FINANCIAL INSTRUMENTS - Cash Flow Hedge Gains (Losses) in Accumulated Other Comprehensive Income (Details) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2017	Dec. 31, 2016
Disclosure of detailed information about hedges [line items]
Accumulated other comprehensive income, beginning balance	$ (189)
Effective portion of change in fair value of hedging instruments	(16)	$ 16
Realized (gains) losses on derivatives designated as cash flow hedges, net of tax ($9) and ($8)	23	64
Accumulated other comprehensive income, ending balance	(169)	(189)
Cash flow hedge
Disclosure of detailed information about hedges [line items]
Accumulated other comprehensive income, beginning balance	(43)	(140)
Effective portion of change in fair value of hedging instruments	(19)	25
Realized (gains) losses on derivatives designated as cash flow hedges, net of tax ($9) and ($8)	27	72
Accumulated other comprehensive income, ending balance	(30)	(43)
Hedge ineffectiveness due to changes in original forecasted transaction	5
Portion of hedge gain (loss) expected to affect 2017 earnings	(14)
Gold/Silver \| Cash flow hedge
Disclosure of detailed information about hedges [line items]
Accumulated other comprehensive income, beginning balance	9	14
Realized (gains) losses on derivatives designated as cash flow hedges, net of tax ($9) and ($8)	(7)	(5)
Accumulated other comprehensive income, ending balance	2	9
Portion of hedge gain (loss) expected to affect 2017 earnings	2
Copper \| Cash flow hedge
Disclosure of detailed information about hedges [line items]
Accumulated other comprehensive income, beginning balance	0
Effective portion of change in fair value of hedging instruments	(11)
Realized (gains) losses on derivatives designated as cash flow hedges, net of tax ($9) and ($8)	4
Accumulated other comprehensive income, ending balance	(7)	0
Portion of hedge gain (loss) expected to affect 2017 earnings	(7)
Fuel \| Cash flow hedge
Disclosure of detailed information about hedges [line items]
Accumulated other comprehensive income, beginning balance	(32)	(102)
Effective portion of change in fair value of hedging instruments	(8)	23
Realized (gains) losses on derivatives designated as cash flow hedges, net of tax ($9) and ($8)	27	47
Accumulated other comprehensive income, ending balance	(8)	(32)
Hedge ineffectiveness due to changes in original forecasted transaction	5
Fuel \| Cash flow hedge \| Operating costs
Disclosure of detailed information about hedges [line items]
Portion of hedge gain (loss) expected to affect 2017 earnings	(8)
Currency contracts \| Cash flow hedge \| Operating costs
Disclosure of detailed information about hedges [line items]
Accumulated other comprehensive income, beginning balance	0	(30)
Effective portion of change in fair value of hedging instruments		2
Realized (gains) losses on derivatives designated as cash flow hedges, net of tax ($9) and ($8)		28
Accumulated other comprehensive income, ending balance	0	0
Portion of hedge gain (loss) expected to affect 2017 earnings	0
Currency contracts \| Cash flow hedge \| General and administrative costs
Disclosure of detailed information about hedges [line items]
Accumulated other comprehensive income, beginning balance	0	0
Effective portion of change in fair value of hedging instruments		0
Realized (gains) losses on derivatives designated as cash flow hedges, net of tax ($9) and ($8)		0
Accumulated other comprehensive income, ending balance	0	0
Portion of hedge gain (loss) expected to affect 2017 earnings	0
Currency contracts \| Cash flow hedge \| Capital expenditures
Disclosure of detailed information about hedges [line items]
Accumulated other comprehensive income, beginning balance	0	0
Effective portion of change in fair value of hedging instruments		0
Realized (gains) losses on derivatives designated as cash flow hedges, net of tax ($9) and ($8)		0
Accumulated other comprehensive income, ending balance	0	0
Portion of hedge gain (loss) expected to affect 2017 earnings	0
Interest rate contracts \| Cash flow hedge
Disclosure of detailed information about hedges [line items]
Accumulated other comprehensive income, beginning balance	(20)	(22)
Effective portion of change in fair value of hedging instruments	0	0
Realized (gains) losses on derivatives designated as cash flow hedges, net of tax ($9) and ($8)	3	2
Accumulated other comprehensive income, ending balance	(17)	$ (20)
Portion of hedge gain (loss) expected to affect 2017 earnings	$ (1)

Estimated Reclassification Adjustments on Cash Flow Hedges, Next Fiscal Year

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- Definition

The amount of accumulated items of income and expense (including reclassification adjustments) that are not recognised in profit or loss as required or permitted by other IFRSs. [Refer: IFRSs [member]; Other comprehensive income]

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The gain (loss) recognised in other comprehensive income on hedge ineffectiveness. [Refer: Gain (loss) on hedge ineffectiveness]

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The gains (losses) recognised in other comprehensive income on cash flow hedges, net of tax. [Refer: Cash flow hedges [member]]

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The amount of reclassification adjustments related to cash flow hedges, net of tax. Reclassification adjustments are amounts reclassified to profit (loss) in the current period that were recognised in other comprehensive income in the current or previous periods. [Refer: Cash flow hedges [member]; Other comprehensive income]

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