Derivative Financial Instruments and Hedging Activities (Details) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Income Effect of Derivative Financial Instruments [Abstract]
Derivative, Gain (Loss) on Derivative, Net	$ (35)	$ 594	$ (194)
Balance Sheet Effect of Derivative Financial Instruments [Abstract]
Fair Value of Derivative Assets	1,065	2,601
Fair Value of Derivative Liabilities	512	524
Derivative, Collateral, Obligation to Return Cash	26	9
Derivative, Collateral, Right to Reclaim Cash	71	96
Derivative Asset, Not Offset, Policy Election Deduction	415	204
Derivative, Notional Amount	85,778	109,354
Interest Rate Contract [Member] \| Not Designated as Hedging Instrument [Member]
Income Effect of Derivative Financial Instruments [Abstract]
Derivative, Gain (Loss) on Derivative, Net	(3)	(100)	(13)
Balance Sheet Effect of Derivative Financial Instruments [Abstract]
Derivative, Notional Amount	50,060	70,318
Interest Rate Contract [Member] \| Fair Value Hedging [Member] \| Designated as Hedging Instrument [Member]
Income Effect of Derivative Financial Instruments [Abstract]
Net interest settlements and accruals excluded from the assessment of hedge effectiveness	393	290	(16)
Change in Unrealized Gain (Loss) on Fair Value Hedging Instruments	(1,001)	986	706
Change in Unrealized Gain (Loss) on Hedged Item in Fair Value Hedge	957	(985)	(694)
Balance Sheet Effect of Derivative Financial Instruments [Abstract]
Derivative, Notional Amount	23,893	26,924
Interest Rate Contract [Member] \| Currency Swap [Member] \| Designated as Hedging Instrument [Member]
Income Effect of Derivative Financial Instruments [Abstract]
Net interest settlements and accruals excluded from the assessment of hedge effectiveness	(8)	(2)	0
Change in Unrealized Gain (Loss) on Fair Value Hedging Instruments	(93)	38	0
Change in Unrealized Gain (Loss) on Hedged Item in Fair Value Hedge	82	(37)	0
Foreign Exchange Contract [Member] \| Not Designated as Hedging Instrument [Member]
Income Effect of Derivative Financial Instruments [Abstract]
Derivative, Gain (Loss) on Derivative, Net	145	(82)	52
Balance Sheet Effect of Derivative Financial Instruments [Abstract]
Derivative, Notional Amount	4,407	4,378
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	(507)	486	$ (229)
Balance Sheet Effect of Derivative Financial Instruments [Abstract]
Derivative, Notional Amount	6,533	6,849
Cross Currency Interest Rate Contract [Member] \| Fair Value Hedging [Member] \| Designated as Hedging Instrument [Member]
Balance Sheet Effect of Derivative Financial Instruments [Abstract]
Derivative, Notional Amount	885	885
Level 2 [Member] \| Fair Value, Measurements, Recurring [Member] \| Interest Rate Contract [Member] \| Not Designated as Hedging Instrument [Member]
Balance Sheet Effect of Derivative Financial Instruments [Abstract]
Fair Value of Derivative Assets	338	663
Fair Value of Derivative Liabilities	126	439
Level 2 [Member] \| Fair Value, Measurements, Recurring [Member] \| Interest Rate Contract [Member] \| Fair Value Hedging [Member] \| Designated as Hedging Instrument [Member]
Balance Sheet Effect of Derivative Financial Instruments [Abstract]
Fair Value of Derivative Assets	544	1,331
Fair Value of Derivative Liabilities	274	4
Level 2 [Member] \| Fair Value, Measurements, Recurring [Member] \| Foreign Exchange Contract [Member] \| Not Designated as Hedging Instrument [Member]
Balance Sheet Effect of Derivative Financial Instruments [Abstract]
Fair Value of Derivative Assets	66	4
Fair Value of Derivative Liabilities	2	80
Level 2 [Member] \| Fair Value, Measurements, Recurring [Member] \| Cross Currency Interest Rate Contract [Member] \| Not Designated as Hedging Instrument [Member]
Balance Sheet Effect of Derivative Financial Instruments [Abstract]
Fair Value of Derivative Assets	117	557
Fair Value of Derivative Liabilities	61	1
Level 2 [Member] \| Fair Value, Measurements, Recurring [Member] \| Cross Currency Interest Rate Contract [Member] \| Fair Value Hedging [Member] \| Designated as Hedging Instrument [Member]
Balance Sheet Effect of Derivative Financial Instruments [Abstract]
Fair Value of Derivative Assets	0	46
Fair Value of Derivative Liabilities	$ 49	$ 0

Balance Sheet Effect of Derivative Financial Instruments [Abstract]

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Income Effect of Derivative Financial Instruments [Abstract]

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Amount of gain (loss) from the increase (decrease) in fair value of derivative and nonderivative instruments designated as fair value hedging instruments recognized in the income statement.

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Amount of the increase (decrease) in fair value of the hedged item in a fair value hedge recognized in the income statement.

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Fair value of financial asset or other contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset, elected not to be offset, deducted from derivative assets.

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Amount of obligation to return cash collateral under master netting arrangements that have not been offset against derivative assets.

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