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Financial instruments and risk management - Summary of financial instruments carried at fair value (Detail) - USD ($) $ in Millions | Dec. 31, 2018 | Dec. 31, 2017
--- | --- | ---
Disclosure Of Financial Instruments [Line Items] |  |
Cash and cash equivalents | $ 10,773 | $ 10,550
Investments in equity shares and funds | 130 |
Equity shares and quoted funds | 130 | 136
Other investments, including loans | 2,782 | 1,152
Trade and other financial receivables | 3,007 | 2,985
Financial assets (excluding derivative assets) | 16,692 | 14,823
Forward contracts and option contracts: designated as hedges(f) (Section B) | 8 |
Forward contracts and option contracts, not designated as hedges | 334 | (87)
Derivatives related to net debt | (288) | (177)
Trade and other financial payables | (5,552) | (5,922)
Total | 11,194 | 8,637
Fair value [member] | Level 1 [member] |  |
Disclosure Of Financial Instruments [Line Items] |  |
Cash and cash equivalents | 7,994 |
Investments in equity shares and funds | 92 |
Equity shares and quoted funds |  | 88
Other investments, including loans | 2,544 | 1,037
Trade and other financial receivables | 20 |
Financial assets (excluding derivative assets) | 10,650 | 1,125
Total | 10,650 | 1,125
Fair value [member] | Level 2 [member] |  |
Disclosure Of Financial Instruments [Line Items] |  |
Trade and other financial receivables | 972 | 90
Financial assets (excluding derivative assets) | 972 | 90
Forward contracts and option contracts, not designated as hedges | (25) | 11
Derivatives related to net debt | (288) | (177)
Trade and other financial payables | (39) | (15)
Total | 620 | (91)
Fair value [member] | Level 3 [member] |  |
Disclosure Of Financial Instruments [Line Items] |  |
Investments in equity shares and funds | 38 |
Equity shares and quoted funds |  | 3
Other investments, including loans | 232 | 88
Financial assets (excluding derivative assets) | 270 | 91
Forward contracts and option contracts: designated as hedges(f) (Section B) | 8 |
Forward contracts and option contracts, not designated as hedges | 359 | (98)
Total | 637 | (7)
Not held at fair value [member] |  |
Disclosure Of Financial Instruments [Line Items] |  |
Cash and cash equivalents | 2,779 | 10,550
Equity shares and quoted funds |  | 45
Other investments, including loans | 6 | 27
Trade and other financial receivables | 2,015 | 2,895
Financial assets (excluding derivative assets) | 4,800 | 13,517
Trade and other financial payables | (5,513) | (5,907)
Total | $ (713) | $ 7,610

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- Definition The amount of cash on hand and demand deposits, along with short-term, highly liquid investments that are readily convertible to known amounts of cash and that are subject to an insignificant risk of changes in value. [Refer: Cash; Cash equivalents] + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Name IAS -Number 7 -IssueDate 2017-01-01 -Paragraph 45 -URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=7&date=2017-03-01&anchor=para_45&doctype=Standard -URIDate 2017-03-09 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Name IFRS -Number 12 -IssueDate 2017-01-01 -Paragraph B13 -Subparagraph a -URI http://eifrs.ifrs.org/eifrs/XBRL?type=IFRS&num=12&date=2017-03-01&anchor=para_B13_a&doctype=Appendix&seq=2 -URIDate 2017-03-09 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Name IAS -Number 1 -IssueDate 2017-01-01 -Paragraph 54 -Subparagraph i -URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=1&date=2017-03-01&anchor=para_54_i&doctype=Standard -URIDate 2017-03-09 + Details
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- Definition The fair value of financial instruments designated as hedging instruments. Hedging instruments are designated derivatives or (for a hedge of the risk of changes in foreign currency exchange rates only) designated non-derivative financial assets or non-derivative financial liabilities whose fair value or cash flows are expected to offset changes in the fair value or cash flows of a designated hedged item. [Refer: At fair value [member]; Derivatives [member]; Derivative financial assets; Derivative financial liabilities; Financial instruments, class [member]; Financial assets; Financial liabilities] + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Note Expiry date 2018-01-01 -Name IFRS -Number 7 -IssueDate 2017-01-01 -Paragraph 22 -Subparagraph b -URI http://eifrs.ifrs.org/eifrs/XBRL?type=IFRS&num=7&date=2017-03-02&anchor=para_22_b&doctype=Standard&book=B -URIDate 2017-03-09 + Details
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