Derivative Financial Instruments - Fair Value of Derivatives and Balance Offsetting (Details) - USD ($) $ in Millions	Sep. 30, 2024	Dec. 31, 2023
Derivatives, Fair Value [Line Items]
Derivative Assets	$ 12,832	$ 17,169
Derivative Liabilities	13,299	17,263
Gross amounts of receivable subject to enforceable master netting agreements	10,428	14,110
Gross amounts of payable subject to enforceable master netting agreements	10,428	14,110
Less: Gross amounts of cash collateral received subject to enforceable master netting agreements	1,170	1,760
Less: Gross amounts of cash collateral posted subject to enforceable master netting agreements	1,511	1,321
Derivative asset	1,234	1,299
Derivative liability	1,360	1,832
Less: Gross amounts of financial instrument collateral received not offset	151	63
Less: Gross amounts of financial instrument collateral posted not offset	36	273
Net amount of derivative asset	1,083	1,236
Net amount of derivative liability	$ 1,324	$ 1,559
Derivative Liability, Statement of Financial Position [Extensible Enumeration]	Interest, taxes and other liabilities (includes nil and $10 million designated under fair value option at September 30, 2024 and December 31, 2023, respectively)	Interest, taxes and other liabilities (includes nil and $10 million designated under fair value option at September 30, 2024 and December 31, 2023, respectively)
Derivative Asset, Statement of Financial Position [Extensible Enumeration]	Other assets, net of allowance for credit losses of nil at both September 30, 2024 and December 31, 2023 (includes nil and $10 million designated under fair value option at September 30, 2024 and December 31, 2023, respectively)	Other assets, net of allowance for credit losses of nil at both September 30, 2024 and December 31, 2023 (includes nil and $10 million designated under fair value option at September 30, 2024 and December 31, 2023, respectively)
Trading Assets
Derivatives, Fair Value [Line Items]
Less: Gross amounts of cash collateral received subject to enforceable master netting agreements	$ 889	$ 1,416
Trading Liabilities
Derivatives, Fair Value [Line Items]
Less: Gross amounts of cash collateral posted subject to enforceable master netting agreements	1,511	1,321
Designated as Hedging Instrument | Other assets
Derivatives, Fair Value [Line Items]
Derivative Assets	6	0
Designated as Hedging Instrument | Interest taxes and other liabilities
Derivatives, Fair Value [Line Items]
Derivative Liabilities	66	140
Interest rate contracts | Not Designated as Hedging Instrument, Trading | Trading Assets
Derivatives, Fair Value [Line Items]
Derivative Assets	905	1,255
Interest rate contracts | Not Designated as Hedging Instrument, Trading | Trading Liabilities
Derivatives, Fair Value [Line Items]
Derivative Liabilities	692	962
Foreign exchange contracts | Not Designated as Hedging Instrument, Trading | Trading Assets
Derivatives, Fair Value [Line Items]
Derivative Assets	9,569	13,606
Foreign exchange contracts | Not Designated as Hedging Instrument, Trading | Trading Liabilities
Derivatives, Fair Value [Line Items]
Derivative Liabilities	9,623	13,479
Equity contracts | Not Designated as Hedging Instrument, Trading | Trading Assets
Derivatives, Fair Value [Line Items]
Derivative Assets	395	420
Equity contracts | Not Designated as Hedging Instrument, Trading | Trading Liabilities
Derivatives, Fair Value [Line Items]
Derivative Liabilities	1,148	1,080
Precious metals contracts | Not Designated as Hedging Instrument, Trading | Trading Assets
Derivatives, Fair Value [Line Items]
Derivative Assets	1,288	1,153
Precious metals contracts | Not Designated as Hedging Instrument, Trading | Trading Liabilities
