Balance Sheet Effect of Derivative Financial Instruments [Abstract]

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Fair value of hedged debt carried at cost which approximates fair value

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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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Amount of right to receive cash collateral under master netting arrangements that have not been offset against derivative liabilities.

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Fair value, before effects of master netting arrangements, of a 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. Includes assets elected not to be offset. Excludes assets not subject to a master netting arrangement.

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Fair value, before effects of master netting arrangements, of a financial liability or 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. Includes liabilities elected not to be offset. Excludes liabilities not subject to a master netting arrangement.

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Amount of increase (decrease) in the fair value of derivatives recognized in the income statement.

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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Nominal or face amount used to calculate payment on derivative.

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The net gain (loss) included in earnings for the period relating to components of the gain (loss) on interest rate fair value hedging instruments excluded from the assessment of fair value hedge effectiveness.

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Derivative Financial Instruments and Hedging Activities (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019	Dec. 31, 2019
Derivative [Line Items]
Debt Carrying Value Fair Value	$ 42,500		$ 42,500		$ 39,400
Income Effect of Derivative Financial Instruments [Abstract]
Derivative, Gain (Loss) on Derivative, Net	183	$ 177	210	$ (24)
Balance Sheet Effect of Derivative Financial Instruments [Abstract]
Fair Value of Derivative Assets	2,640		2,640		1,128
Fair Value of Derivative Liabilities	668		668		356
Derivative, Notional Amount	104,644		104,644		106,880
Derivative, Collateral, Obligation to Return Cash	20		20		18
Derivative, Collateral, Right to Reclaim Cash	91		91		78
Derivative Asset, Not Offset, Policy Election Deduction	337		337		169
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	68	(12)	96	(32)
Change in Unrealized Gain (Loss) on Fair Value Hedging Instruments	112	474	1,222	724
Change in Unrealized Gain (Loss) on Hedged Item in Fair Value Hedge	(98)	(463)	(1,191)	(716)
Balance Sheet Effect of Derivative Financial Instruments [Abstract]
Derivative, Notional Amount	24,434		24,434		26,577
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	1,682		1,682		702
Fair Value of Derivative Liabilities	0		0		19
Interest Rate Contract [Member] \| Not Designated as Hedging Instrument [Member]
Income Effect of Derivative Financial Instruments [Abstract]
Derivative, Gain (Loss) on Derivative, Net	(12)	(3)	(86)	(30)
Balance Sheet Effect of Derivative Financial Instruments [Abstract]
Derivative, Notional Amount	71,075		71,075		68,914
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	752		752		275
Fair Value of Derivative Liabilities	573		573		191
Foreign Exchange Contract [Member] \| Not Designated as Hedging Instrument [Member]
Income Effect of Derivative Financial Instruments [Abstract]
Derivative, Gain (Loss) on Derivative, Net	(41)	40	166	34
Balance Sheet Effect of Derivative Financial Instruments [Abstract]
Derivative, Notional Amount	3,524		3,524		5,540
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	43		43		17
Fair Value of Derivative Liabilities	42		42		79
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	154	$ 141	3	$ (4)
Balance Sheet Effect of Derivative Financial Instruments [Abstract]
Derivative, Notional Amount	5,611		5,611		5,849
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	163		163		134
Fair Value of Derivative Liabilities	$ 53		$ 53		$ 67