DERIVATIVE FINANCIAL INSTRUMENTS - Narrative (Details) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Call option contracts
Disclosure of detailed information about hedging instruments [line items]
Fair value of derivative contracts	$ 12	$ 20
Put option contracts
Disclosure of detailed information about hedging instruments [line items]
Fair value of derivative contracts	$ 10	$ 11

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]

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

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Namespace Prefix:	ifrs-full_
Data Type:	xbrli:monetaryItemType
Balance Type:	na
Period Type:	instant