Note 17 - Fair Value of Financial Instruments (Details) - Fair Value of Financial Instruments (USD $) In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
Financial Assets
Securities held-to-maturity		$ 823,906
Securities available-for-sale	1,586,668	1,291,480
Trading securities	4,936	4,703
Estimate of Fair Value Measurement [Member]
Financial Assets
Cash and due from banks	153,747	144,909
Short-term investments	516,938	411,983
Securities held-to-maturity		823,906
Securities available-for-sale	1,586,668	1,291,480
Trading securities	4,936	4,703
Loans, net	7,760,490	7,169,732
Investment in Federal Home Loan Bank stock	25,000	41,272
Warrants	30	104
Financial Liabilities
Deposits	7,977,639	7,389,015
Securities sold under agreement to repurchase	852,835	1,361,585
Advances from Federal Home Loan Bank	521,560	146,789
Other borrowings	16,107	14,573
Long-term debt	58,970	98,392
Fair Value, Inputs, Level 1 [Member]
Financial Assets
Cash and due from banks	153,747	144,909
Short-term investments	516,938	411,983
Securities available-for-sale	465,917	526,165
Fair Value, Inputs, Level 2 [Member]
Financial Assets
Securities held-to-maturity		823,906
Securities available-for-sale	1,120,751	765,315
Trading securities	4,936	4,703
Investment in Federal Home Loan Bank stock	25,000	41,272
Financial Liabilities
Securities sold under agreement to repurchase	852,835	1,361,585
Advances from Federal Home Loan Bank	521,560	146,789
Long-term debt	58,970	98,392
Fair Value, Inputs, Level 3 [Member]
Financial Assets
Securities available-for-sale		0
Loans, net	7,760,490	7,169,732
Warrants	30	104
Financial Liabilities
Deposits	7,977,639	7,389,015
Other borrowings	$ 16,107	$ 14,573