Derivative instruments (Hedged Liabilities and Cumulative Amount) (Details) - USD ($) $ in Millions	Mar. 31, 2020	Dec. 31, 2019
Derivative [Line Items]
Cumulative amounts of fair value hedging adjustments related to the carrying amounts of the hedged liabilities	$ 648	$ 296
Current portion of long-term debt [Member]
Derivative [Line Items]
Hedged Liability, Fair Value Hedge	90	903
Cumulative amounts of fair value hedging adjustments related to the carrying amounts of the hedged liabilities	90	4
Carrying value with discontinued hedging relationships	90
Hedging adjustments on discontinued hedging relationships	90
Long-term debt [Member]
Derivative [Line Items]
Hedged Liability, Fair Value Hedge	7,784	8,814
Cumulative amounts of fair value hedging adjustments related to the carrying amounts of the hedged liabilities	558	292
Carrying value with discontinued hedging relationships	592	136
Hedging adjustments on discontinued hedging relationships	$ 492	$ 36

Hedged Liability, Discontinued Fair Value Hedge

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- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

+ 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, remaining after discontinued hedge.

+ 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 (d)
-URI http://asc.fasb.org/extlink&oid=109980867&loc=SL109999712-113959

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- 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

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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

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