Loans and Allowance for Loan Losses - Schedule of Rollforward of Allowance for Loan Losses (Details) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
Mar. 31, 2026	Mar. 31, 2025	Dec. 31, 2025
Allowance for loan losses:
Beginning balance	$ 442	$ 414	$ 414
Purchased credit deteriorated loans	237
Purchased seasoned loans	241
Charge-offs	(58)	(18)	(96)
Recoveries	9	4
Provision for (reversal of) loan losses	71	17
Ending balance	942	417	442
Commercial & Industrial
Allowance for loan losses:
Beginning balance	255	221	221
Purchased credit deteriorated loans	110
Purchased seasoned loans	106
Charge-offs	(45)	(15)
Recoveries	4	2
Provision for (reversal of) loan losses	60	21
Ending balance	489	230	255
Commercial Real Estate
Allowance for loan losses:
Beginning balance	95	111	111
Purchased credit deteriorated loans	102
Purchased seasoned loans	67
Charge-offs	0	0
Recoveries	0	0
Provision for (reversal of) loan losses	(48)	(12)
Ending balance	217	99	95
Consumer
Allowance for loan losses:
Beginning balance	92	82	82
Purchased credit deteriorated loans	25
Purchased seasoned loans	68
Charge-offs	(12)	(3)
Recoveries	4	2
Provision for (reversal of) loan losses	58	9
Ending balance	$ 236	$ 89	$ 92

Financing Receivable, Allowance for Credit Loss, Purchased Seasoned Loan

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

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

+ References

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

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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.

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Amount, excluding accrued interest, of allowance for credit loss at acquisition date of financing receivable purchased with credit deterioration. Excludes net investment in lease.

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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.

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