Note 4 - Loans and Allowance for Loan Losses (Details) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014	Dec. 31, 2014
Receivables [Abstract]
Loans and Leases Receivable, Net of Deferred Income	$ 2,171,832,000		$ 2,171,832,000		$ 2,089,277,000
Loans and Leases Receivable, Period Increase (Decrease)			$ 82,600,000
Loans and Leases Receivable, Percentage, Period Increase (Decrease)			4.00%
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities, Outstanding Balance	29,400,000		$ 29,400,000
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities, Carrying Amount, Net	15,900,000		15,900,000
Impaired Financing Receivable, Interest Income, Accrual Method	400,000	$ 400,000	800,000	$ 800,000
Loans and Leases Receivable, Nonaccrual Loans, Interest Income Recognized	$ 0	$ 0	$ 0	$ 0
Minimum Number of Days Past Due at Period End for Loans Modified as Troubled Debt Restructurings			30 days