Loans And Allowance For Credit Losses (Summary Of Nonaccrual Loans) (Details) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2012	Dec. 31, 2011
Financing Receivable, Allowance for Credit Losses [Line Items]
Total	$ 872,136	$ 891,659
Commercial and industrial	10,157,262	10,334,858
Municipal	440,747	441,241
Home equity credit line	2,167,099	2,187,428
1-4 family residential	3,874,533	3,921,216
Construction and other consumer real estate	316,257	305,873
Bankcard and other revolving plans	273,591	291,018
Loans Held For Sale [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Commercial and industrial	30	18,216
FDIC-Supported Loans [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total	22,623	24,267
Commercial [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total	396,028	367,217
Commercial and industrial	10,157,262	10,334,858
Municipal	440,747	441,241
Commercial [Member] | Commercial And Industrial [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Commercial and industrial	149,337	126,468
Commercial [Member] | Leasing [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total	1,343	1,546
Commercial [Member] | Owner Occupied [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total	245,348	239,203
Commercial Real Estate [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total	337,912	376,002
Commercial Real Estate [Member] | Construction And Land Development [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total	147,640	219,837
Commercial Real Estate [Member] | Term [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total	190,272	156,165
Consumer [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total	115,573	124,173
Home equity credit line	2,167,099	2,187,428
1-4 family residential	3,874,533	3,921,216
Construction and other consumer real estate	316,257	305,873
Bankcard and other revolving plans	273,591	291,018
Consumer [Member] | Home Equity Credit Line [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Home equity credit line	17,425	18,376
Consumer [Member] | 1-4 Family Residential [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
1-4 family residential	86,910	90,857
Consumer [Member] | Construction And Other Consumer Real Estate [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Construction and other consumer real estate	8,060	12,096
Consumer [Member] | Bankcard And Other Revolving Plans [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Bankcard and other revolving plans	537	346
Consumer [Member] | Other [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total	$ 2,641	$ 2,498