Derivative Financial Instruments and Hedging Activities - Derivative Financial Instruments (Details) - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022
Derivatives, Fair Value [Line Items]
Notional	$ 163,446	$ 142,212
Fair Value of Assets	1,809	2,302
Fair Value of Liabilities	$ 2,563	$ 3,392
Derivative Asset, Statement of Financial Position [Extensible Enumeration]	Other assets (Note 8)	Other assets (Note 8)
Derivative Liability, Statement of Financial Position [Extensible Enumeration]	Other liabilities	Other liabilities
Fair value of assets (liabilities) available for offset	$ 1,200	$ 1,300
Other Liabilities
Derivatives, Fair Value [Line Items]
Cash held for netting against asset positions	457	553
Other Assets
Derivatives, Fair Value [Line Items]
Collateral available for netting against liability positions	1,200	1,500
Interest rate swaps | Fair value hedges | Level 2 | Derivatives Designated as Hedges
Derivatives, Fair Value [Line Items]
Notional	18,379	19,950
Fair Value of Assets	75	0
Fair Value of Liabilities	238	821
Interest rate swaps | Cash flow hedges | Level 2 | Derivatives Designated as Hedges
Derivatives, Fair Value [Line Items]
Notional	2,381	1,434
Fair Value of Assets	17	34
Fair Value of Liabilities	16	1
Foreign currency swaps | Cash flow hedges | Level 2 | Derivatives Designated as Hedges
Derivatives, Fair Value [Line Items]
Notional	8,003	6,852
Fair Value of Assets	144	0
Fair Value of Liabilities	311	586
Interest rate contracts | Level 2 | Derivatives not Designated as Hedges
Derivatives, Fair Value [Line Items]
Notional	134,683	113,975
Fair Value of Assets	1,573	2,268
Fair Value of Liabilities	$ 1,997	$ 1,984