Note 4 - Loans and Allowance for Loan Losses (Details) (USD $)	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014	Dec. 31, 2014
Receivables [Abstract]
Loans and Leases Receivable, Net of Deferred Income	$ 2,120,760,000		$ 2,089,277,000
Loans and Leases Receivable, Period Increase (Decrease)	31,500,000
Loans and Leases Receivable, Percentage, Period Increase (Decrease)	1.50%
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities, Outstanding Balance	31,300,000
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities, Carrying Amount, Net	17,600,000
Impaired Financing Receivable, Interest Income, Accrual Method	400,000	500,000
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