Derivative Financial Instruments and Hedging Activities - Fair Value (Details) - USD ($) $ in Millions	Mar. 31, 2020	Dec. 31, 2019
Derivatives, Fair Value [Line Items]
Fair value of assets (liabilities) available for offset	$ 685	$ 302
Other Assets [Member]
Derivatives, Fair Value [Line Items]
Derivative asset, Notional amount	120,899	108,673
Derivative asset, Fair value	1,524	636
Collateral available for netting against liability positions	270	89
Other Liabilities [Member]
Derivatives, Fair Value [Line Items]
Derivative liability, Fair value	1,250	519
Cash held for netting against asset positions	668	210
Designated as Hedging Instrument [Member] \| Fair Value Hedging [Member] \| Other Assets [Member] \| Interest Rate Swaps [Member] \| Level 2 [Member]
Derivatives, Fair Value [Line Items]
Derivative asset, Notional amount	8,681	9,458
Derivative asset, Fair value	640	234
Designated as Hedging Instrument [Member] \| Fair Value Hedging [Member] \| Other Assets [Member] \| Foreign Currency Swaps [Member] \| Level 2 [Member]
Derivatives, Fair Value [Line Items]
Derivative asset, Notional amount	1,755	1,796
Derivative asset, Fair value	0	22
Designated as Hedging Instrument [Member] \| Fair Value Hedging [Member] \| Other Liabilities [Member] \| Interest Rate Swaps [Member] \| Level 2 [Member]
Derivatives, Fair Value [Line Items]
Derivative liability, Fair value	0	23
Designated as Hedging Instrument [Member] \| Fair Value Hedging [Member] \| Other Liabilities [Member] \| Foreign Currency Swaps [Member] \| Level 2 [Member]
Derivatives, Fair Value [Line Items]
Derivative liability, Fair value	84	71
Designated as Hedging Instrument [Member] \| Cash Flow Hedging [Member] \| Other Assets [Member] \| Interest Rate Swaps [Member] \| Level 2 [Member]
Derivatives, Fair Value [Line Items]
Derivative asset, Notional amount	1,090	590
Derivative asset, Fair value	0	0
Designated as Hedging Instrument [Member] \| Cash Flow Hedging [Member] \| Other Assets [Member] \| Foreign Currency Swaps [Member] \| Level 2 [Member]
Derivatives, Fair Value [Line Items]
Derivative asset, Notional amount	5,091	4,429
Derivative asset, Fair value	41	40
Designated as Hedging Instrument [Member] \| Cash Flow Hedging [Member] \| Other Liabilities [Member] \| Interest Rate Swaps [Member] \| Level 2 [Member]
Derivatives, Fair Value [Line Items]
Derivative liability, Fair value	21	6
Designated as Hedging Instrument [Member] \| Cash Flow Hedging [Member] \| Other Liabilities [Member] \| Foreign Currency Swaps [Member] \| Level 2 [Member]
Derivatives, Fair Value [Line Items]
Derivative liability, Fair value	373	119
Not Designated as Hedging Instrument [Member] \| Other Assets [Member] \| Interest Rate Contracts [Member] \| Level 2 [Member]
Derivatives, Fair Value [Line Items]
Derivative asset, Notional amount	104,282	92,400
Derivative asset, Fair value	843	340
Not Designated as Hedging Instrument [Member] \| Other Liabilities [Member] \| Interest Rate Contracts [Member] \| Level 2 [Member]
Derivatives, Fair Value [Line Items]
Derivative liability, Fair value	$ 772	$ 300

Derivative Assets (Liabilities), Net, Fair Value, Amount Not Offset Against Collateral

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- Definition

Nominal or face amount used to calculate payments on the derivative asset.

+ References

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Fair value, after the 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 not subject to a master netting arrangement and not elected to be offset.

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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 offset against derivative liabilities.

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- Definition

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.

+ References

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