Derivative Financial Instruments - Schedule of Differences Between the Gains (Losses) on the Derivative and The Gains (Losses) on the Hedged Item (Details) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Derivative [Line Items]
Gain (loss) on derivative recognized in OCI, cash flow hedge	$ 51	$ (24)	$ (118)
Gain (loss) on derivative recognized in OCI, net investment hedge	30	81	(160)
Amount of Gain or (Loss) Recognized in Other Comprehensive Income on Derivative	81	57	(278)
Gain (loss) on hedges reclassified to income, cash flow hedge	17	26	26
Gain (loss) on hedges reclassified to income, net investment hedge	0	0	0
Amount of Gain or (Loss) Reclassified from Accumulated Other Comprehensive Income into Income	17	26	26
Interest rate contracts
Derivative [Line Items]
Gain (loss) on derivative recognized in OCI, cash flow hedge	8	(12)	(14)
Interest rate contracts \| Net interest revenue
Derivative [Line Items]
Gain (loss) on hedges reclassified to income, cash flow hedge	(10)	(1)	2
Foreign exchange contracts
Derivative [Line Items]
Gain (loss) on derivative recognized in OCI, cash flow hedge	43	(12)	(104)
Gain (loss) on derivative recognized in OCI, net investment hedge	30	81	(160)
Foreign exchange contracts \| Net interest revenue
Derivative [Line Items]
Gain (loss) on hedges reclassified to income, cash flow hedge	27	27	24
Foreign exchange contracts \| Gains (Losses) related to investment securities, net
Derivative [Line Items]
Gain (loss) on hedges reclassified to income, net investment hedge	$ 0	$ 0	$ 0

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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.

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Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 20
-Section 45
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Amount, before tax, of reclassification of gain (loss) from accumulated other comprehensive income (AOCI) for derivative instrument designated and qualifying as cash flow hedge included in assessment of hedge effectiveness.

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Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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