Fair Value Of Financial Instruments (Estimated Fair Value Of Financial Instruments) (Details) (USD $)					12 Months Ended
	Dec. 31, 2011	Mar. 31, 2011	Dec. 31, 2010	Dec. 31, 2009	Dec. 31, 2011 Financial Assets [Member] Carrying Amount [Member]	Dec. 31, 2010 Financial Assets [Member] Carrying Amount [Member]	Dec. 31, 2011 Financial Assets [Member] Fair Value [Member]	Dec. 31, 2010 Financial Assets [Member] Fair Value [Member]	Dec. 31, 2011 Financial Assets [Member] Notional Amount [Member]	Dec. 31, 2010 Financial Assets [Member] Notional Amount [Member]	Dec. 31, 2011 Financial Liabilities [Member] Carrying Amount [Member]	Dec. 31, 2010 Financial Liabilities [Member] Carrying Amount [Member]	Dec. 31, 2011 Financial Liabilities [Member] Fair Value [Member]	Dec. 31, 2010 Financial Liabilities [Member] Fair Value [Member]	Dec. 31, 2011 Financial Liabilities [Member] Notional Amount [Member]	Dec. 31, 2010 Financial Liabilities [Member] Notional Amount [Member]	Dec. 31, 2011 Off-Balance Sheet Financial Instruments [Member]	Dec. 31, 2010 Off-Balance Sheet Financial Instruments [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and due from banks					$ 117,888,000	$ 87,347,000	$ 117,888,000	$ 87,347,000
Short-term investments					294,956,000	206,321,000	294,956,000	206,321,000
Securities purchased under agreements to resell			110,000,000			110,000,000		110,000,000
Securities held-to-maturity	1,153,504,000		840,102,000		1,153,504,000	840,102,000	1,203,977,000	837,359,000
Securities available-for-sale	1,294,478,000		2,003,567,000		1,294,478,000	2,003,567,000	1,294,478,000	2,003,567,000
Trading securities					4,542,000	3,818,000	4,542,000	3,818,000
Loans held-for-sale	760,000		2,873,000		760,000	2,873,000	760,000	2,873,000
Loans, net					6,844,483,000	6,615,769,000	6,825,571,000	6,596,501,000
Investment in Federal Home Loan Bank stock					52,989,000	63,873,000	52,989,000	63,873,000
Warrants					218,000	40,000	218,000	40,000
Option contracts							34,000	106,000	3,026,000	29,336,000
Foreign exchange contracts							2,151,000	4,629,000	238,581,000	112,665,000
Deposits											7,229,131,000	6,991,846,000	7,240,857,000	7,006,913,000
Securities sold under agreements to repurchase	1,400,000,000	1,500,000,000	1,561,000,000	1,600,000,000							1,400,000,000	1,561,000,000	1,547,900,000	1,704,585,000
Advances from Federal Home Loan Bank											225,000,000	550,000,000	227,825,000	580,054,000
Other borrowings	880,000		8,500,000								19,800,000	27,576,000	19,801,000	27,585,000
Long-term debt											171,136,000	171,136,000	98,676,000	114,557,000
Option contracts													5,000	72,000	1,282,000	72,000
Interest rate swaps	2,600,000		6,500,000										2,634,000	6,508,000	300,000,000	300,000,000
Foreign exchange contracts													486,000	1,873,000	128,215,000	68,355,000
Commitments to extend credit, Notional Amount																	1,626,523,000	1,360,266,000
Commitments to extend credit, Fair Value																	(1,253,000)	(603,000)
Standby letters of credit, Notional Amount																	62,076,000	59,876,000
Standby letters of credit, Fair Value																	(367,000)	(282,000)
Other letters of credit, Notional Amount																	64,233,000	62,722,000
Other letters of credit, Fair Value																	(38,000)	(38,000)
Bill of lading guarantees, Notional Amount																	187,000	245,000
Bill of lading guarantees, Fair Value																		$ (1,000)