Foreign currency risk - Narrative (Details) - CHF (SFr) SFr in Millions	12 Months Ended
Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Disclosure of Financial Risk Management [Abstract]
Net Derivative Financial Assets (Liabilities)	SFr 0.0	SFr 0.0
Change in fair value of foreign exchange derivatives	SFr 0.0	SFr 1.4	SFr (1.3)

The gains (losses) resulting from change in the fair value of derivatives recognised in profit or loss. [Refer: Derivatives [member]]

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Name IAS
-Number 1
-IssueDate 2022-03-24
-Paragraph 85
-URI https://taxonomy.ifrs.org/xifrs-link?type=IAS&num=1&code=ifrs-tx-2022-en-r&anchor=para_85&doctype=Standard
-URIDate 2022-03-24

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration