Loans And Allowance For Credit Losses (Summary Of Outstanding Loan Balances (Accruing And Nonaccruing) Categorized By Credit Quality Indicators) (Details) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2015	Dec. 31, 2014
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans held for sale	$ 128,946	$ 132,504
Commercial and industrial	13,264,092	13,162,955
Leasing	407,137	408,974
Owner occupied	7,309,639	7,351,548
Municipal	555,122	520,887
Total commercial	21,535,990	21,444,364
Construction and land development	2,044,641	1,986,408
Term	8,088,430	8,126,600
Total commercial real estate	10,133,071	10,113,008
Loans and Leases Receivable, Gross, Consumer, Home Equity	2,314,806	2,321,150
1-4 family residential	5,212,963	5,200,882
Loans and Leases Receivable, Gross, Consumer, Construction	373,335	370,542
Bankcard and other revolving plans	406,723	401,352
Other	203,226	212,360
Total consumer	8,511,053	8,506,286
Total loans	40,180,114	40,063,658
Consumer Portfolio Segment [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans and Leases Receivable, Gross, Consumer, Home Equity	2,314,806	2,321,150
1-4 family residential	5,212,963	5,200,882
Loans and Leases Receivable, Gross, Consumer, Construction	373,335	370,542
Bankcard and other revolving plans	406,723	401,352
Other	203,226	212,360
Total consumer	8,511,053	8,506,286
Total loans	8,511,053	8,506,286
Commercial Real Estate [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Term	8,088,430	8,126,600
Total commercial real estate	10,133,071	10,113,008
Total loans	10,133,071	10,113,008
Commercial Real Estate Construction Financing Receivable [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Construction and land development	2,044,641	1,986,408
Total loans	2,044,641	1,986,408
Commercial [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Commercial and industrial	13,264,092	13,162,955
Leasing	407,137	408,974
Owner occupied	7,309,639	7,351,548
Municipal	555,122	520,887
Total commercial	21,535,990	21,444,364
Total loans	21,535,990	21,444,364
Pass [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans	38,383,629	38,428,158
Pass [Member] | Consumer Portfolio Segment [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans and Leases Receivable, Gross, Consumer, Home Equity	2,298,505	2,304,352
1-4 family residential	5,149,513	5,138,660
Loans and Leases Receivable, Gross, Consumer, Construction	370,817	367,932
Bankcard and other revolving plans	404,826	399,446
Other	202,909	211,811
Total consumer	8,426,570	8,422,201
Pass [Member] | Commercial Real Estate [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Term	7,827,313	7,802,571
Total commercial real estate	9,821,385	9,728,256
Pass [Member] | Commercial Real Estate Construction Financing Receivable [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Construction and land development	1,994,072	1,925,685
Pass [Member] | Commercial [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Commercial and industrial	12,342,163	12,515,846
Leasing	388,843	399,032
Owner occupied	6,851,794	6,844,310
Municipal	552,874	518,513
Total commercial	20,135,674	20,277,701
Special Mention [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans	527,739	488,635
Special Mention [Member] | Consumer Portfolio Segment [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans and Leases Receivable, Gross, Consumer, Home Equity	0	0
1-4 family residential	0	0
Loans and Leases Receivable, Gross, Consumer, Construction	0	0
Bankcard and other revolving plans	0	0
Other	0	0
Total consumer	0	0
Special Mention [Member] | Commercial Real Estate [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Term	68,890	96,347
Total commercial real estate	77,405	104,811
Special Mention [Member] | Commercial Real Estate Construction Financing Receivable [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Construction and land development	8,515	8,464
Special Mention [Member] | Commercial [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Commercial and industrial	325,604	209,215
Leasing	11,656	4,868
Owner occupied	111,853	168,423
Municipal	1,221	1,318
Total commercial	450,334	383,824
Total Allowance [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans	620,013	604,663
Total Allowance [Member] | Consumer Portfolio Segment [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total consumer	46,326	47,140
Total Allowance [Member] | Commercial Real Estate [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total commercial real estate	131,615	145,009
Total Allowance [Member] | Commercial [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total commercial	442,072	412,514
Doubtful [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans	13,481	16,250
Doubtful [Member] | Consumer Portfolio Segment [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans and Leases Receivable, Gross, Consumer, Home Equity	0	0
1-4 family residential	0	0
Loans and Leases Receivable, Gross, Consumer, Construction	0	0
Bankcard and other revolving plans	0	0
Other	0	0
Total consumer	0	0
Doubtful [Member] | Commercial Real Estate [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Term	4,428	4,358
Total commercial real estate	4,428	4,358
Doubtful [Member] | Commercial Real Estate Construction Financing Receivable [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Construction and land development	0	0
Doubtful [Member] | Commercial [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Commercial and industrial	9,053	11,892
Leasing	0	0
Owner occupied	0	0
Municipal	0	0
Total commercial	9,053	11,892
Substandard [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans	1,255,265	1,130,615
Substandard [Member] | Consumer Portfolio Segment [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans and Leases Receivable, Gross, Consumer, Home Equity	16,301	16,798
1-4 family residential	63,450	62,222
Loans and Leases Receivable, Gross, Consumer, Construction	2,518	2,610
Bankcard and other revolving plans	1,897	1,906
Other	317	549
Total consumer	84,483	84,085
Substandard [Member] | Commercial Real Estate [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Term	187,799	223,324
Total commercial real estate	229,853	275,583
Substandard [Member] | Commercial Real Estate Construction Financing Receivable [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Construction and land development	42,054	52,259
Substandard [Member] | Commercial [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Commercial and industrial	587,272	426,002
Leasing	6,638	5,074
Owner occupied	345,992	338,815
Municipal	1,027	1,056
Total commercial	$ 940,929	$ 770,947