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	Dec. 31, 2011	Dec. 31, 2010
Financial Assets
Cash and due from banks	$ 153,747	$ 144,909	$ 117,888	$ 87,347
Securities held-to-maturity		773,768
Securities held-to-maturity		823,906
Securities available-for-sale	1,586,668	1,291,480
Trading securities	4,936	4,703
Investment in Federal Home Loan Bank stock	25,000	41,272
Financial Liabilities
Deposits	7,981,305	7,383,225
Securities sold under agreement to repurchase	800,000	1,250,000
Advances from Federal Home Loan Bank	521,200	146,200
Long-term debt	121,136	171,136
Carrying Amount [Member]
Financial Assets
Cash and due from banks	153,747	144,909
Short-term investments	516,938	411,983
Short-term investments	516,938	411,983
Securities held-to-maturity		773,768
Securities available-for-sale	1,586,668	1,291,480
Trading securities	4,936	4,703
Loans, net	7,897,187	7,235,587
Investment in Federal Home Loan Bank stock	25,000	41,272
Warrants	30	104
Option contracts	200	105
Foreign exchange contracts	267,644	188,145
Financial Liabilities
Deposits	7,981,305	7,383,225
Securities sold under agreement to repurchase	800,000	1,250,000
Advances from Federal Home Loan Bank	521,200	146,200
Other borrowings	19,062	18,713
Long-term debt	121,136	171,136
Option contracts		104
Foreign exchange contracts	236,350	133,669
Off-Balance Sheet Financial Instruments
Commitments to extend credit	1,858,669	1,740,463
Standby letters of credit	45,058	44,672
Other letters of credit	54,098	71,073
Bill of lading guarantees	80	77
Fair Value [Member]
Financial Assets
Cash and due from banks	153,747	144,909
Short-term investments	516,938	411,983
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
Option contracts	0
Foreign exchange contracts	6,182	2,924
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
Option contracts		2
Foreign exchange contracts	6,140	1,586
Off-Balance Sheet Financial Instruments
Commitments to extend credit	(2,187)	(1,875)
Standby letters of credit	(205)	(204)
Other letters of credit	(34)	(34)
Bill of lading guarantees		$ 0