Derivatives, Fair Value [Line Items]
Derivative Liabilities	1,271	1,033
Credit contracts | Not Designated as Hedging Instrument, Trading | Trading Assets
Derivatives, Fair Value [Line Items]
Derivative Assets	111	95
Credit contracts | Not Designated as Hedging Instrument, Trading | Trading Liabilities
Derivatives, Fair Value [Line Items]
Derivative Liabilities	137	137
Credit contracts | Not Designated as Hedging Instrument, Other | Other assets
Derivatives, Fair Value [Line Items]
Derivative Assets	11	14
Credit contracts | Not Designated as Hedging Instrument, Other | Interest taxes and other liabilities
Derivatives, Fair Value [Line Items]
Derivative Liabilities	128	123
Bilateral OTC | Interest rate contracts | Not Designated as Hedging Instrument, Trading | Trading Assets
Derivatives, Fair Value [Line Items]
Derivative Assets	797	1,178
Bilateral OTC | Interest rate contracts | Not Designated as Hedging Instrument, Trading | Trading Liabilities
Derivatives, Fair Value [Line Items]
Derivative Liabilities	691	946
Bilateral OTC | Interest rate contracts | Not Designated as Hedging Instrument, Other | Other assets
Derivatives, Fair Value [Line Items]
Derivative Assets	0	0
Bilateral OTC | Interest rate contracts | Not Designated as Hedging Instrument, Other | Interest taxes and other liabilities
Derivatives, Fair Value [Line Items]
Derivative Liabilities	62	76
Bilateral OTC | Foreign exchange contracts | Not Designated as Hedging Instrument, Trading | Trading Assets
Derivatives, Fair Value [Line Items]
Derivative Assets	9,483	13,606
Bilateral OTC | Foreign exchange contracts | Not Designated as Hedging Instrument, Trading | Trading Liabilities
Derivatives, Fair Value [Line Items]
Derivative Liabilities	9,623	13,479
Bilateral OTC | Equity contracts | Not Designated as Hedging Instrument, Trading | Trading Assets
Derivatives, Fair Value [Line Items]
Derivative Assets	390	413
Bilateral OTC | Equity contracts | Not Designated as Hedging Instrument, Trading | Trading Liabilities
Derivatives, Fair Value [Line Items]
Derivative Liabilities	1,148	1,080
Bilateral OTC | Equity contracts | Not Designated as Hedging Instrument, Other | Other assets
Derivatives, Fair Value [Line Items]
Derivative Assets	536	621
Bilateral OTC | Equity contracts | Not Designated as Hedging Instrument, Other | Interest taxes and other liabilities
Derivatives, Fair Value [Line Items]
Derivative Liabilities	116	193
Bilateral OTC | Precious metals contracts | Not Designated as Hedging Instrument, Trading | Trading Assets
Derivatives, Fair Value [Line Items]
Derivative Assets	1,288	1,150
Bilateral OTC | Precious metals contracts | Not Designated as Hedging Instrument, Trading | Trading Liabilities
Derivatives, Fair Value [Line Items]
Derivative Liabilities	1,271	1,033
Bilateral OTC | Credit contracts | Not Designated as Hedging Instrument, Trading | Trading Assets
Derivatives, Fair Value [Line Items]
Derivative Assets	111	81
Bilateral OTC | Credit contracts | Not Designated as Hedging Instrument, Trading | Trading Liabilities
Derivatives, Fair Value [Line Items]
Derivative Liabilities	137	137
Bilateral OTC | Credit contracts | Not Designated as Hedging Instrument, Other | Other assets
Derivatives, Fair Value [Line Items]
Derivative Assets	11	13
Bilateral OTC | Credit contracts | Not Designated as Hedging Instrument, Other | Interest taxes and other liabilities
Derivatives, Fair Value [Line Items]
Derivative Liabilities	128	122
Bilateral OTC | Other Contracts | Not Designated as Hedging Instrument, Other | Other assets
Derivatives, Fair Value [Line Items]
Derivative Assets	11	5
