Derivative Instruments and Hedging Activities (Fair Value Amounts of Derivative Instruments Reported on our Condensed Consolidated Balance Sheet) (Details) - USD ($) $ in Millions	Mar. 31, 2019	Dec. 31, 2018
Derivatives, Fair Value [Line Items]
Derivative contracts in a receivable position, fair value	$ 22	$ 41
Fair value of derivative contracts in a payable position	21	37
Derivative, notional amount	24,716	38,066
Designated as hedging instrument
Derivatives, Fair Value [Line Items]
Derivative contracts in a receivable position, fair value	1	1
Fair value of derivative contracts in a payable position	1	0
Derivative, notional amount	12,319	24,339
Not designated as hedging instrument \| Other trading
Derivatives, Fair Value [Line Items]
Derivative contracts in a receivable position, fair value	21	40
Fair value of derivative contracts in a payable position	20	37
Derivative, notional amount	12,397	13,727
Interest rate swaps \| Designated as hedging instrument
Derivatives, Fair Value [Line Items]
Derivative contracts in a receivable position, fair value	0	0
Fair value of derivative contracts in a payable position	0	0
Derivative, notional amount	12,085	24,203
Foreign exchange forwards \| Designated as hedging instrument
Derivatives, Fair Value [Line Items]
Derivative contracts in a receivable position, fair value	0	1
Fair value of derivative contracts in a payable position	1	0
Derivative, notional amount	134	136
Interest rate contracts \| Designated as hedging instrument \| Purchased options
Derivatives, Fair Value [Line Items]
Derivative contracts in a receivable position, fair value	1	0
Fair value of derivative contracts in a payable position	0	0
Derivative, notional amount	100	0
Interest rate contracts \| Not designated as hedging instrument
Derivatives, Fair Value [Line Items]
Derivative contracts in a receivable position, fair value	21	37
Fair value of derivative contracts in a payable position	19	37
Derivative, notional amount	12,272	13,546
Interest rate contracts \| Not designated as hedging instrument \| Futures and forwards
Derivatives, Fair Value [Line Items]
Derivative contracts in a receivable position, fair value	0	0
Fair value of derivative contracts in a payable position	0	0
Derivative, notional amount	11	11
Interest rate contracts \| Not designated as hedging instrument \| Written options
Derivatives, Fair Value [Line Items]
Derivative contracts in a receivable position, fair value	2	0
Fair value of derivative contracts in a payable position	19	37
Derivative, notional amount	6,180	6,793
Interest rate contracts \| Not designated as hedging instrument \| Purchased options
Derivatives, Fair Value [Line Items]
Derivative contracts in a receivable position, fair value	19	37
Fair value of derivative contracts in a payable position	0	0
Derivative, notional amount	6,081	6,742
Foreign exchange contracts \| Not designated as hedging instrument
Derivatives, Fair Value [Line Items]
Derivative contracts in a receivable position, fair value	0	3
Fair value of derivative contracts in a payable position	0	0
Derivative, notional amount	124	181
Foreign exchange contracts \| Not designated as hedging instrument \| Futures and forwards
Derivatives, Fair Value [Line Items]
Derivative contracts in a receivable position, fair value	0	3
Fair value of derivative contracts in a payable position	0	0
Derivative, notional amount	124	181
Equity contract \| Not designated as hedging instrument
Derivatives, Fair Value [Line Items]
Derivative contracts in a receivable position, fair value	0	0
Fair value of derivative contracts in a payable position	1	0
Derivative, notional amount	1	0
Equity contract \| Not designated as hedging instrument \| Written options
Derivatives, Fair Value [Line Items]
Derivative contracts in a receivable position, fair value	0	0
Fair value of derivative contracts in a payable position	1	0
Derivative, notional amount	$ 1	$ 0

Aggregate notional amount specified by the derivative(s). Expressed as an absolute value.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Article 12
-Section 13
-Sentence Column B

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