Derivative Financial Instruments and Hedging Activities (Details) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023	Dec. 31, 2023
Derivative [Line Items]
Debt Carrying Value Fair Value	$ 42,000,000,000.0		$ 42,000,000,000.0		$ 38,700,000,000
Income Effect of Derivative Financial Instruments [Abstract]
Derivative, Gain (Loss) on Derivative, Net	(139,000,000)	$ (133,000,000)	(315,000,000)	$ (262,000,000)
Balance Sheet Effect of Derivative Financial Instruments [Abstract]
Fair Value of Derivative Assets	689,000,000		689,000,000		818,000,000
Fair Value of Derivative Liabilities	2,077,000,000		2,077,000,000		2,141,000,000
Derivative, Notional Amount	111,440,000,000		111,440,000,000		104,707,000,000
Derivative, Collateral, Obligation to Return Cash	22,000,000		22,000,000		40,000,000
Derivative, Collateral, Right to Reclaim Cash	119,000,000		119,000,000		126,000,000
Derivative Asset, Not Offset, Policy Election Deduction	355,000,000		355,000,000		516,000,000
Derivative Liability, Not Offset, Policy Election Deduction	355,000,000		355,000,000		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	(106,000,000)	(130,000,000)	(202,000,000)	(270,000,000)
Change in Unrealized Gain (Loss) on Fair Value Hedging Instruments	(26,000,000)	(316,000,000)	(269,000,000)	(66,000,000)
Change in Unrealized Gain (Loss) on Hedged Item in Fair Value Hedge	17,000,000	292,000,000	237,000,000	13,000,000
Balance Sheet Effect of Derivative Financial Instruments [Abstract]
Derivative, Notional Amount	17,311,000,000		17,311,000,000		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	(35,000,000)	(19,000,000)	(64,000,000)	(33,000,000)
Change in Unrealized Gain (Loss) on Fair Value Hedging Instruments	(47,000,000)	(24,000,000)	(111,000,000)	(2,000,000)
Change in Unrealized Gain (Loss) on Hedged Item in Fair Value Hedge	40,000,000	22,000,000	102,000,000	3,000,000
Balance Sheet Effect of Derivative Financial Instruments [Abstract]
Derivative, Notional Amount	3,802,000,000		3,802,000,000		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	81,000,000		81,000,000		106,000,000
Fair Value of Derivative Liabilities	807,000,000		807,000,000		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	16,000,000		16,000,000		69,000,000
Fair Value of Derivative Liabilities	139,000,000		139,000,000		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	3,000,000	109,000,000	51,000,000	97,000,000
Balance Sheet Effect of Derivative Financial Instruments [Abstract]
Derivative, Notional Amount	72,746,000,000		72,746,000,000		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	397,000,000		397,000,000		465,000,000
Fair Value of Derivative Liabilities	860,000,000		860,000,000		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	36,000,000		36,000,000
Foreign Exchange Contract [Member] | Not Designated as Hedging Instrument [Member]
Income Effect of Derivative Financial Instruments [Abstract]
Derivative, Gain (Loss) on Derivative, Net	45,000,000	(7,000,000)	137,000,000	(29,000,000)
Balance Sheet Effect of Derivative Financial Instruments [Abstract]
Derivative, Notional Amount	12,280,000,000		12,280,000,000		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	8,400,000,000		8,400,000,000
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	113,000,000		113,000,000		59,000,000
Fair Value of Derivative Liabilities	37,000,000		37,000,000		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	36,000,000		36,000,000
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	(30,000,000)	$ (60,000,000)	(196,000,000)	$ 25,000,000
Balance Sheet Effect of Derivative Financial Instruments [Abstract]
Derivative, Notional Amount	5,301,000,000		5,301,000,000		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	82,000,000		82,000,000		119,000,000
Fair Value of Derivative Liabilities	$ 234,000,000		$ 234,000,000		$ 252,000,000