Debt (Pledged Assets Related to Secured Borrowings and Repurchase Agreement) (Details) - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022
Pledged Assets related to secured borrowings [Line Items]
Total assets restricted as collateral	$ 69,512	$ 39,265
Secured debt	10,443	10,124
Amortized cost	28,416	34,863
Short-term borrowings	3,297	2,399
Asset Pledged as Collateral
Pledged Assets related to secured borrowings [Line Items]
Amortized cost	4,030	4,288
Pledged assets for Federal Home Loan Bank
Pledged Assets related to secured borrowings [Line Items]
Total assets restricted as collateral	27,900	27,000
Pledged assets for Federal Reserve Bank
Pledged Assets related to secured borrowings [Line Items]
Total assets restricted as collateral	34,000	2,400
Investment securities
Pledged Assets related to secured borrowings [Line Items]
Total assets restricted as collateral	4,036	3,525
Consumer \| Automotive
Pledged Assets related to secured borrowings [Line Items]
Total assets restricted as collateral	40,805	11,759
Consumer \| Consumer mortgage
Pledged Assets related to secured borrowings [Line Items]
Total assets restricted as collateral	18,703	19,771
Commercial
Pledged Assets related to secured borrowings [Line Items]
Total assets restricted as collateral	$ 5,968	$ 4,210

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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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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