Loans And Allowance For Credit Losses (Summary Of Nonaccrual Loans) (Details) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2012	Dec. 31, 2011
Financing Receivable, Allowance for Credit Losses [Line Items]
Total	$ 719,377	$ 891,659
Commercial and industrial	10,748,266	10,334,858
Home equity credit line	2,175,338	2,187,428
1-4 family residential	4,181,002	3,921,216
Construction and other consumer real estate	320,087	305,873
Bankcard and other revolving plans	294,827	291,018
Loans Held For Sale [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Commercial and industrial	29	18,216
FDIC-Supported Loans [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total	19,454	24,267
Commercial [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total	333,915	367,217
Commercial and industrial	10,748,266	10,334,858
Commercial [Member] | Commercial And Industrial [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Commercial and industrial	103,206	126,468
Commercial [Member] | Leasing [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total	1,393	1,546
Commercial [Member] | Owner Occupied [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total	223,419	239,203
Commercial [Member] | Municipal [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total	5,897	0
Commercial Real Estate [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total	279,996	376,002
Commercial Real Estate [Member] | Construction And Land Development [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total	124,855	219,837
Commercial Real Estate [Member] | Term [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total	155,141	156,165
Consumer [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total	86,012	124,173
Home equity credit line	2,175,338	2,187,428
1-4 family residential	4,181,002	3,921,216
Construction and other consumer real estate	320,087	305,873
Bankcard and other revolving plans	294,827	291,018
Consumer [Member] | Home Equity Credit Line [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Home equity credit line	11,867	18,376
Consumer [Member] | 1-4 Family Residential [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
1-4 family residential	65,736	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	6,110	12,096
Consumer [Member] | Bankcard And Other Revolving Plans [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Bankcard and other revolving plans	871	346
Consumer [Member] | Other [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total	$ 1,428	$ 2,498