Derivatives and Hedging Activities (Details) - USD ($) $ in Millions	Jun. 30, 2018	Dec. 31, 2017
Derivatives, Fair Value [Line Items]
Total fair value of derivative assets	$ 510	$ 210
Total fair value of derivative liabilities	279	218
Other Assets [Member]
Derivatives, Fair Value [Line Items]
Derivative asset and liability netting	(109)	(80)
Total derivatives assets, net	380	124
Cash collateral netting, Assets	(21)	(6)
Other Assets [Member] | Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Total derivatives assets, net	331	128
Other Assets [Member] | Interest Rate Contract [Member] | Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Total derivatives assets, net	0	11
Other Assets [Member] | Foreign exchange contracts [Member] | Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Total derivatives assets, net	331	117
Other Assets [Member] | Foreign exchange contracts [Member] | Not Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Total derivatives assets, net	179	82
Other Liabilities [Member]
Derivatives, Fair Value [Line Items]
Derivative asset and liability netting	(109)	(80)
Total derivative liabilities, net	43	93
Cash collateral netting, Liabilities	(127)	(45)
Other Liabilities [Member] | Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Total derivative liabilities, net	159	123
Other Liabilities [Member] | Interest Rate Contract [Member] | Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Total derivative liabilities, net	131	34
Other Liabilities [Member] | Foreign exchange contracts [Member] | Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Total derivative liabilities, net	28	89
Other Liabilities [Member] | Foreign exchange contracts [Member] | Not Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Total derivative liabilities, net	$ 120	95
Individually Significant Counterparties [Member]
Derivatives, Fair Value [Line Items]
Total derivatives assets, net		0
Total derivative liabilities, net		$ 0