Note 20 - Fair Value Measurements (Details) - Estimated Fair Values and Related Carrying Amounts of Financial Instruments - USD ($) $ in Thousands	Jun. 30, 2015	Dec. 31, 2014
Financial assets:
Financial Assets, Carrying Amount	$ 7,614,358	$ 4,643,354
Financial Liabilities, Carrying Amount	6,589,253	4,149,035
Cash and Cash Equivalents [Member]
Financial assets:
Financial Assets, Carrying Amount	292,470	335,909
Financial Assets, Fair Value Measurement	292,470	335,909
Interest Bearing Balances Due from Banks - Time [Member]
Financial assets:
Financial Assets, Carrying Amount	24,189
Financial Assets, Fair Value Measurement	24,180
Held-to-Maturity Securities [Member]
Financial assets:
Financial Assets, Carrying Amount	861,596	777,587
Financial Assets, Fair Value Measurement	863,349	780,533
Mortgage Loans Held For Sale [Member]
Financial assets:
Financial Assets, Carrying Amount	48,094	21,265
Financial Assets, Fair Value Measurement	48,094	21,265
Interest Receivable [Member]
Financial assets:
Financial Assets, Carrying Amount	24,129	16,774
Financial Assets, Fair Value Measurement	24,129	16,774
Loans1 [Member]
Financial assets:
Financial Assets, Carrying Amount	2,580,662	2,024,693
Financial Assets, Fair Value Measurement	2,585,022	2,022,889
Loans Acquired, Not Covered By FDIC Loss Share [Member]
Financial assets:
Financial Assets, Carrying Amount	2,108,306	575,980
Financial Assets, Fair Value Measurement	2,111,868	560,651
Loans Acquired, Covered by FDIC Loss Share [Member]
Financial assets:
Financial Assets, Carrying Amount	93,121	106,933
Financial Assets, Fair Value Measurement	93,278	105,789
FDIC Indemnification Asset [Member]
Financial assets:
Financial Assets, Carrying Amount	13,020	22,663
Financial Assets, Fair Value Measurement	13,020	22,663
Non-Interest Bearing Transaction Accounts [Member]
Financial assets:
Financial Liabilities, Carrying Amount	1,141,285	889,260
Financial Liabilities, Fair Value Measurement	1,141,285	889,260
Interest Bearing Transaction Accounts and Savings Deposits [Member]
Financial assets:
Financial Liabilities, Carrying Amount	3,581,049	2,006,271
Financial Liabilities, Fair Value Measurement	3,581,049	2,006,271
Time Deposits [Member]
Financial assets:
Financial Liabilities, Carrying Amount	1,447,688	965,187
Financial Liabilities, Fair Value Measurement	1,443,811	967,900
Federal Funds Purchased and Securities Sold under Agreements to Repurchase [Member]
Financial assets:
Financial Liabilities, Carrying Amount	111,792	110,586
Financial Liabilities, Fair Value Measurement	111,792	110,586
Other Borrowings [Member]
Financial assets:
Financial Liabilities, Carrying Amount	171,321	114,682
Financial Liabilities, Fair Value Measurement	176,279	114,698
Subordinated Debentures [Member]
Financial assets:
Financial Liabilities, Carrying Amount	61,794	20,620
Financial Liabilities, Fair Value Measurement	56,876	16,115
Interest Payable [Member]
Financial assets:
Financial Liabilities, Carrying Amount	2,234	1,147
Financial Liabilities, Fair Value Measurement	2,234	1,147
Fair Value, Inputs, Level 1 [Member] | Cash and Cash Equivalents [Member]
Financial assets:
Financial Assets, Fair Value Measurement	292,470	335,909
Fair Value, Inputs, Level 2 [Member] | Interest Bearing Balances Due from Banks - Time [Member]
Financial assets:
Financial Assets, Fair Value Measurement	24,180
Fair Value, Inputs, Level 2 [Member] | Held-to-Maturity Securities [Member]
Financial assets:
Financial Assets, Fair Value Measurement	863,349	780,533
Fair Value, Inputs, Level 2 [Member] | Interest Receivable [Member]
Financial assets:
Financial Assets, Fair Value Measurement	24,129	16,774
Fair Value, Inputs, Level 2 [Member] | Non-Interest Bearing Transaction Accounts [Member]
Financial assets:
Financial Liabilities, Fair Value Measurement	1,141,285	889,260
Fair Value, Inputs, Level 2 [Member] | Interest Bearing Transaction Accounts and Savings Deposits [Member]
Financial assets:
Financial Liabilities, Fair Value Measurement	3,581,049	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	111,792	110,586
Fair Value, Inputs, Level 2 [Member] | Other Borrowings [Member]
Financial assets:
Financial Liabilities, Fair Value Measurement	176,279	114,698
Fair Value, Inputs, Level 2 [Member] | Subordinated Debentures [Member]
Financial assets:
Financial Liabilities, Fair Value Measurement	56,876	16,115
Fair Value, Inputs, Level 2 [Member] | Interest Payable [Member]
Financial assets:
Financial Liabilities, Fair Value Measurement	2,234	1,147
Fair Value, Inputs, Level 3 [Member] | Mortgage Loans Held For Sale [Member]
Financial assets:
Financial Assets, Fair Value Measurement	48,094	21,265
Fair Value, Inputs, Level 3 [Member] | Loans1 [Member]
Financial assets:
Financial Assets, Fair Value Measurement	2,585,022	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	2,111,868	560,651
Fair Value, Inputs, Level 3 [Member] | Loans Acquired, Covered by FDIC Loss Share [Member]
Financial assets:
Financial Assets, Fair Value Measurement	93,278	105,789
Fair Value, Inputs, Level 3 [Member] | FDIC Indemnification Asset [Member]
Financial assets:
Financial Assets, Fair Value Measurement	13,020	22,663
Fair Value, Inputs, Level 3 [Member] | Time Deposits [Member]
Financial assets:
Financial Liabilities, Fair Value Measurement	$ 1,443,811	$ 967,900