Note 18 - Fair Value Measurements (Detail) - Estimated Fair Values and Related Carrying Amounts of Financial Instruments (USD $) In Thousands, unless otherwise specified	Mar. 31, 2013	Dec. 31, 2012
Financial assets:
Financial Assets, Carrying Amount	$ 3,543,561	$ 3,527,489
Financial liabilities:
Financial Liabilities, Carrying Amount	3,137,107	3,121,427
Non-Interest Bearing Transaction Accounts [Member] | Fair Value, Inputs, Level 2 [Member]
Financial liabilities:
Financial Liabilities, Fair Value Measurement	592,442	576,655
Non-Interest Bearing Transaction Accounts [Member]
Financial liabilities:
Financial Liabilities, Carrying Amount	592,442	576,655
Financial Liabilities, Fair Value Measurement	592,442	576,655
Interest Bearing Transaction Accounts and Savings Deposits [Member] | Fair Value, Inputs, Level 2 [Member]
Financial liabilities:
Financial Liabilities, Fair Value Measurement	1,456,005	1,421,137
Interest Bearing Transaction Accounts and Savings Deposits [Member]
Financial liabilities:
Financial Liabilities, Carrying Amount	1,456,005	1,421,137
Financial Liabilities, Fair Value Measurement	1,456,005	1,421,137
Time Deposits [Member] | Fair Value, Inputs, Level 3 [Member]
Financial liabilities:
Financial Liabilities, Fair Value Measurement	847,962	880,201
Time Deposits [Member]
Financial liabilities:
Financial Liabilities, Carrying Amount	844,217	876,371
Financial Liabilities, Fair Value Measurement	847,962	880,201
Federal Funds Purchased and Securities Sold under Agreements to Repurchase [Member] | Fair Value, Inputs, Level 2 [Member]
Financial liabilities:
Financial Liabilities, Fair Value Measurement	108,227	104,078
Federal Funds Purchased and Securities Sold under Agreements to Repurchase [Member]
Financial liabilities:
Financial Liabilities, Carrying Amount	108,227	104,078
Financial Liabilities, Fair Value Measurement	108,227	104,078
Other Borrowings [Member] | Fair Value, Inputs, Level 2 [Member]
Financial liabilities:
Financial Liabilities, Fair Value Measurement	86,816	94,472
Other Borrowings [Member]
Financial liabilities:
Financial Liabilities, Carrying Amount	81,646	89,441
Financial Liabilities, Fair Value Measurement	86,816	94,472
Subordinated Debentures [Member] | Fair Value, Inputs, Level 2 [Member]
Financial liabilities:
Financial Liabilities, Fair Value Measurement	15,793	15,414
Subordinated Debentures [Member]
Financial liabilities:
Financial Liabilities, Carrying Amount	20,620	20,620
Financial Liabilities, Fair Value Measurement	15,793	15,414
Interet Payable [Member] | Fair Value, Inputs, Level 2 [Member]
Financial liabilities:
Financial Liabilities, Fair Value Measurement	1,167	1,096
Interet Payable [Member]
Financial liabilities:
Financial Liabilities, Carrying Amount	1,167	1,096
Financial Liabilities, Fair Value Measurement	1,167	1,096
Cash and Cash Equivalents [Member] | Fair Value, Inputs, Level 1 [Member]
Financial assets:
Financial Assets, Fair Value Measurement	642,998	537,797
Cash and Cash Equivalents [Member]
Financial assets:
Financial Assets, Carrying Amount	642,998	537,797
Financial Assets, Fair Value Measurement	642,998	537,797
Held-to-Maturity Securities [Member] | Fair Value, Inputs, Level 2 [Member]
Financial assets:
Financial Assets, Fair Value Measurement	491,556	500,578
Held-to-Maturity Securities [Member]
Financial assets:
Financial Assets, Carrying Amount	488,513	496,141
Financial Assets, Fair Value Measurement	491,556	500,578
Mortgage Loans Held For Sale [Member] | Fair Value, Inputs, Level 3 [Member]
Financial assets:
Financial Assets, Fair Value Measurement	19,100	25,367
Mortgage Loans Held For Sale [Member]
Financial assets:
Financial Assets, Carrying Amount	19,100	25,367
Financial Assets, Fair Value Measurement	19,100	25,367
Interest Receivable [Member] | Fair Value, Inputs, Level 2 [Member]
Financial assets:
Financial Assets, Fair Value Measurement	13,027	14,530
Interest Receivable [Member]
Financial assets:
Financial Assets, Carrying Amount	13,027	14,530
Financial Assets, Fair Value Measurement	13,027	14,530
Loans1 [Member] | Fair Value, Inputs, Level 3 [Member]
Financial assets:
Financial Assets, Fair Value Measurement	1,561,626	1,602,014
Loans1 [Member]
Financial assets:
Financial Assets, Carrying Amount	1,561,342	1,600,631
Financial Assets, Fair Value Measurement	1,561,626	1,602,014
Loans Acquired, Covered By FDIC Loss Share [Member] | Fair Value, Inputs, Level 3 [Member]
Financial assets:
Financial Assets, Fair Value Measurement	179,752	208,685
Loans Acquired, Covered By FDIC Loss Share [Member]
Financial assets:
Financial Assets, Carrying Amount	181,537	210,842
Financial Assets, Fair Value Measurement	179,752	208,685
Loans Acquired, Not Covered By FDIC Loss Share [Member] | Fair Value, Inputs, Level 3 [Member]
Financial assets:
Financial Assets, Fair Value Measurement	83,111	82,764
Loans Acquired, Not Covered By FDIC Loss Share [Member]
Financial assets:
Financial Assets, Carrying Amount	78,745	82,764
Financial Assets, Fair Value Measurement	83,111	82,764
FDIC Indemnification Asset [Member] | Fair Value, Inputs, Level 3 [Member]
Financial assets:
Financial Assets, Fair Value Measurement	71,002	75,286
FDIC Indemnification Asset [Member]
Financial assets:
Financial Assets, Carrying Amount	71,002	75,286
Financial Assets, Fair Value Measurement	$ 71,002	$ 75,286