Loans And Allowance For Credit Losses (Summary Of ALLL And Outstanding Loan Balances According To The Company's Impairment Method) (Details) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for loan losses: Individually evaluated for impairment	$ (11)	$ (9)
Allowance for loan losses: Collectively evaluated for impairment	484	486
Allowance for loan losses: Total	495	495	$ 518
Loans and Leases Receivable, Gross	48,709	46,714
Commercial [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for loan losses: Individually evaluated for impairment	(8)	(6)
Allowance for loan losses: Collectively evaluated for impairment	333	325
Allowance for loan losses: Total	341	331	371
Outstanding loan balances: Individually evaluated for impairment		164
Outstanding loan balances: Collectively evaluated for impairment		23,998
Commercial Real Estate [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for loan losses: Individually evaluated for impairment		(1)
Allowance for loan losses: Collectively evaluated for impairment		109
Outstanding loan balances: Individually evaluated for impairment		55
Outstanding loan balances: Collectively evaluated for impairment		11,070
Loans and Leases Receivable, Gross	11,555	11,125
Commercial Real Estate [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for loan losses: Individually evaluated for impairment	(1)
Allowance for loan losses: Collectively evaluated for impairment	100
Allowance for loan losses: Total	101	110	103
Loans and Leases Receivable, Gross	2,211	2,186
Consumer Portfolio Segment [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for loan losses: Individually evaluated for impairment	(2)	(2)
Allowance for loan losses: Collectively evaluated for impairment	51	52
Allowance for loan losses: Total	53	54	$ 44
Outstanding loan balances: Individually evaluated for impairment		72
Outstanding loan balances: Collectively evaluated for impairment		11,355
Loans and Leases Receivable, Gross	155	180
Outstanding Loan Balances [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Outstanding loan balances: Individually evaluated for impairment	256	291
Outstanding loan balances: Collectively evaluated for impairment	48,453	46,423
Loans and Leases Receivable, Gross	48,709	46,714
Outstanding Loan Balances [Member] \| Commercial [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Outstanding loan balances: Individually evaluated for impairment	168
Outstanding loan balances: Collectively evaluated for impairment	25,220
Loans and Leases Receivable, Gross	25,388	24,162
Outstanding Loan Balances [Member] \| Commercial Real Estate [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Outstanding loan balances: Individually evaluated for impairment	30
Outstanding loan balances: Collectively evaluated for impairment	11,525
Loans and Leases Receivable, Gross	11,555	11,125
Outstanding Loan Balances [Member] \| Consumer Portfolio Segment [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Outstanding loan balances: Individually evaluated for impairment	58
Outstanding loan balances: Collectively evaluated for impairment	11,708
Loans and Leases Receivable, Gross	$ 11,766	$ 11,427

The valuation allowance for financing receivables that are expected to be uncollectible that were collectively evaluated for impairment.

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Amount of valuation allowance for financing receivables that are expected to be uncollectible that were individually evaluated for impairment.

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The balance of financing receivables that were collectively evaluated for impairment.

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The balance of financing receivables that were individually evaluated for impairment.

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Amount of allowance to cover probable credit losses on loans and leases. Includes carryover of or adjustments to the allowance for loan losses in connection with business combinations. Excludes allowance for loans and leases covered under loss sharing agreements.

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Amount before allowance of loans and leases held in portfolio, including but not limited to, commercial and consumer loans. Includes deferred interest and fees, undisbursed portion of loan balance, unamortized costs and premiums and discounts from face amounts. Excludes loans and leases covered under loss sharing agreements.

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