Derivative Instruments and Hedging Activities (Fair Value Amounts of Derivative Instruments Reported on our Condensed Consolidated Balance Sheet) (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Derivatives, Fair Value [Line Items]
Derivative contracts in a receivable position, fair value	$ 41	$ 39
Fair value of derivative contracts in a payable position	37	41
Derivative, notional amount	38,066	23,762
Designated as hedging instrument
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	1
Derivative, notional amount	24,339	7,051
Not designated as hedging instrument \| Other trading
Derivatives, Fair Value [Line Items]
Derivative contracts in a receivable position, fair value	40	39
Fair value of derivative contracts in a payable position	37	40
Derivative, notional amount	13,727	16,711
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	24,203	6,915
Foreign exchange forwards \| Designated as hedging instrument
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	1
Derivative, notional amount	136	136
Interest rate contracts \| Not designated as hedging instrument
Derivatives, Fair Value [Line Items]
Derivative contracts in a receivable position, fair value	37	39
Fair value of derivative contracts in a payable position	37	39
Derivative, notional amount	13,546	16,587
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	23
Interest rate contracts \| Not designated as hedging instrument \| Written options
Derivatives, Fair Value [Line Items]
Derivative contracts in a receivable position, fair value	0	1
Fair value of derivative contracts in a payable position	37	39
Derivative, notional amount	6,793	8,327
Interest rate contracts \| Not designated as hedging instrument \| Purchased options
Derivatives, Fair Value [Line Items]
Derivative contracts in a receivable position, fair value	37	38
Fair value of derivative contracts in a payable position	0	0
Derivative, notional amount	6,742	8,237
Foreign exchange contracts \| Not designated as hedging instrument
Derivatives, Fair Value [Line Items]
Derivative contracts in a receivable position, fair value	3	0
Fair value of derivative contracts in a payable position	0	1
Derivative, notional amount	181	124
Foreign exchange contracts \| Not designated as hedging instrument \| Foreign exchange forwards
Derivatives, Fair Value [Line Items]
Derivative contracts in a receivable position, fair value	3	0
Fair value of derivative contracts in a payable position	0	1
Derivative, notional amount	$ 181	$ 124

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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