Note 9 - Fair Value Measurements (Details) - Fair Value Estimates for Financial Instruments, Excluding Financial Instruments Recorded at fair value on a recurring basis (USD $) In Thousands, unless otherwise specified	Sep. 30, 2014	Dec. 31, 2013
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investment securities held to maturity	$ 1,041,385	$ 1,112,676
Fair Value, Inputs, Level 1 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and due from banks	524,338	472,028
Investment securities held to maturity	1,164	1,597
Financial Liabilities:
Federal Home Loan Bank advances	20,161	20,558
Fair Value, Inputs, Level 2 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investment securities held to maturity	1,040,221	1,111,079
Financial Liabilities:
Deposits	3,900,497	3,671,014
Short-term borrowed funds	76,943	62,668
Term repurchase agreement		10,054
Fair Value, Inputs, Level 3 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Loans	1,701,539	1,800,625
Other assets - FDIC indemnification receivable		4,032
Financial Liabilities:
Deposits	419,195	491,921
Reported Value Measurement [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and due from banks	524,338	472,028
Investment securities held to maturity	1,035,041	1,132,299
Loans	1,700,613	1,796,051
Other assets - FDIC indemnification receivable		4,032
Financial Liabilities:
Deposits	4,321,638	4,163,781
Short-term borrowed funds	76,943	62,668
Federal Home Loan Bank advances	20,156	20,577
Term repurchase agreement		10,000
Estimate of Fair Value Measurement [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and due from banks	524,338	472,028
Investment securities held to maturity	1,041,385	1,112,676
Loans	1,701,539	1,800,625
Other assets - FDIC indemnification receivable		4,032
Financial Liabilities:
Deposits	4,319,692	4,162,935
Short-term borrowed funds	76,943	62,668
Federal Home Loan Bank advances	20,161	20,558
Term repurchase agreement		$ 10,054