Derivative Financial Instruments - Cumulative Basis Adjustments for Fair Value Hedges (Details) - USD ($) $ in Millions	Mar. 31, 2020	Dec. 31, 2019
Short-term debt
Amounts recorded in the Consolidated Statement of Financial Position related to cumulative basis adjustments for fair value hedges
Carrying amount of the hedged item	$ (1,314)
Cumulative hedging adjustments included in the carrying amount-assets/(liabilities)	(15)
Long-term debt
Amounts recorded in the Consolidated Statement of Financial Position related to cumulative basis adjustments for fair value hedges
Carrying amount of the hedged item	(2,147)	$ (3,411)
Cumulative hedging adjustments included in the carrying amount-assets/(liabilities)	(475)	(440)
Hedging adjustments on discontinued hedging relationships	$ (391)	$ (404)

Amount of cumulative increase (decrease) in fair value of hedged liability in fair value hedge, attributable to hedged risk, remaining after discontinued hedge.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 4EE
-Subparagraph (d)
-URI http://asc.fasb.org/extlink&oid=109980867&loc=SL109999712-113959

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount of liability hedged in fair value hedging relationship.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 4EE
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=109980867&loc=SL109999712-113959

+ Details

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- Definition

Amount of cumulative increase (decrease) in fair value of hedged liability in fair value hedge, attributable to hedged risk.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 4EE
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=109980867&loc=SL109999712-113959

+ Details

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- References

No definition available.

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