Loans And Allowance For Credit Losses (Summary Of Nonaccrual Loans) (Details) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2012	Dec. 31, 2011
Financing Receivable, Allowance for Credit Losses [Line Items]
Total	$ 793,460	$ 891,659
Commercial and industrial	10,382,676	10,334,858
Home equity credit line	2,180,857	2,187,428
1-4 family residential	4,018,858	3,921,216
Construction and other consumer real estate	327,867	305,873
Bankcard and other revolving plans	284,112	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	21,980	24,267
Commercial [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total	374,049	367,217
Commercial and industrial	10,382,676	10,334,858
Commercial [Member] | Commercial And Industrial [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Commercial and industrial	133,241	126,468
Commercial [Member] | Leasing [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total	1,259	1,546
Commercial [Member] | Owner Occupied [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total	239,549	239,203
Commercial Real Estate [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total	297,823	376,002
Commercial Real Estate [Member] | Construction And Land Development [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total	115,411	219,837
Commercial Real Estate [Member] | Term [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total	182,412	156,165
Consumer [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total	99,608	124,173
Home equity credit line	2,180,857	2,187,428
1-4 family residential	4,018,858	3,921,216
Construction and other consumer real estate	327,867	305,873
Bankcard and other revolving plans	284,112	291,018
Consumer [Member] | Home Equity Credit Line [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Home equity credit line	13,741	18,376
Consumer [Member] | 1-4 Family Residential [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
1-4 family residential	74,935	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	7,731	12,096
Consumer [Member] | Bankcard And Other Revolving Plans [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Bankcard and other revolving plans	1,256	346
Consumer [Member] | Other [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total	$ 1,945	$ 2,498