Foreign currency risk - Financial assets and liabilities held in foreign currency (Details) € in Millions, SFr in Millions, $ in Millions	Dec. 31, 2024 CHF (SFr)	Dec. 31, 2024 USD ($)	Dec. 31, 2024 EUR (€)	Dec. 31, 2023 CHF (SFr)	Dec. 31, 2023 USD ($)	Dec. 31, 2023 EUR (€)
Disclosure of financial assets [line items]
Cash and cash equivalents	SFr 924.3	$ 629.3	€ 24.1	SFr 494.6	$ 248.7	€ 69.8
Trade Receivables And Other Financial Assets		229.6	34.5		640.0	102.1
Trade Payables And Other Financial Liabilities		(145.3)	(21.4)		(257.6)	(84.5)
Total assets and liabilities		$ 713.6	€ 37.2		$ 631.2	€ 87.4

The amount of cash on hand and demand deposits, along with short-term, highly liquid investments that are readily convertible to known amounts of cash and that are subject to an insignificant risk of changes in value. [Refer: Cash; Cash equivalents]

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IAS
-Number 7
-IssueDate 2024-01-01
-Paragraph 45
-URI https://taxonomy.ifrs.org/xifrs-link?type=IAS&num=7&code=ifrs-tx-2024-en-r&anchor=para_45&doctype=Standard
-URIDate 2024-03-27

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Name IFRS
-Number 12
-IssueDate 2024-01-01
-Paragraph B13
-Subparagraph a
-URI https://taxonomy.ifrs.org/xifrs-link?type=IFRS&num=12&code=ifrs-tx-2024-en-r&anchor=para_B13_a&doctype=Appendix&subtype=B
-URIDate 2024-03-27

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Name IAS
-Number 1
-IssueDate 2024-01-01
-Paragraph 54
-Subparagraph i
-URI https://taxonomy.ifrs.org/xifrs-link?type=IAS&num=1&code=ifrs-tx-2024-en-r&anchor=para_54_i&doctype=Standard
-URIDate 2024-03-27

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