Derivative Financial Instruments and Hedging Activities (Details) - USD ($)	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023	Dec. 31, 2023
Derivative [Line Items]
Debt Carrying Value Fair Value	$ 40,300,000,000		$ 38,700,000,000
Income Effect of Derivative Financial Instruments [Abstract]
Derivative, Gain (Loss) on Derivative, Net	(176,000,000)	$ (129,000,000)
Balance Sheet Effect of Derivative Financial Instruments [Abstract]
Fair Value of Derivative Assets	812,000,000		818,000,000
Fair Value of Derivative Liabilities	2,152,000,000		2,141,000,000
Derivative, Notional Amount	110,055,000,000		104,707,000,000
Derivative, Collateral, Obligation to Return Cash	33,000,000		40,000,000
Derivative, Collateral, Right to Reclaim Cash	108,000,000		126,000,000
Derivative Asset, Not Offset, Policy Election Deduction	471,000,000		516,000,000
Derivative Liability, Not Offset, Policy Election Deduction	471,000,000		516,000,000
Interest Rate Contract [Member] | Designated as Hedging Instrument [Member] | Fair Value Hedging [Member]
Income Effect of Derivative Financial Instruments [Abstract]
Net interest settlements and accruals excluded from the assessment of hedge effectiveness	(96,000,000)	(140,000,000)
Change in Unrealized Gain (Loss) on Fair Value Hedging Instruments	(243,000,000)	250,000,000
Change in Unrealized Gain (Loss) on Hedged Item in Fair Value Hedge	220,000,000	(279,000,000)
Balance Sheet Effect of Derivative Financial Instruments [Abstract]
Derivative, Notional Amount	16,307,000,000		12,119,000,000
Interest Rate Contract [Member] | Designated as Hedging Instrument [Member] | Currency Swap
Income Effect of Derivative Financial Instruments [Abstract]
Net interest settlements and accruals excluded from the assessment of hedge effectiveness	(29,000,000)	(14,000,000)
Change in Unrealized Gain (Loss) on Fair Value Hedging Instruments	(64,000,000)	22,000,000
Change in Unrealized Gain (Loss) on Hedged Item in Fair Value Hedge	62,000,000	(19,000,000)
Balance Sheet Effect of Derivative Financial Instruments [Abstract]
Derivative, Notional Amount	3,155,000,000		2,078,000,000
Interest Rate Contract [Member] | Designated as Hedging Instrument [Member] | Level 2 [Member] | Fair Value, Recurring [Member] | Fair Value Hedging [Member]
Balance Sheet Effect of Derivative Financial Instruments [Abstract]
Fair Value of Derivative Assets	84,000,000		106,000,000
Fair Value of Derivative Liabilities	769,000,000		633,000,000
Interest Rate Contract [Member] | Designated as Hedging Instrument [Member] | Level 2 [Member] | Fair Value, Recurring [Member] | Currency Swap
Balance Sheet Effect of Derivative Financial Instruments [Abstract]
Fair Value of Derivative Assets	41,000,000		69,000,000
Fair Value of Derivative Liabilities	115,000,000		104,000,000
Interest Rate Contract [Member] | Not Designated as Hedging Instrument [Member]
Income Effect of Derivative Financial Instruments [Abstract]
Derivative, Gain (Loss) on Derivative, Net	48,000,000	(12,000,000)
Balance Sheet Effect of Derivative Financial Instruments [Abstract]
Derivative, Notional Amount	73,109,000,000		73,134,000,000
Interest Rate Contract [Member] | Not Designated as Hedging Instrument [Member] | Level 2 [Member] | Fair Value, Recurring [Member]
Balance Sheet Effect of Derivative Financial Instruments [Abstract]
Fair Value of Derivative Assets	489,000,000		465,000,000
Fair Value of Derivative Liabilities	928,000,000		1,036,000,000
Interest Rate Contract [Member] | Not Designated as Hedging Instrument [Member] | Level 2 [Member] | Fair Value, Recurring [Member] | Affiliated Entity
Balance Sheet Effect of Derivative Financial Instruments [Abstract]
Fair Value of Derivative Assets	46,000,000
Foreign Exchange Contract [Member] | Not Designated as Hedging Instrument [Member]
Income Effect of Derivative Financial Instruments [Abstract]
Derivative, Gain (Loss) on Derivative, Net	92,000,000	(22,000,000)
Balance Sheet Effect of Derivative Financial Instruments [Abstract]
Derivative, Notional Amount	10,955,000,000		10,276,000,000
Foreign Exchange Contract [Member] | Not Designated as Hedging Instrument [Member] | Affiliated Entity
Balance Sheet Effect of Derivative Financial Instruments [Abstract]
Derivative, Notional Amount	7,300,000,000
Foreign Exchange Contract [Member] | Not Designated as Hedging Instrument [Member] | Level 2 [Member] | Fair Value, Recurring [Member]
Balance Sheet Effect of Derivative Financial Instruments [Abstract]
Fair Value of Derivative Assets	99,000,000		59,000,000
Fair Value of Derivative Liabilities	49,000,000		116,000,000
Foreign Exchange Contract [Member] | Not Designated as Hedging Instrument [Member] | Level 2 [Member] | Fair Value, Recurring [Member] | Affiliated Entity
Balance Sheet Effect of Derivative Financial Instruments [Abstract]
Fair Value of Derivative Liabilities	46,000,000
Cross Currency Interest Rate Contract [Member] | Not Designated as Hedging Instrument [Member]
Income Effect of Derivative Financial Instruments [Abstract]
Derivative, Gain (Loss) on Derivative, Net	(166,000,000)	$ 85,000,000
Balance Sheet Effect of Derivative Financial Instruments [Abstract]
Derivative, Notional Amount	6,529,000,000		7,100,000,000
Cross Currency Interest Rate Contract [Member] | Not Designated as Hedging Instrument [Member] | Level 2 [Member] | Fair Value, Recurring [Member]
Balance Sheet Effect of Derivative Financial Instruments [Abstract]
Fair Value of Derivative Assets	99,000,000		119,000,000
Fair Value of Derivative Liabilities	$ 291,000,000		$ 252,000,000