Derivatives and Hedging Activities (Details) - USD ($) $ in Millions	Mar. 31, 2020	Dec. 31, 2019
Derivatives, Fair Value [Line Items]
Total fair value of derivative assets	$ 2,206	$ 343
Total fair value of derivative liabilities	419	440
Derivative asset and derivative liability netting, assets	(266)	(90)
Derivative asset and derivative liability netting, liabilities	(266)	(90)
Other Assets [Member]
Derivatives, Fair Value [Line Items]
Total derivatives assets, net	1,311	68
Cash collateral netting, assets	(629)	(185)
Other Assets [Member] \| Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Total fair value of derivative assets	1,380	209
Other Assets [Member] \| Interest Rate Contract [Member] \| Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Total derivatives assets, net	617	185
Other Assets [Member] \| Foreign Exchange Contract [Member] \| Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Total derivatives assets, net	763	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	826	134
Other Liabilities [Member]
Derivatives, Fair Value [Line Items]
Total derivative liabilities, net	153	341
Cash collateral netting, liabilities	0	(9)
Other Liabilities [Member] \| Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Total fair value of derivative liabilities	63	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	63	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	$ 356	$ 254

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