Derivatives and Hedging Activities (Details) - USD ($) $ in Millions	Jun. 30, 2019	Dec. 31, 2018
Derivatives, Fair Value [Line Items]
Total fair value of derivative assets	$ 460	$ 514
Total fair value of derivative liabilities	210	214
Other Assets [Member]
Derivatives, Fair Value [Line Items]
Derivative asset and liability netting	(133)	(90)
Total derivatives assets, net	136	396
Cash collateral netting, Assets	(191)	(28)
Other Assets [Member] | Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Total fair value of derivative assets	298	256
Other Assets [Member] | Interest Rate Contract [Member] | Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Total derivatives assets, net	191	34
Other Assets [Member] | Foreign Exchange Contract [Member] | Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Total derivatives assets, net	107	222
Other Assets [Member] | Foreign Exchange Contract [Member] | Not Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Total fair value of derivative assets	162	258
Other Liabilities [Member]
Derivatives, Fair Value [Line Items]
Derivative asset and liability netting	(133)	(90)
Total derivative liabilities, net	68	46
Cash collateral netting, Liabilities	(9)	(78)
Other Liabilities [Member] | Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Total fair value of derivative liabilities	60	135
Other Liabilities [Member] | Interest Rate Contract [Member] | Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Total derivative liabilities, net	0	74
Other Liabilities [Member] | Foreign Exchange Contract [Member] | Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Total derivative liabilities, net	60	61
Other Liabilities [Member] | Foreign Exchange Contract [Member] | Not Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Total fair value of derivative liabilities	$ 150	$ 79