Guarantee Arrangements and Pledged Assets and Repurchase Agreements - Offsetting of Resale and Repurchase Agreements and Securities Borrowing and Lending Agreements (Details) - USD ($) $ in Millions	Mar. 31, 2024	Dec. 31, 2023
Commitments and Contingencies Disclosure [Abstract]
Securities purchased under agreements to resell, Gross Amounts Recognized	$ 12,557	$ 19,382
Securities purchased under agreements to resell, Gross Amounts Offset in the Balance Sheet	4,251	5,504
Securities purchased under agreements to resell, Net amounts Presented in the Balance Sheet	8,306	13,878
Securities purchased under agreements to resell, Gross Amounts Not Offset in the Balance Sheet, Financial Instruments	8,281	13,677
Securities purchased under agreements to resell, Gross Amounts Not Offset in the Balance Sheet, Cash Collateral Receive / Pledged	16	7
Securities purchased under agreements to resell, Net amount	9	194
Securities sold under repurchase agreements, Gross Amounts Recognized	4,631	5,771
Securities sold under repurchase agreements, Gross Amounts Offset in the Balance Sheet	4,251	5,504
Securities sold under repurchase agreements, Net Amounts Presented in the Balance Sheet	380	267
Securities sold under repurchase agreements, Gross Amounts Not Offset in the Balance sheet, Financial Instruments	380	266
Securities sold under repurchase agreements, Gross Amounts Not Offset in the Balance Sheet, Cash Collateral Received / Pledged	0	0
Securities sold under repurchase agreements, Net amount	$ 0	$ 1