Allowance for Credit Losses on Loans and Leases - Schedule of Activity in the Allowance for Loan and Lease Losses (Details) - USD ($) $ in Millions	9 Months Ended
Sep. 30, 2023	Sep. 30, 2022
Financing Receivable, Excluding Accrued Interest, Allowance for Credit Loss [Roll Forward]
Balance, beginning of period	$ 393	$ 199
Adjustment for Purchased PCD Loans	13	0
Charge-offs	(34)	(5)
Recoveries	11	10
Provision for (recovery of) credit losses on loans and leases	236	14
Balance, end of period	619	218
Unfunded Loan Commitment
Financing Receivable, Excluding Accrued Interest, Allowance for Credit Loss [Roll Forward]
Balance, beginning of period	23
Balance, end of period	48
Mortgage
Financing Receivable, Excluding Accrued Interest, Allowance for Credit Loss [Roll Forward]
Balance, beginning of period	290	178
Adjustment for Purchased PCD Loans	0	0
Charge-offs	(19)	(5)
Recoveries	0	4
Provision for (recovery of) credit losses on loans and leases	108	31
Balance, end of period	379	208
Other
Financing Receivable, Excluding Accrued Interest, Allowance for Credit Loss [Roll Forward]
Balance, beginning of period	103	21
Adjustment for Purchased PCD Loans	13	0
Charge-offs	(15)	0
Recoveries	11	6
Provision for (recovery of) credit losses on loans and leases	128	(17)
Balance, end of period	$ 240	$ 10

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

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

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

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 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 6
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479319/326-20-50-6

Reference 2: 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 credit loss expense (reversal of expense) on financing receivable. 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 (b)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479319/326-20-50-13

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- Definition

Amount, excluding accrued interest, of allowance for credit loss at acquisition date of financing receivable purchased with credit deterioration. 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 19
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479319/326-20-50-19

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 13
-Subparagraph (c)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479319/326-20-50-13

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