LEASING - Lease Expenses (Details) - CHF (SFr) SFr in Millions |
12 Months Ended | ||
|---|---|---|---|
Dec. 31, 2025 |
Dec. 31, 2024 |
Dec. 31, 2023 |
|
| Disclosure of quantitative information about right-of-use assets [line items] | |||
| Total depreciation and amortisation | SFr 129.9 | SFr 129.7 | SFr 128.0 |
| Interest expense | 61.3 | 69.8 | 67.9 |
| Short-term lease expense | 3.1 | 2.4 | 3.2 |
| Total lease expense | 194.3 | 201.9 | 199.1 |
| Network | |||
| Disclosure of quantitative information about right-of-use assets [line items] | |||
| Total depreciation and amortisation | 94.0 | 101.4 | 99.3 |
| Land, buildings and other | |||
| Disclosure of quantitative information about right-of-use assets [line items] | |||
| Total depreciation and amortisation | SFr 35.9 | SFr 28.3 | SFr 28.7 |