Business combinations and other significant transactions - Summary of fair values of identifiable assets and liabilities acquired (Details) - USD ($) $ in Millions	Dec. 31, 2018	Oct. 31, 2018
Assets
Cash and cash equivalents recognised as of acquisition date	$ 114
Petrohawk Energy Corporation
Assets
Property, plant and equipment		$ 10,845
Intangible assets		21
Inventories		27
Trade and other receivables		493
Cash and cash equivalents recognised as of acquisition date		104
Liabilities
Trade and other payables		(659)
Provisions		(323)
Non-controlling interest		(206)
Total consideration		$ 10,302

Business Combination, Recognized Identifiable Assets Acquired And Liabilities Assumed, Assets 1 [Abstract]

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Business Combination, Recognized Identifiable Assets Acquired And Liabilities Assumed, Liabilities [Abstract]

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Provisions Recognized As Of The Acquisition Date

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Trade And Other Receivables Recognised As Of Acquisition Date

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The amount recognised as of the acquisition date for cash and cash equivalents acquired in a business combination. [Refer: Cash and cash equivalents; Business combinations [member]]

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The amount recognised as of the acquisition date for net identifiable assets acquired or liabilities assumed in a business combination. [Refer: Business combinations [member]]

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The amount recognised as of the acquisition date for identifiable intangible assets acquired in a business combination. [Refer: Intangible assets other than goodwill; Business combinations [member]]

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The amount recognised as of the acquisition date for inventory acquired in a business combination. [Refer: Inventories; Business combinations [member]]

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The amount of non-controlling interest in the acquiree recognised at the acquisition date for business combinations in which the acquirer holds less than 100 per cent of the equity interests in the acquiree at the acquisition date. [Refer: Business combinations [member]]

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Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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The amount recognised as of the acquisition date for plant, property and equipment acquired in a business combination. [Refer: Property, plant and equipment; Business combinations [member]]

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The amount recognised as of the acquisition date for trade and other payables assumed in a business combination. [Refer: Trade and other payables; Business combinations [member]]

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