Note 20 - Fair Value Measurements (Details) - Estimated Fair Values and Related Carrying Amounts of Financial Instruments - USD ($) $ in Thousands	Sep. 30, 2015	Dec. 31, 2014
Financial assets:
Financial Assets, Carrying Amount	$ 7,559,694	$ 4,643,354
Financial Liabilities, Carrying Amount	6,514,253	4,149,035
Cash and Cash Equivalents [Member]
Financial assets:
Financial Assets, Carrying Amount	400,998	335,909
Financial Assets, Fair Value Measurement	400,998	335,909
Interest Bearing Balances Due from Banks - Time [Member]
Financial assets:
Financial Assets, Carrying Amount	16,504
Financial Assets, Fair Value Measurement	16,498
Held-to-Maturity Securities [Member]
Financial assets:
Financial Assets, Carrying Amount	776,294	777,587
Financial Assets, Fair Value Measurement	785,029	780,533
Mortgage Loans Held For Sale [Member]
Financial assets:
Financial Assets, Carrying Amount	15,556	21,265
Financial Assets, Fair Value Measurement	15,556	21,265
Interest Receivable [Member]
Financial assets:
Financial Assets, Carrying Amount	26,873	16,774
Financial Assets, Fair Value Measurement	26,873	16,774
Loans1 [Member]
Financial assets:
Financial Assets, Carrying Amount	2,808,898	2,024,693
Financial Assets, Fair Value Measurement	2,808,148	2,022,889
Loans Acquired, Not Covered By FDIC Loss Share [Member]
Financial assets:
Financial Assets, Carrying Amount	2,013,816	575,980
Financial Assets, Fair Value Measurement	2,007,543	560,651
Loans Acquired, Covered by FDIC Loss Share [Member]
Financial assets:
Financial Assets, Carrying Amount		106,933
Financial Assets, Fair Value Measurement		105,789
FDIC Indemnification Asset [Member]
Financial assets:
Financial Assets, Carrying Amount		22,663
Financial Assets, Fair Value Measurement		22,663
Non-Interest Bearing Transaction Accounts [Member]
Financial assets:
Financial Liabilities, Carrying Amount	1,212,724	889,260
Financial Liabilities, Fair Value Measurement	1,212,724	889,260
Interest Bearing Transaction Accounts and Savings Deposits [Member]
Financial assets:
Financial Liabilities, Carrying Amount	3,521,840	2,006,271
Financial Liabilities, Fair Value Measurement	3,521,840	2,006,271
Time Deposits [Member]
Financial assets:
Financial Liabilities, Carrying Amount	1,355,236	965,187
Financial Liabilities, Fair Value Measurement	1,353,622	967,900
Federal Funds Purchased and Securities Sold under Agreements to Repurchase [Member]
Financial assets:
Financial Liabilities, Carrying Amount	110,437	110,586
Financial Liabilities, Fair Value Measurement	110,437	110,586
Other Borrowings [Member]
Financial assets:
Financial Liabilities, Carrying Amount	173,426	114,682
Financial Liabilities, Fair Value Measurement	178,214	114,698
Subordinated Debentures [Member]
Financial assets:
Financial Liabilities, Carrying Amount	61,906	20,620
Financial Liabilities, Fair Value Measurement	57,202	16,115
Interest Payable [Member]
Financial assets:
Financial Liabilities, Carrying Amount	1,983	1,147
Financial Liabilities, Fair Value Measurement	1,983	1,147
Fair Value, Inputs, Level 1 [Member] | Cash and Cash Equivalents [Member]
Financial assets:
Financial Assets, Fair Value Measurement	400,998	335,909
Fair Value, Inputs, Level 2 [Member] | Interest Bearing Balances Due from Banks - Time [Member]
Financial assets:
Financial Assets, Fair Value Measurement	16,498
Fair Value, Inputs, Level 2 [Member] | Held-to-Maturity Securities [Member]
Financial assets:
Financial Assets, Fair Value Measurement	785,029	780,533
Fair Value, Inputs, Level 2 [Member] | Interest Receivable [Member]
Financial assets:
Financial Assets, Fair Value Measurement	26,873	16,774
Fair Value, Inputs, Level 2 [Member] | Non-Interest Bearing Transaction Accounts [Member]
Financial assets:
Financial Liabilities, Fair Value Measurement	1,212,724	889,260
Fair Value, Inputs, Level 2 [Member] | Interest Bearing Transaction Accounts and Savings Deposits [Member]
Financial assets:
Financial Liabilities, Fair Value Measurement	3,521,840	2,006,271
Fair Value, Inputs, Level 2 [Member] | Federal Funds Purchased and Securities Sold under Agreements to Repurchase [Member]
Financial assets:
Financial Liabilities, Fair Value Measurement	110,437	110,586
Fair Value, Inputs, Level 2 [Member] | Other Borrowings [Member]
Financial assets:
Financial Liabilities, Fair Value Measurement	178,214	114,698
Fair Value, Inputs, Level 2 [Member] | Subordinated Debentures [Member]
Financial assets:
Financial Liabilities, Fair Value Measurement	57,202	16,115
Fair Value, Inputs, Level 2 [Member] | Interest Payable [Member]
Financial assets:
Financial Liabilities, Fair Value Measurement	1,983	1,147
Fair Value, Inputs, Level 3 [Member] | Mortgage Loans Held For Sale [Member]
Financial assets:
Financial Assets, Fair Value Measurement	15,556	21,265
Fair Value, Inputs, Level 3 [Member] | Loans1 [Member]
Financial assets:
Financial Assets, Fair Value Measurement	2,808,148	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	2,007,543	560,651
Fair Value, Inputs, Level 3 [Member] | Loans Acquired, Covered by FDIC Loss Share [Member]
Financial assets:
Financial Assets, Fair Value Measurement		105,789
Fair Value, Inputs, Level 3 [Member] | FDIC Indemnification Asset [Member]
Financial assets:
Financial Assets, Fair Value Measurement		22,663
Fair Value, Inputs, Level 3 [Member] | Time Deposits [Member]
Financial assets:
Financial Liabilities, Fair Value Measurement	$ 1,353,622	$ 967,900