Derivatives and Hedging Activities (Details) - USD ($) $ in Millions	Jun. 30, 2020	Dec. 31, 2019
Derivatives, Fair Value [Line Items]
Total fair value of derivative assets	$ 1,070	$ 343
Total fair value of derivative liabilities	422	440
Derivative asset and derivative liability netting, assets	(237)	(90)
Derivative asset and derivative liability netting, liabilities	(237)	(90)
Other Assets [Member]
Derivatives, Fair Value [Line Items]
Total derivatives assets, net	205	68
Cash collateral netting, assets	(628)	(185)
Other Assets [Member] \| Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Total fair value of derivative assets	873	209
Other Assets [Member] \| Interest Rate Contract [Member] \| Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Total derivatives assets, net	624	185
Other Assets [Member] \| Foreign Exchange Contract [Member] \| Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Total derivatives assets, net	249	24
Other Assets [Member] \| Foreign Exchange Contract [Member] \| Not Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Total fair value of derivative assets	197	134
Other Liabilities [Member]
Derivatives, Fair Value [Line Items]
Total derivative liabilities, net	183	341
Cash collateral netting, liabilities	(2)	(9)
Other Liabilities [Member] \| Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Total fair value of derivative liabilities	151	186
Other Liabilities [Member] \| Interest Rate Contract [Member] \| Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Total derivative liabilities, net	0	0
Other Liabilities [Member] \| Foreign Exchange Contract [Member] \| Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Total derivative liabilities, net	151	186
Other Liabilities [Member] \| Foreign Exchange Contract [Member] \| Not Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Total fair value of derivative liabilities	$ 271	$ 254

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