Bilateral OTC | Other Contracts | Not Designated as Hedging Instrument, Other | Interest taxes and other liabilities
Derivatives, Fair Value [Line Items]
Derivative Liabilities	56	40
Bilateral OTC | Fair Value Hedging | Interest rate contracts | Designated as Hedging Instrument | Other assets
Derivatives, Fair Value [Line Items]
Derivative Assets	2	0
Bilateral OTC | Fair Value Hedging | Interest rate contracts | Designated as Hedging Instrument | Interest taxes and other liabilities
Derivatives, Fair Value [Line Items]
Derivative Liabilities	2	83
Bilateral OTC | Cash Flow Hedging | Interest rate contracts | Designated as Hedging Instrument | Other assets
Derivatives, Fair Value [Line Items]
Derivative Assets	0	0
Bilateral OTC | Cash Flow Hedging | Interest rate contracts | Designated as Hedging Instrument | Interest taxes and other liabilities
Derivatives, Fair Value [Line Items]
Derivative Liabilities	2	1
Bilateral OTC | Cash Flow Hedging | Foreign exchange contracts | Designated as Hedging Instrument | Other assets
Derivatives, Fair Value [Line Items]
Derivative Assets	4	0
Bilateral OTC | Cash Flow Hedging | Foreign exchange contracts | Designated as Hedging Instrument | Interest taxes and other liabilities
Derivatives, Fair Value [Line Items]
Derivative Liabilities	62	56
OTC Cleared | Interest rate contracts | Not Designated as Hedging Instrument, Trading | Trading Assets
Derivatives, Fair Value [Line Items]
Derivative Assets	101	70
OTC Cleared | Interest rate contracts | Not Designated as Hedging Instrument, Trading | Trading Liabilities
Derivatives, Fair Value [Line Items]
Derivative Liabilities	0	0
OTC Cleared | Foreign exchange contracts | Not Designated as Hedging Instrument, Trading | Trading Assets
Derivatives, Fair Value [Line Items]
Derivative Assets	86	0
OTC Cleared | Foreign exchange contracts | Not Designated as Hedging Instrument, Trading | Trading Liabilities
Derivatives, Fair Value [Line Items]
Derivative Liabilities	0	0
OTC Cleared | Credit contracts | Not Designated as Hedging Instrument, Trading | Trading Assets
Derivatives, Fair Value [Line Items]
Derivative Assets	0	14
OTC Cleared | Credit contracts | Not Designated as Hedging Instrument, Trading | Trading Liabilities
Derivatives, Fair Value [Line Items]
Derivative Liabilities	0	0
OTC Cleared | Credit contracts | Not Designated as Hedging Instrument, Other | Other assets
Derivatives, Fair Value [Line Items]
Derivative Assets	0	1
OTC Cleared | Credit contracts | Not Designated as Hedging Instrument, Other | Interest taxes and other liabilities
Derivatives, Fair Value [Line Items]
Derivative Liabilities	0	1
Exchange Traded | Interest rate contracts | Not Designated as Hedging Instrument, Trading | Trading Assets
Derivatives, Fair Value [Line Items]
Derivative Assets	7	7
Exchange Traded | Interest rate contracts | Not Designated as Hedging Instrument, Trading | Trading Liabilities
Derivatives, Fair Value [Line Items]
Derivative Liabilities	1	16
Exchange Traded | Equity contracts | Not Designated as Hedging Instrument, Trading | Trading Assets
Derivatives, Fair Value [Line Items]
Derivative Assets	5	7
Exchange Traded | Equity contracts | Not Designated as Hedging Instrument, Trading | Trading Liabilities
Derivatives, Fair Value [Line Items]
Derivative Liabilities	0	0
Exchange Traded | Precious metals contracts | Not Designated as Hedging Instrument, Trading | Trading Assets
Derivatives, Fair Value [Line Items]
Derivative Assets	0	3
Exchange Traded | Precious metals contracts | Not Designated as Hedging Instrument, Trading | Trading Liabilities
Derivatives, Fair Value [Line Items]
Derivative Liabilities	$ 0	$ 0