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	Jun. 30, 2013	Dec. 31, 2012
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investment securities held to maturity	$ 1,124,946	$ 1,184,557
Fair Value, Inputs, Level 1 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and due from banks	384,276	491,382
Investment securities held to maturity	2,266	3,275
Federal Home Loan Bank advances	25,834	26,150
Fair Value, Inputs, Level 2 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investment securities held to maturity	1,122,680	1,181,282
Deposits	3,509,113	3,589,921
Short-term borrowed funds	66,640	53,687
Term repurchase agreement	10,096	10,135
Debt financing	15,201	15,645
Fair Value, Inputs, Level 3 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Loans	1,922,777	2,090,712
Other assets - FDIC indemnification receivable	8,756	13,834
Deposits	591,835	642,318
Reported Value Measurement [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and due from banks	384,276	491,382
Investment securities held to maturity	1,134,615	1,156,041
Loans	1,908,415	2,081,123
Other assets - FDIC indemnification receivable	8,758	13,847
Deposits	4,101,394	4,232,492
Short-term borrowed funds	66,640	53,687
Federal Home Loan Bank advances	25,687	25,799
Term repurchase agreement	10,000	10,000
Debt financing	15,000	15,000
Estimate of Fair Value Measurement [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and due from banks	384,276	491,382
Investment securities held to maturity	1,124,946	1,184,557
Loans	1,922,777	2,090,712
Other assets - FDIC indemnification receivable	8,756	13,834
Deposits	4,100,948	4,232,239
Short-term borrowed funds	66,640	53,687
Federal Home Loan Bank advances	25,834	26,150
Term repurchase agreement	10,096	10,135
Debt financing	$ 15,201	$ 15,645