Derivatives and Hedging Activities (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Derivatives, Fair Value [Line Items]
Total derivative assets, gross	$ 629	$ 343
Total derivative liabilities, gross	702	440
Derivative asset and derivative liability netting, assets	(98)	(90)
Derivative asset and derivative liability netting, liabilities	(98)	(90)
Cash collateral netting, assets	(500)	(185)
Cash collateral netting, liabilities	(16)	(9)
Total derivatives assets, net	31	68
Total derivatives liabilities, net	588	341
Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Total derivatives liabilities, net	16,400	22,700
Other Assets [Member] | Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Total derivative assets, gross	524	209
Other Assets [Member] | Interest Rate Contract [Member] | Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Total derivative assets, gross	500	185
Other Assets [Member] | Foreign Exchange Contract [Member] | Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Total derivative assets, gross	24	24
Other Assets [Member] | Foreign Exchange Contract [Member] | Not Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Total derivative assets, gross	105	134
Other Liabilities [Member] | Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Total derivative liabilities, gross	474	186
Other Liabilities [Member] | Interest Rate Contract [Member] | Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Total derivative liabilities, gross	0	0
Other Liabilities [Member] | Foreign Exchange Contract [Member] | Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Total derivative liabilities, gross	474	186
Other Liabilities [Member] | Foreign Exchange Contract [Member] | Not Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Total derivative liabilities, gross	$ 228	$ 254