v3.24.0.1
Income taxes - Tax Rate Reconciliation (Details) - CHF (SFr)
SFr in Millions
12 Months Ended
Dec. 31, 2023
Dec. 31, 2022
Dec. 31, 2021
Disclosure of temporary difference, unused tax losses and unused tax credits [line items]      
Income / (loss) before taxes SFr 69.1 SFr 77.9 SFr (159.6)
Expected tax rate 19.70% 19.70% 19.70%
Expected tax expense SFr 13.6 SFr 15.3 SFr (31.4)
Non-deductible expenses 10.30% 9.20% (25.40%)
Non-deductible expenses SFr 7.1 SFr 7.2 SFr 40.6
Income not subject to tax (22.40%) (9.50%) (0.20%)
Income not subject to tax SFr (15.5) SFr (7.4)  
Effects of (de-)recognition of tax losses (2.40%) 2.90% (0.40%)
Effects of (de-)recognition of tax losses SFr (1.7) SFr 2.2 SFr 0.6
Local actual tax rate different to On's expected average tax rate (1.10%) 2.00% (0.60%)
Local actual tax rate different to On's expected average tax rate SFr (0.8) SFr 1.5 SFr 1.0
Prior year adjustments and other items, net (19.20%) 1.60% 0.20%
Prior year adjustments and other items, net SFr (13.3) SFr 1.3 SFr (0.3)
Effective tax rate (15.10%) 25.90% (6.70%)
Income tax expense (benefit) SFr (10.5) SFr 20.2 SFr 10.6
Income not subject to tax, netting      
Disclosure of temporary difference, unused tax losses and unused tax credits [line items]      
Income not subject to tax     SFr 0.3