Commitments and contingencies - Capital commitments and contingencies (Details) - CHF (SFr)	Dec. 31, 2019	Dec. 31, 2018
Commitments and contingencies
Contracted capital expenditure	SFr 0	SFr 0
Outstanding litigation	SFr 0

The amount of the estimated financial effect of contingent liabilities. [Refer: Contingent liabilities [member]]

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IAS
-Number 37
-IssueDate 2019-01-01
-Paragraph 86
-Subparagraph a
-URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IAS&num=37&code=ifrs-tx-2019-en-r&anchor=para_86_a&doctype=Standard
-URIDate 2019-03-27

Name:	ifrs-full_EstimatedFinancialEffectOfContingentLiabilities
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant