Non-current assets held for sale (Details)		6 Months Ended
Jul. 03, 2018	Dec. 31, 2018
Clair
Disclosure of joint ventures [line items]
Ownership percentage in joint operations		45.10%
Ownership percentage in joint operations acquired		16.50%
Greater Kuparuk Area
Disclosure of joint ventures [line items]
Ownership percentage in joint operations	39.20%

The proportion of ownership interest in a joint operation attributable to the entity. [Refer: Joint operations [member]]

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IFRS
-Number 12
-IssueDate 2017-01-01
-Paragraph 21
-Subparagraph a
-Clause iv
-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IFRS&num=12&date=2017-03-01&anchor=para_21_a_iv&doctype=Standard
-URIDate 2017-03-09

Name:	ifrs-full_ProportionOfOwnershipInterestInJointOperation
Namespace Prefix:	ifrs-full_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration