Fair Value Option - Summary of Fair Value and Unpaid Principal Balance (Details) - USD ($) $ in Millions	Jun. 30, 2025	Dec. 31, 2024
Fair Value, Option, Quantitative Disclosures [Line Items]
Client share repurchase asset, Fair Value	$ 117	$ 16
Client shares repurchase liability, Fair Value	117	16
Student loans held for investment
Fair Value, Option, Quantitative Disclosures [Line Items]
Loans, designated under fair value option	9	11
Loans held for investment, Unpaid Principal Balance	11	13
Fair Value Over (Under) Unpaid Principal Balance	(2)	(2)
Commercial loans held for sale
Fair Value, Option, Quantitative Disclosures [Line Items]
Commercial loans held for sale, Fair Value	419	395
Commercial loans held for sale, Unpaid Principal Balance	437	399
Fair Value Over (Under) Unpaid Principal Balance	(18)	(4)
Client share repurchase asset
Fair Value, Option, Quantitative Disclosures [Line Items]
Client share repurchase asset, Fair Value	117	16
Client share repurchase asset, Unpaid Principal Balance	117	16
Fair Value Over (Under) Unpaid Principal Balance	0	0
Fixed rate long-term debt
Fair Value, Option, Quantitative Disclosures [Line Items]
Fixed rate long-term debt, Fair Value	867	851
Fixed rate long-term debt, Unpaid Principal Balance	836	847
Fair Value Over (Under) Unpaid Principal Balance	31	4
Fixed rate long-term debt \| Structured notes
Fair Value, Option, Quantitative Disclosures [Line Items]
Hybrid instruments, structured notes, Fair Value	7,297	7,044
Hybrid instruments, Unpaid Principal Balance	7,116	6,888
Fair Value Over (Under) Unpaid Principal Balance	181	156
Structured deposits
Fair Value, Option, Quantitative Disclosures [Line Items]
Hybrid instruments, structured deposits, Fair Value	4,981	3,956
Hybrid instruments, Unpaid Principal Balance	4,816	3,892
Fair Value Over (Under) Unpaid Principal Balance	165	64
Client share repurchase liability
Fair Value, Option, Quantitative Disclosures [Line Items]
Client shares repurchase liability, Fair Value	117	16
Unpaid Principal Balance, Other Liabilities, Fair Value Disclosure	117	16
Fair Value Over (Under) Unpaid Principal Balance	$ 0	$ 0

Fair Value, Option, Loans Held As Assets

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Fair Value Over (Under) Unpaid Principal Balance

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Fixed-rate debt accounted for under fair value option.

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Unpaid Principal Balance Commercial Syndicated Loans Held For Sale Carried At Fair Value

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Unpaid Principal Balance, Loans Receivable

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Unpaid Principal Balance, Other Assets, Fair Value Disclosure

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Unpaid Principal Balance, Other Liabilities, Fair Value Disclosure

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Fair value portion of deposit liabilities held by the entity, including, but not limited to, foreign and domestic, interest and noninterest bearing, demand deposits, saving deposits, negotiable orders of withdrawal (NOW) and time deposits.

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Fair value portion of loans held-for-sale including, but not limited to, mortgage loans and finance receivables.

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The fair value amount of long-term debt whether such amount is presented as a separate caption or as a parenthetical disclosure. Additionally, this element may be used in connection with the fair value disclosures required in the footnote disclosures to the financial statements. The element may be used in both the balance sheet and disclosure in the same submission.

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Fair value portion of other assets.

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