Note 13 - Commitments and Contingencies (Details Textual) - USD ($)	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Commitments To Extend Notional Amount	$ 2,062,241,000	$ 1,971,848,000
Commitments to Fund Fixed Rate Loans	75,700,000
Commitments to Fund Adjustable Rate Loans	1,990,000,000
Operating Leases, Rent Expense	10,200,000	9,300,000	$ 8,200,000
Operating Leases, Income Statement, Sublease Revenue	$ 400,000	$ 300,000	$ 200,000
Minimum [Member]
Lessor Leasing Arrangements, Operating Leases, Term of Contract	1 year
Maximum [Member]
Lessor Leasing Arrangements, Operating Leases, Term of Contract	25 years