Note 15 - Disclosures About Fair Value of Financial Instruments (Details) - Estimated Fair Values and Related Carrying Amounts of Financial Instruments (USD $) In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Financial assets:
Financial Assets, Carrying Amount	$ 4,643,354	$ 4,383,100
Financial liabilities:
Financial Liabilities, Carrying Amount	4,149,035	3,979,268
Non-Interest Bearing Transaction Accounts [Member] | Fair Value, Inputs, Level 2 [Member]
Financial liabilities:
Financial Liabilities, Fair Value Measurement	889,260	718,438
Non-Interest Bearing Transaction Accounts [Member]
Financial liabilities:
Financial Liabilities, Carrying Amount	889,260	718,438
Financial Liabilities, Fair Value Measurement	889,260	718,438
Interest Bearing Transaction Accounts and Savings Deposits [Member] | Fair Value, Inputs, Level 2 [Member]
Financial liabilities:
Financial Liabilities, Fair Value Measurement	2,006,271	1,862,618
Interest Bearing Transaction Accounts and Savings Deposits [Member]
Financial liabilities:
Financial Liabilities, Carrying Amount	2,006,271	1,862,618
Financial Liabilities, Fair Value Measurement	2,006,271	1,862,618
Time Deposits [Member] | Fair Value, Inputs, Level 3 [Member]
Financial liabilities:
Financial Liabilities, Fair Value Measurement	967,900	1,120,035
Time Deposits [Member]
Financial liabilities:
Financial Liabilities, Carrying Amount	965,187	1,116,511
Financial Liabilities, Fair Value Measurement	967,900	1,120,035
Federal Funds Purchased and Securities Sold under Agreements to Repurchase [Member] | Fair Value, Inputs, Level 2 [Member]
Financial liabilities:
Financial Liabilities, Fair Value Measurement	110,586	107,887
Federal Funds Purchased and Securities Sold under Agreements to Repurchase [Member]
Financial liabilities:
Financial Liabilities, Carrying Amount	110,586	107,887
Financial Liabilities, Fair Value Measurement	110,586	107,887
Other Borrowings [Member] | Fair Value, Inputs, Level 2 [Member]
Financial liabilities:
Financial Liabilities, Fair Value Measurement	114,698	117,160
Other Borrowings [Member]
Financial liabilities:
Financial Liabilities, Carrying Amount	114,682	117,090
Financial Liabilities, Fair Value Measurement	115,000	117,160
Subordinated Debentures [Member] | Fair Value, Inputs, Level 2 [Member]
Financial liabilities:
Financial Liabilities, Fair Value Measurement	16,115	12,991
Subordinated Debentures [Member]
Financial liabilities:
Financial Liabilities, Carrying Amount	20,620	20,620
Financial Liabilities, Fair Value Measurement	16,115	12,991
Interest Payable [Member] | Fair Value, Inputs, Level 2 [Member]
Financial liabilities:
Financial Liabilities, Fair Value Measurement	1,147	1,450
Interest Payable [Member]
Financial liabilities:
Financial Liabilities, Carrying Amount	1,147	1,450
Financial Liabilities, Fair Value Measurement	1,147	1,450
Fair Value, Inputs, Level 1 [Member] | Cash and Cash Equivalents [Member]
Financial assets:
Financial Assets, Fair Value Measurement	335,909	539,380
Fair Value, Inputs, Level 2 [Member] | Held-to-Maturity Securities [Member]
Financial assets:
Financial Assets, Fair Value Measurement	780,533	731,445
Fair Value, Inputs, Level 2 [Member] | Interest Receivable [Member]
Financial assets:
Financial Assets, Fair Value Measurement	16,774	15,654
Fair Value, Inputs, Level 3 [Member] | Mortgage Loans Held For Sale [Member]
Financial assets:
Financial Assets, Fair Value Measurement	21,265	9,494
Fair Value, Inputs, Level 3 [Member] | Loans1 [Member]
Financial assets:
Financial Assets, Fair Value Measurement	2,022,889	1,694,748
Fair Value, Inputs, Level 3 [Member] | Loans Acquired, Not Covered By FDIC Loss Share [Member]
Financial assets:
Financial Assets, Fair Value Measurement	560,651	513,676
Fair Value, Inputs, Level 3 [Member] | Loans Acquired, Covered by FDIC Loss Share [Member]
Financial assets:
Financial Assets, Fair Value Measurement	105,789	143,814
Fair Value, Inputs, Level 3 [Member] | FDIC Indemnification Asset [Member]
Financial assets:
Financial Assets, Fair Value Measurement	22,663	48,791
Cash and Cash Equivalents [Member]
Financial assets:
Financial Assets, Carrying Amount	335,909	539,380
Financial Assets, Fair Value Measurement	335,909	539,380
Held-to-Maturity Securities [Member]
Financial assets:
Financial Assets, Carrying Amount	777,587	745,688
Financial Assets, Fair Value Measurement	780,533	731,445
Mortgage Loans Held For Sale [Member]
Financial assets:
Financial Assets, Carrying Amount	21,265	9,494
Financial Assets, Fair Value Measurement	21,265	9,494
Interest Receivable [Member]
Financial assets:
Financial Assets, Carrying Amount	16,774	15,654
Financial Assets, Fair Value Measurement	16,774	15,654
Loans1 [Member]
Financial assets:
Financial Assets, Carrying Amount	2,024,693	1,715,196
Financial Assets, Fair Value Measurement	2,022,889	1,694,748
Loans Acquired, Not Covered By FDIC Loss Share [Member]
Financial assets:
Financial Assets, Carrying Amount	575,980	515,644
Financial Assets, Fair Value Measurement	560,651	513,676
Loans Acquired, Covered by FDIC Loss Share [Member]
Financial assets:
Financial Assets, Carrying Amount	106,933	146,653
Financial Assets, Fair Value Measurement	105,789	143,814
FDIC Indemnification Asset [Member]
Financial assets:
Financial Assets, Carrying Amount	22,663	48,791
Financial Assets, Fair Value Measurement	$ 22,663	$ 48,791