Allowance for Credit Losses - Gross Charge-Offs by Year of Origination - Prior Year (Details) - USD ($) $ in Millions	3 Months Ended
Mar. 31, 2026	Mar. 31, 2025
Accounts, Notes, Loans and Financing Receivable [Line Items]
2025	$ 2	$ 2
2024	0	0
2023	8	0
2022	9	5
2021	4	16
Prior to 2021	15	15
Revolving Loans	7	3
Total Charge-offs	45	41
Commercial \| Commercial, Financial, and Industrial
Accounts, Notes, Loans and Financing Receivable [Line Items]
2025	0	0
2024	0	0
2023	8	0
2022	8	5
2021	3	16
Prior to 2021	12	12
Revolving Loans	5	1
Total Charge-offs	36	34
Commercial \| CRE
Accounts, Notes, Loans and Financing Receivable [Line Items]
2025	0	0
2024	0	0
2023	0	0
2022	0	0
2021	1	0
Prior to 2021	3	3
Revolving Loans	0	0
Total Charge-offs	4	3
Consumer \| Consumer Real Estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
2025	0	0
2024	0	0
2023	0	0
2022	1	0
2021	0	0
Prior to 2021	0	0
Revolving Loans	0	0
Total Charge-offs	1	0
Consumer \| Credit Card and Other
Accounts, Notes, Loans and Financing Receivable [Line Items]
2025	2	2
2024	0	0
2023	0	0
2022	0	0
2021	0	0
Prior to 2021	0	0
Revolving Loans	2	2
Total Charge-offs	$ 4	$ 4

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 310
-SubTopic 20
-Name Accounting Standards Codification
-Section 40
-Paragraph 7
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481628/310-20-40-7

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 310
-SubTopic 10
-Name Accounting Standards Codification
-Section 45
-Paragraph 2
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481990/310-10-45-2

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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

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 326
-SubTopic 20
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-Section 50
-Paragraph 6
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479319/326-20-50-6

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Amount, excluding accrued interest, of writeoff of financing receivable originated more than five years before current fiscal year. Excludes net investment in lease.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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-SubTopic 20
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-URI https://asc.fasb.org/1943274/2147479319/326-20-50-6

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Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 326
-SubTopic 20
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-URI https://asc.fasb.org/1943274/2147479319/326-20-50-6A

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Amount, excluding accrued interest, of writeoff of financing receivable originated three years before current fiscal year. Excludes net investment in lease.

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