Days Past Due at Period End for Loans Modified as Troubled Debt Restructurings	30 days