Loans And Allowance For Credit Losses (Summary Of Outstanding Loan Balances (Accruing And Nonaccruing) Categorized By Credit Quality Indicators) (Details) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2017	Dec. 31, 2016
Financing Receivable, Allowance for Credit Losses [Line Items]
Current Fiscal Year End Date	--12-31
Commercial and industrial	$ 14,003	$ 13,452
Leasing	364	423
Commercial Lending Loans - Owner Occupied	7,288	6,962
Loans and Leases Receivable, Gross, Commercial, Governments	1,271	778
Construction and land development	2,021	2,019
Term	9,103	9,322
Loans Receivable, Gross, Commercial, Real Estate	11,124	11,341
Loans and Leases Receivable, Gross, Consumer, Home Equity	2,777	2,645
1-4 family residential	6,662	5,891
Loans and Leases Receivable, Gross, Consumer, Construction	597	486
Loans and Leases Receivable, Gross, Consumer, Revolving, Credit Card	509	481
Loans and Leases Receivable, Gross, Consumer, Other	185	190
Loans and Leases Receivable, Gross	44,780	42,649
Commercial [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Commercial and industrial	14,003	13,452
Leasing	364	423
Commercial Lending Loans - Owner Occupied	7,288	6,962
Loans and Leases Receivable, Gross, Commercial, Governments	1,271	778
Loans and Leases Receivable, before Fees, Gross	22,926	21,615
Construction And Land Development [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Construction and land development	2,021
Commercial Real Estate [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Construction and land development		2,019
Term	9,103	9,322
Loans Receivable, Gross, Commercial, Real Estate	11,124	11,341
Loans and Leases Receivable, Gross	2,021	2,019
Consumer [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans and Leases Receivable, Gross, Consumer, Home Equity	2,777	2,645
1-4 family residential	6,662	5,891
Loans and Leases Receivable, Gross, Consumer, Construction	597	486
Loans and Leases Receivable, Gross, Consumer, Revolving, Credit Card	509	481
Loans and Leases Receivable, Gross, Consumer, Other	185	190
Loans and Leases Receivable, Gross	185	190
Consumer Loan [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans and Leases Receivable, before Fees, Gross	10,730	9,693
Loans and Leases Receivable, Gross	10,730	9,693
Pass [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans and Leases Receivable, Gross	42,987	40,564
Pass [Member] \| Commercial [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Commercial and industrial	13,001	12,185
Leasing	342	387
Commercial Lending Loans - Owner Occupied	6,920	6,560
Loans and Leases Receivable, Gross, Commercial, Governments	1,257	765
Loans and Leases Receivable, before Fees, Gross	21,520	19,897
Pass [Member] \| Construction And Land Development [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Construction and land development	2,002
Pass [Member] \| Commercial Real Estate [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Construction and land development		1,942
Term	8,816	9,096
Loans Receivable, Gross, Commercial, Real Estate	10,818	11,038
Pass [Member] \| Consumer [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans and Leases Receivable, Gross, Consumer, Home Equity	2,759	2,629
1-4 family residential	6,602	5,851
Loans and Leases Receivable, Gross, Consumer, Construction	596	482
Loans and Leases Receivable, Gross, Consumer, Revolving, Credit Card	507	478
Loans and Leases Receivable, Gross, Consumer, Other	185	189
Pass [Member] \| Consumer Loan [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans and Leases Receivable, before Fees, Gross	10,649	9,629
Special Mention [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans and Leases Receivable, Gross	660	508
Special Mention [Member] \| Commercial [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Commercial and industrial	395	266
Leasing	6	5
Commercial Lending Loans - Owner Occupied	93	96
Loans and Leases Receivable, Gross, Commercial, Governments	13	7
Loans and Leases Receivable, before Fees, Gross	507	374
Special Mention [Member] \| Construction And Land Development [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Construction and land development	15
Special Mention [Member] \| Commercial Real Estate [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Construction and land development		52
Term	138	82
Loans Receivable, Gross, Commercial, Real Estate	153	134
Special Mention [Member] \| Consumer [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
Loans and Leases Receivable, Gross, Consumer, Revolving, Credit Card	0	0
Loans and Leases Receivable, Gross, Consumer, Other	0	0
Special Mention [Member] \| Consumer Loan [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans and Leases Receivable, before Fees, Gross	0	0
Sub-Standard [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans and Leases Receivable, Gross	1,132	1,573
Sub-Standard [Member] \| Commercial [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Commercial and industrial	606	998
Leasing	16	30
Commercial Lending Loans - Owner Occupied	275	306
Loans and Leases Receivable, Gross, Commercial, Governments	1	6
Loans and Leases Receivable, before Fees, Gross	898	1,340
Sub-Standard [Member] \| Construction And Land Development [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Construction and land development	4
Sub-Standard [Member] \| Commercial Real Estate [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Construction and land development		25
Term	149	144
Loans Receivable, Gross, Commercial, Real Estate	153	169
Sub-Standard [Member] \| Consumer [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans and Leases Receivable, Gross, Consumer, Home Equity	18	16
1-4 family residential	60	40
Loans and Leases Receivable, Gross, Consumer, Construction	1	4
Loans and Leases Receivable, Gross, Consumer, Revolving, Credit Card	2	3
Loans and Leases Receivable, Gross, Consumer, Other	0	1
Sub-Standard [Member] \| Consumer Loan [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans and Leases Receivable, before Fees, Gross	81	64
Doubtful [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans and Leases Receivable, Gross	1	4
Doubtful [Member] \| Commercial [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Commercial and industrial	1	3
Leasing	0	1
Commercial Lending Loans - Owner Occupied	0	0
Loans and Leases Receivable, Gross, Commercial, Governments	0	0
Loans and Leases Receivable, before Fees, Gross	1	4
Doubtful [Member] \| Construction And Land Development [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Construction and land development	0
Doubtful [Member] \| Commercial Real Estate [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Construction and land development		0
Term	0	0
Loans Receivable, Gross, Commercial, Real Estate	0	0
Doubtful [Member] \| Consumer [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
Loans and Leases Receivable, Gross, Consumer, Revolving, Credit Card	0	0
Loans and Leases Receivable, Gross, Consumer, Other	0	0
Doubtful [Member] \| Consumer Loan [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans and Leases Receivable, before Fees, Gross	0	0
Total Allowance [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans and Leases Receivable, Gross	518	567
Total Allowance [Member] \| Commercial [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans and Leases Receivable, before Fees, Gross	371	420
Total Allowance [Member] \| Commercial Real Estate [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans Receivable, Gross, Commercial, Real Estate	103	116
Total Allowance [Member] \| Consumer Loan [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans and Leases Receivable, before Fees, Gross	$ 44	$ 31

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Amount before allowance of commercial leases and leveraged lease transactions where the entity is long-term creditor. Includes deferred interest and fees, undisbursed portion of loan balance, unamortized costs and premiums and discounts from face amounts. Excludes leases covered under loss sharing agreements.

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