Note 12 - Fair Value of Financial Instruments (Detail) - Fair Value of Financial Instruments (USD $)							6 Months Ended	12 Months Ended
	Jun. 30, 2012	Dec. 31, 2011	Jun. 30, 2011	Dec. 31, 2010	Jun. 30, 2012 Carrying Amount [Member]	Dec. 31, 2011 Carrying Amount [Member]	Jun. 30, 2012 Fair Value [Member]	Dec. 31, 2011 Fair Value [Member]
Financial Assets
Cash and due from banks	$ 134,744,000	$ 117,888,000	$ 128,584,000	$ 87,347,000	$ 134,744,000	$ 117,888,000
Cash and due from banks							134,744,000	117,888,000
Short-term investments					513,636,000	294,956,000	513,636,000	294,956,000
Short-term investments					513,636,000	294,956,000	513,636,000	294,956,000
Securities purchased under agreements to resell	10,000,000				10,000,000	0
Securities purchased under agreements to resell							10,000,000	0
Securities held-to-maturity	1,019,977,000	1,153,504,000			1,019,977,000	1,153,504,000
Securities held-to-maturity							1,073,077,000	1,203,977,000
Securities available-for-sale	1,166,783,000	1,294,478,000			1,166,783,000	1,294,478,000
Securities available-for-sale	1,166,783,000						1,166,783,000	1,294,478,000
Trading securities					104,465,000	4,542,000
Trading securities							104,465,000	4,542,000
Loans held-for-sale	500,000	760,000			500,000	760,000
Loans held-for-sale							500,000	760,000
Loans, net					6,842,554,000	6,844,483,000
Loans, net							6,799,987,000	6,825,571,000
Investment in Federal Home Loan Bank stock	47,966,000	52,989,000			47,966,000	52,989,000
Investment in Federal Home Loan Bank stock							47,966,000	52,989,000
Warrants					169,000	218,000
Warrants							169,000	218,000
Option contracts					862,000	3,026,000
Option contracts							4,000	34,000
Foreign exchange contracts					204,813,000	238,581,000
Foreign exchange contracts							1,910,000	2,151,000
Financial Liabilities
Deposits	7,384,233,000	7,229,131,000			7,384,233,000	7,229,131,000
Deposits							7,392,033,000	7,240,857,000
Securities sold under agreements to repurchase	1,400,000,000	1,400,000,000			1,400,000,000	1,400,000,000
Securities sold under agreements to repurchase							1,533,780,000	1,547,900,000
Advances from Federal Home Loan Bank	21,200,000	225,000,000			21,200,000	225,000,000
Advances from Federal Home Loan Bank							21,597,000	227,825,000
Other borrowings					18,834,000	19,800,000
Other borrowings							18,834,000	19,801,000
Long-term debt	171,136,000	171,136,000			171,136,000	171,136,000
Long-term debt							96,681,000	98,676,000
Option contracts					205,000	1,282,000
Option contracts							1,000	5,000
Interest rate swaps					300,000,000	300,000,000
Interest rate swaps	742,000	2,600,000					742,000	2,634,000
Foreign exchange contracts					154,267,000	128,215,000
Foreign exchange contracts							1,089,000	486,000
Off-Balance Sheet Financial Instruments
Commitments to extend credit					1,718,710,000	1,626,523,000
Commitments to extend credit							(1,587,000)	(1,253,000)
Standby letters of credit					54,110,000	62,076,000
Standby letters of credit							(188,000)	(367,000)
Other letters of credit					77,252,000	64,233,000
Other letters of credit							(37,000)	(38,000)
Bill of lading guarantees					143,000	187,000
Bill of lading guarantees								$ 0