Taxation - Disclosure of reconciliation of items affected by overall tax credit (Details) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Disclosure of temporary difference, unused tax losses and unused tax credits [line items]
Profit before taxation	$ 8,154	$ 16,723	$ 7,180
Tax charge on profit	$ 3,964	$ 7,145	$ 3,712
Effective tax rate	49.00%	43.00%	52.00%
Tax rate computed at the weighted average statutory rate	52.00%	43.00%	44.00%
Increase (decrease) resulting from
Tax reported in equity-accounted entities	(0.07)	(0.05)	(0.07)
Deferred tax not recognizedb	(0.02)	0.01	0.06
Tax incentives for investment	(0.03)	(0.02)	(0.06)
Foreign exchange	1.00%	3.00%	(4.00%)
Items not deductible for tax purposes	4.00%	1.00%	5.00%
Impact of US tax reform	0.00%	(1.00%)	12.00%
Other	4.00%	3.00%	2.00%

Effective Income Tax Rate Reconciliation, Tax Cuts And Jobs Act Of 2017, Percent

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Increase (Decrease) Between Average Effective Rate And Applicable Tax Rate [Abstract]

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Tax Rate Effect From Deferred Tax Not Recognized

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Tax Rate Effect From Entities Accounted For Using Equity Method

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Tax Rate Effect Of Foreign Exchange Rates

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Tax Rate Effect Of Tax Incentives For Investment

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The applicable income tax rate.

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The tax expense (income) divided by the accounting profit. [Refer: Accounting profit]

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

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The aggregate amount included in the determination of profit (loss) for the period in respect of current tax and deferred tax. [Refer: Current tax expense (income); Deferred tax expense (income)]

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Tax rate effects, in aggregate, on the reconciliation between the average effective tax rate and the applicable tax rate that the entity does not separately disclose in the reconciliation. [Refer: Average effective tax rate; Applicable tax rate]

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The profit (loss) before tax expense or income. [Refer: Profit (loss)]

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The tax rate effect on the reconciliation between the average effective tax rate and the applicable tax rate resulting from the expenses not deductible in determining taxable profit. [Refer: Average effective tax rate; Applicable tax rate]

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