Investment in associate - Narrative (Details) - t t in Millions	12 Months Ended
Dec. 31, 2025	Dec. 31, 2024
Atlas Methanol Company Unlimited
Disclosure of associates [line items]
Annual methanol production facility owned (in tonnes)	1.8
Term of expired natural gas agreement	20 years
Interest %	100.00%
Firewater
Disclosure of associates [line items]
Annual methanol production facility owned (in tonnes)	1.7
Interest %	100.00%
Atlas Methanol Company Unlimited
Disclosure of associates [line items]
Percentage of ownership interest in associates	63.10%	63.10%
Firewater
Disclosure of associates [line items]
Percentage of ownership interest in associates	50.00%	0.00%

The proportion of ownership interest in an associate attributable to the entity. [Refer: Total for all associates [member]]

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IAS
-Number 27
-IssueDate 2025-01-01
-Paragraph 17
-Subparagraph b
-Clause iii
-URI https://taxonomy.ifrs.org/xifrs-link?type=IAS&num=27&code=ifrs-tx-2025-en-r&anchor=para_17_b_iii&doctype=Standard
-URIDate 2025-03-27

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Name IAS
-Number 27
-IssueDate 2025-01-01
-Paragraph 16
-Subparagraph b
-Clause iii
-URI https://taxonomy.ifrs.org/xifrs-link?type=IAS&num=27&code=ifrs-tx-2025-en-r&anchor=para_16_b_iii&doctype=Standard
-URIDate 2025-03-27

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Name IFRS
-Number 12
-IssueDate 2025-01-01
-Paragraph 21
-Subparagraph a
-Clause iv
-URI https://taxonomy.ifrs.org/xifrs-link?type=IFRS&num=12&code=ifrs-tx-2025-en-r&anchor=para_21_a_iv&doctype=Standard
-URIDate 2025-03-27

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Namespace Prefix:	ifrs-full_
Data Type:	dtr-2022:percentItemType
Balance Type:	na
Period Type:	duration