Allowance for Credit Losses - Gross Charge-Offs by Year of Origination (Details) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
Jun. 30, 2025	Jun. 30, 2024	Jun. 30, 2025	Jun. 30, 2024
Allowance for Loan and Lease Losses [Roll Forward]
Year one, current fiscal year charge offs			$ 6	$ 4
Year two, current fiscal year charge offs			3	9
Year three, current fiscal year charge offs			2	12
Year four, current fiscal year charge offs			14	20
Year five, current fiscal year charge offs			21	10
Prior year charge offs			32	34
Revolving loans charge offs			6	6
Total charge offs	$ 43	$ 49	84	95
Commercial: \| Commercial, financial, and industrial
Allowance for Loan and Lease Losses [Roll Forward]
Year one, current fiscal year charge offs			3	0
Year two, current fiscal year charge offs			3	9
Year three, current fiscal year charge offs			1	11
Year four, current fiscal year charge offs			7	20
Year five, current fiscal year charge offs			19	1
Prior year charge offs			26	9
Revolving loans charge offs			3	2
Total charge offs	28	24	62	52
Commercial: \| Commercial Real Estate
Allowance for Loan and Lease Losses [Roll Forward]
Year one, current fiscal year charge offs			0	0
Year two, current fiscal year charge offs			0	0
Year three, current fiscal year charge offs			0	0
Year four, current fiscal year charge offs			5	0
Year five, current fiscal year charge offs			0	9
Prior year charge offs			5	23
Revolving loans charge offs			0	0
Total charge offs	7	19	10	32
Consumer: \| Consumer Real Estate
Allowance for Loan and Lease Losses [Roll Forward]
Year one, current fiscal year charge offs			0	0
Year two, current fiscal year charge offs			0	0
Year three, current fiscal year charge offs			1	0
Year four, current fiscal year charge offs			1	0
Year five, current fiscal year charge offs			0	0
Prior year charge offs			0	1
Revolving loans charge offs			0	0
Total charge offs	2	1	2	1
Consumer: \| Credit Card and Other
Allowance for Loan and Lease Losses [Roll Forward]
Year one, current fiscal year charge offs			3	4
Year two, current fiscal year charge offs			0	0
Year three, current fiscal year charge offs			0	1
Year four, current fiscal year charge offs			1	0
Year five, current fiscal year charge offs			2	0
Prior year charge offs			1	1
Revolving loans charge offs			3	4
Total charge offs	$ 6	$ 5	$ 10	$ 10

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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

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

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- Definition

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
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 6
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479319/326-20-50-6

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- Definition

Amount, excluding accrued interest, of writeoff of revolving financing receivable converted to term loan.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 6A
-Publisher FASB
-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 four years before current fiscal year. Excludes net investment in lease.

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

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

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

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