Debt - Schedule of Pledged Assets Related to Secured Borrowings and Repurchase Agreement (Details) - USD ($) $ in Millions	Mar. 31, 2025	Dec. 31, 2024
Pledged Assets related to secured borrowings [Line Items]
Total assets restricted as collateral	$ 65,721	$ 65,497
Secured debt	9,226	8,058
Amortized cost	25,772	26,810
Short-term borrowings	3,339	1,625
Asset Pledged as Collateral
Pledged Assets related to secured borrowings [Line Items]
Amortized cost	3,657	2,822
Credit-Linked Notes
Pledged Assets related to secured borrowings [Line Items]
Total assets restricted as collateral	599	669
Pledged assets for Federal Home Loan Bank
Pledged Assets related to secured borrowings [Line Items]
Total assets restricted as collateral	26,700	26,500
Pledged assets for Federal Reserve Bank
Pledged Assets related to secured borrowings [Line Items]
Total assets restricted as collateral	33,700	33,800
Investment securities
Pledged Assets related to secured borrowings [Line Items]
Total assets restricted as collateral	3,810	2,946
Consumer \| Automotive
Pledged Assets related to secured borrowings [Line Items]
Total assets restricted as collateral	37,560	38,316
Consumer \| Consumer mortgage finance receivables
Pledged Assets related to secured borrowings [Line Items]
Total assets restricted as collateral	16,997	17,269
Commercial
Pledged Assets related to secured borrowings [Line Items]
Total assets restricted as collateral	$ 6,755	$ 6,297

Amount of assets pledged to secure a debt instrument.

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Amortized cost excluding accrued interest, after allowance for credit loss, of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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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.

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Carrying value as of the balance sheet date, including the current and noncurrent portions, of collateralized debt obligations (with maturities initially due after one year or beyond the operating cycle, if longer). Such obligations include mortgage loans, chattel loans, and any other borrowings secured by assets of the borrower.

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Reflects the total carrying amount as of the balance sheet date of debt having initial terms less than one year or the normal operating cycle, if longer.

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