Credit Quality And Allowance For Credit Losses (Changes In The Allowance For Loan Losses And Related Loan Amounts) (Details) - USD ($) $ in Millions	3 Months Ended
Mar. 31, 2025	Mar. 31, 2024	Dec. 31, 2024	Dec. 31, 2023
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Financing Receivable, Allowance for Credit Loss, Excluding Accrued Interest	$ 683		$ 690
Financing Receivable, Allowance for Credit Loss, Excluding Accrued Interest, Current			725	$ 728
Provision for credit losses	20	$ 14
Financing receivable, allowance for credit loss, excluding accrued interest, end of period	$ 719	$ 728
As a percentage of total loans	1.44%	1.43%
Financing Receivable
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Financing Receivable, Allowance for Credit Loss, Excluding Accrued Interest	$ 683	$ 691	690	688
Financing Receivable, Excluding Accrued Interest, Allowance for Credit Loss, Writeoff	32	21
Financing Receivable, Excluding Accrued Interest, Allowance for Credit Loss, Recovery	6	7
Financing Receivable, Excluding Accrued Interest, Allowance for Credit Loss, Writeoff (Recovery)	26	14
Provision for credit losses	$ 19	$ 17
As a percentage of total loans	1.37%	1.36%
Unused Commitments to Extend Credit
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Financing Receivable, Allowance for Credit Loss, Excluding Accrued Interest	$ 36	$ 37	35	40
Provision for credit losses	1	(3)
Business loans:
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Financing Receivable, Allowance for Credit Loss, Excluding Accrued Interest	659	654	653	651
Provision for credit losses	$ 31	$ 17
As a percentage of total loans	1.44%	1.40%
Business loans: \| Financing Receivable
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Financing Receivable, Allowance for Credit Loss, Excluding Accrued Interest	$ 634	$ 626	625	620
Financing Receivable, Excluding Accrued Interest, Allowance for Credit Loss, Writeoff	31	20
Financing Receivable, Excluding Accrued Interest, Allowance for Credit Loss, Recovery	6	6
Financing Receivable, Excluding Accrued Interest, Allowance for Credit Loss, Writeoff (Recovery)	25	14
Provision for credit losses	$ 34	$ 20
As a percentage of total loans	1.38%	1.34%
Business loans: \| Unused Commitments to Extend Credit
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Financing Receivable, Allowance for Credit Loss, Excluding Accrued Interest	$ 25	$ 28	28	31
Provision for credit losses	(3)	(3)
Retail loans:
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Financing Receivable, Allowance for Credit Loss, Excluding Accrued Interest	60	74	72	77
Provision for credit losses	$ (11)	$ (3)
As a percentage of total loans	1.46%	1.82%
Retail loans: \| Financing Receivable
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Financing Receivable, Allowance for Credit Loss, Excluding Accrued Interest	$ 49	$ 65	65	68
Financing Receivable, Excluding Accrued Interest, Allowance for Credit Loss, Writeoff	1	1
Financing Receivable, Excluding Accrued Interest, Allowance for Credit Loss, Recovery	0	1
Financing Receivable, Excluding Accrued Interest, Allowance for Credit Loss, Writeoff (Recovery)	1	0
Provision for credit losses	$ (15)	$ (3)
As a percentage of total loans	1.19%	1.59%
Retail loans: \| Unused Commitments to Extend Credit
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Financing Receivable, Allowance for Credit Loss, Excluding Accrued Interest	$ 11	$ 9	$ 7	$ 9
Provision for credit losses	$ 4	$ 0

Financing receivable, allowance for credit loss, excluding accrued interest, beginning of period

No definition available.

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- Definition

Financing receivable, allowance for credit loss, excluding accrued interest, end of period

+ References

No definition available.

+ Details

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- Definition

The ratio of Allowance for Credit Losses to All Loans.

+ References

No definition available.

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- Definition

Amount excluding accrued interest, of allowance for credit loss on financing receivable. Excludes net investment in lease.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 45
-Paragraph 1
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479344/326-20-45-1

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- Definition

A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

+ References

No definition available.

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- Definition

Amount, excluding accrued interest, of increase in allowance for credit loss on financing receivable from recovery. Excludes net investment in lease.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 13
-Subparagraph (e)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479319/326-20-50-13

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- Definition

Amount, excluding accrued interest, of decrease in allowance for credit loss on financing receivable from writeoff. Excludes net investment in lease.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 13
-Subparagraph (d)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479319/326-20-50-13

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- Definition

Amount, excluding accrued interest, of decrease (increase) in allowance for credit loss on financing receivable from writeoff (recovery). Excludes net investment in lease.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 13
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479319/326-20-50-13

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- Definition

Amount of expense related loan transactions, lease transactions, credit loss from transactions other than loan and lease transactions, and other loss based on assessment of uncollectability from the counterparty to reduce the account to their net realizable value.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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-Section 45
-Paragraph 28
-Subparagraph (a)
-SubTopic 10
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