Mining Interests - Owned By Subsidiaries - Summary of Carrying Amount of Mining Interests by Property Owned by Subsidiaries (Parenthetical) (Detail) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2017	Dec. 31, 2016
Disclosure of mining assets and property, plant and equipment [Abstract]
Assets not yet ready for intended use	$ 512	$ 309
Finance lease included in plant and equipment	278	299
Royalties included in production cost	$ 78	$ 69

The amount of assets recognised by the entity, which are leased under finance leases.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Note Expiry date 2019-01-01
-Name IAS
-Number 17
-IssueDate 2017-01-01
-Paragraph 31
-Subparagraph a
-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=17&date=2017-03-02&anchor=para_31_a&doctype=Standard&book=B
-URIDate 2017-03-09

Name:	ifrs-full_RecognisedFinanceLeaseAsAssets
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant