Financial liabilities - Schedule of Assets Pledged in Relation to Credit Facility (Details) - CHF (SFr) SFr in Millions	Jun. 30, 2026	Dec. 31, 2025
Disclosure of financial liabilities [abstract]
Trade receivables	SFr 312.8	SFr 266.4
Inventory	342.2	340.4
Assets pledged	SFr 655.1	SFr 606.9

The amount of inventories pledged as security for liabilities. [Refer: Inventories]

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IAS
-Number 2
-IssueDate 2025-01-01
-Paragraph 36
-Subparagraph h
-URI https://taxonomy.ifrs.org/xifrs-link?type=IAS&num=2&code=ifrs-tx-2025-en-r&anchor=para_36_h&doctype=Standard
-URIDate 2025-03-27

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Note Effective 2027-01-01
-Name IFRS
-Number 19
-IssueDate 2025-01-01
-Paragraph 164
-Subparagraph f
-URI https://taxonomy.ifrs.org/xifrs-link?type=IFRS&num=19&code=ifrs-tx-2025-en-r&anchor=para_164_f&doctype=Standard
-URIDate 2025-03-27

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Note Effective 2027-01-01
-Name IFRS
-Number 19
-IssueDate 2025-01-01
-Paragraph 164
-Subparagraph f
-URI https://taxonomy.ifrs.org/xifrs-link?type=IFRS&num=19&code=ifrs-tx-2025-en-r&anchor=para_164_f&doctype=Standard
-URIDate 2025-03-27

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