Note 19 - Fair Value Measurements (Details) - Estimated Fair Values and Related Carrying Amounts of Financial Instruments (USD $) In Thousands, unless otherwise specified	Mar. 31, 2015	Dec. 31, 2014
Financial assets:
Financial Assets, Carrying Amount	$ 7,817,824	$ 4,643,354
Financial liabilities:
Financial Liabilities, Carrying Amount	6,804,087	4,149,035
Non-Interest Bearing Transaction Accounts [Member] | Fair Value, Inputs, Level 2 [Member]
Financial liabilities:
Financial Liabilities, Fair Value Measurement	1,123,966	889,260
Non-Interest Bearing Transaction Accounts [Member]
Financial liabilities:
Financial Liabilities, Carrying Amount	1,123,966	889,260
Financial Liabilities, Fair Value Measurement	1,123,966	889,260
Interest Bearing Transaction Accounts and Savings Deposits [Member] | Fair Value, Inputs, Level 2 [Member]
Financial liabilities:
Financial Liabilities, Fair Value Measurement	3,627,870	2,006,271
Interest Bearing Transaction Accounts and Savings Deposits [Member]
Financial liabilities:
Financial Liabilities, Carrying Amount	3,627,870	2,006,271
Financial Liabilities, Fair Value Measurement	3,627,870	2,006,271
Time Deposits [Member] | Fair Value, Inputs, Level 3 [Member]
Financial liabilities:
Financial Liabilities, Fair Value Measurement	1,523,149	967,900
Time Deposits [Member]
Financial liabilities:
Financial Liabilities, Carrying Amount	1,522,872	965,187
Financial Liabilities, Fair Value Measurement	1,523,149	967,900
Federal Funds Purchased and Securities Sold under Agreements to Repurchase [Member] | Fair Value, Inputs, Level 2 [Member]
Financial liabilities:
Financial Liabilities, Fair Value Measurement	111,484	110,586
Federal Funds Purchased and Securities Sold under Agreements to Repurchase [Member]
Financial liabilities:
Financial Liabilities, Carrying Amount	111,484	110,586
Financial Liabilities, Fair Value Measurement	111,484	110,586
Other Borrowings [Member] | Fair Value, Inputs, Level 2 [Member]
Financial liabilities:
Financial Liabilities, Fair Value Measurement	288,198	114,698
Other Borrowings [Member]
Financial liabilities:
Financial Liabilities, Carrying Amount	285,060	114,682
Financial Liabilities, Fair Value Measurement	288,198	114,698
Subordinated Debentures [Member] | Fair Value, Inputs, Level 2 [Member]
Financial liabilities:
Financial Liabilities, Fair Value Measurement	58,039	16,115
Subordinated Debentures [Member]
Financial liabilities:
Financial Liabilities, Carrying Amount	62,994	20,620
Financial Liabilities, Fair Value Measurement	58,039	16,115
Interest Payable [Member] | Fair Value, Inputs, Level 2 [Member]
Financial liabilities:
Financial Liabilities, Fair Value Measurement	2,445	1,147
Interest Payable [Member]
Financial liabilities:
Financial Liabilities, Carrying Amount	2,445	1,147
Financial Liabilities, Fair Value Measurement	2,445	1,147
Fair Value, Inputs, Level 1 [Member] | Cash and Cash Equivalents [Member]
Financial assets:
Financial Assets, Fair Value Measurement	685,828	335,909
Fair Value, Inputs, Level 2 [Member] | Interest Bearing Balances Due from Banks - Time [Member]
Financial assets:
Financial Assets, Fair Value Measurement	24,986
Fair Value, Inputs, Level 2 [Member] | Held-to-Maturity Securities [Member]
Financial assets:
Financial Assets, Fair Value Measurement	913,037	780,533
Fair Value, Inputs, Level 2 [Member] | Interest Receivable [Member]
Financial assets:
Financial Assets, Fair Value Measurement	24,719	16,774
Fair Value, Inputs, Level 3 [Member] | Mortgage Loans Held For Sale [Member]
Financial assets:
Financial Assets, Fair Value Measurement	25,513	21,265
Fair Value, Inputs, Level 3 [Member] | Loans1 [Member]
Financial assets:
Financial Assets, Fair Value Measurement	2,095,657	2,022,889
Fair Value, Inputs, Level 3 [Member] | Loans Acquired, Not Covered By FDIC Loss Share [Member]
Financial assets:
Financial Assets, Fair Value Measurement	2,429,407	560,651
Fair Value, Inputs, Level 3 [Member] | Loans Acquired, Covered by FDIC Loss Share [Member]
Financial assets:
Financial Assets, Fair Value Measurement	102,933	105,789
Fair Value, Inputs, Level 3 [Member] | FDIC Indemnification Asset [Member]
Financial assets:
Financial Assets, Fair Value Measurement	15,965	22,663
Cash and Cash Equivalents [Member]
Financial assets:
Financial Assets, Carrying Amount	685,828	335,909
Financial Assets, Fair Value Measurement	685,828	335,909
Interest Bearing Balances Due from Banks - Time [Member]
Financial assets:
Financial Assets, Carrying Amount	25,000
Financial Assets, Fair Value Measurement	24,986
Held-to-Maturity Securities [Member]
Financial assets:
Financial Assets, Carrying Amount	902,423	777,587
Financial Assets, Fair Value Measurement	913,037	780,533
Mortgage Loans Held For Sale [Member]
Financial assets:
Financial Assets, Carrying Amount	25,513	21,265
Financial Assets, Fair Value Measurement	25,513	21,265
Interest Receivable [Member]
Financial assets:
Financial Assets, Carrying Amount	24,719	16,774
Financial Assets, Fair Value Measurement	24,719	16,774
Loans1 [Member]
Financial assets:
Financial Assets, Carrying Amount	2,086,197	2,024,693
Financial Assets, Fair Value Measurement	2,095,657	2,022,889
Loans Acquired, Not Covered By FDIC Loss Share [Member]
Financial assets:
Financial Assets, Carrying Amount	2,418,440	575,980
Financial Assets, Fair Value Measurement	2,429,407	560,651
Loans Acquired, Covered by FDIC Loss Share [Member]
Financial assets:
Financial Assets, Carrying Amount	102,468	106,933
Financial Assets, Fair Value Measurement	102,933	105,789
FDIC Indemnification Asset [Member]
Financial assets:
Financial Assets, Carrying Amount	15,965	22,663
Financial Assets, Fair Value Measurement	$ 15,965	$ 22,663