Derivative Instruments and Hedging Activities (Derivative Instruments Used in Net Investment Hedge Accounting Relationships) (Details) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Derivative Instruments, Gain (Loss) [Line Items]
Gain (loss) recognized in other comprehensive income (loss), net investment hedge, foreign exchange contracts	$ (3)	$ 3	$ (5)	$ 7
Interest rate contracts \| Cash flow hedging
Derivative Instruments, Gain (Loss) [Line Items]
Gain (loss) recognized in other comprehensive income (loss), cash flow hedge, interest rate contracts	22	5	12	23
Foreign exchange contracts \| Net investment hedging
Derivative Instruments, Gain (Loss) [Line Items]
Gain (loss) recognized in other comprehensive income (loss), net investment hedge, foreign exchange contracts	(3)	3	(5)	7
Derivative, Excluded Component, Gain (Loss), Recognized in Earnings	0	0	0	0
Other Comprehensive Income (Loss), Net Investment Hedge, Gain (Loss), Reclassification, before Tax	$ 0	$ 0	$ 0	$ 0

Amount of gain (loss) from excluded component of derivative hedge, recognized in earnings. Excludes recognition under systematic and rational method.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 20
-Section 45
-Paragraph 1A
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-URI http://asc.fasb.org/extlink&oid=109974929&loc=SL110061172-113977

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Amount, before tax and reclassification, of gain (loss) from derivative instrument designated and qualifying cash flow hedge included in assessment of hedge effectiveness.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
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-SubTopic 20
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Reference 3: http://www.xbrl.org/2003/role/disclosureRef
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Amount, before tax and reclassification, of gain (loss) from derivative designated and qualifying as net investment hedge.

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Amount, before tax, of reclassification from accumulated other comprehensive income (AOCI) for gain (loss) from derivative designated and qualifying as net investment hedge.

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