Derivatives and Hedging Activities (Details) - USD ($) $ in Millions	Sep. 30, 2021	Dec. 31, 2020
Derivatives, Fair Value [Line Items]
Total fair value of derivative assets	$ 531	$ 629
Total fair value of derivative liabilities	119	702
Derivative asset and derivative liability netting, assets	(74)	(98)
Derivative asset and derivative liability netting, liabilities	(74)	(98)
Other Assets
Derivatives, Fair Value [Line Items]
Total derivatives assets, net	147	31
Cash collateral netting, assets	(310)	(500)
Other Assets | Designated as Hedging Instrument
Derivatives, Fair Value [Line Items]
Total fair value of derivative assets	410	524
Other Assets | Interest Rate Contract | Designated as Hedging Instrument
Derivatives, Fair Value [Line Items]
Total derivatives assets, net	308	500
Other Assets | Foreign Exchange Contract | Designated as Hedging Instrument
Derivatives, Fair Value [Line Items]
Total derivatives assets, net	102	24
Other Assets | Foreign Exchange Contract | Not Designated as Hedging Instrument
Derivatives, Fair Value [Line Items]
Total fair value of derivative assets	121	105
Other Liabilities
Derivatives, Fair Value [Line Items]
Total derivative liabilities, net	42	588
Cash collateral netting, liabilities	(3)	(16)
Other Liabilities | Designated as Hedging Instrument
Derivatives, Fair Value [Line Items]
Total fair value of derivative liabilities	47	474
Other Liabilities | Interest Rate Contract | Designated as Hedging Instrument
Derivatives, Fair Value [Line Items]
Total derivative liabilities, net	0	0
Other Liabilities | Foreign Exchange Contract | Designated as Hedging Instrument
Derivatives, Fair Value [Line Items]
Total derivative liabilities, net	47	474
Other Liabilities | Foreign Exchange Contract | Not Designated as Hedging Instrument
Derivatives, Fair Value [Line Items]
Total fair value of derivative liabilities	$ 72	$ 228