Additional disclosure items G.4. Non-cash investing and financing activity (Details) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Additional information [abstract]
Acquisition of property, plant and equipment, including (finance) leases	$ 17	$ (65)	$ (174)
Asset retirement obligations	19	15	(20)
Acquisition of subsidiaries, joint ventures and associates, net of cash acquired	0	30	0
(Finance) Leases	1	(43)	192
Share based compensation	$ 27	$ 21	$ 22

The increase in liabilities arising from financing activities resulting from new leases. [Refer: Liabilities arising from financing activities]

Reference 1: http://www.xbrl.org/2003/role/exampleRef
-Name IAS
-Number 7
-IssueDate 2019-01-01
-Section A Statement of cash flows for an entity other than a financial institution
-URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IAS&num=7&code=ifrs-tx-2019-en-r&doctype=Illustrative%20Examples&dita_xref=IAS07_IE_A_TI
-URIDate 2019-03-27

Reference 2: http://www.xbrl.org/2003/role/exampleRef
-Name IAS
-Number 7
-IssueDate 2019-01-01
-Paragraph 44B
-URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IAS&num=7&code=ifrs-tx-2019-en-r&anchor=para_44B&doctype=Standard
-URIDate 2019-03-27

Name:	ifrs-full_IncreaseThroughNewLeasesLiabilitiesArisingFromFinancingActivities
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration