REVENUE FROM CONTRACTS WITH CUSTOMERS - Contract Liabilities (Details) - CHF (SFr) SFr in Millions |
Dec. 31, 2025 |
Dec. 31, 2024 |
Dec. 31, 2023 |
|---|---|---|---|
| Disclosure of disaggregation of revenue from contracts with customers [line items] | |||
| Total | SFr 69.5 | SFr 74.9 | SFr 79.8 |
| Thereof current portion of contract liabilities | 66.2 | 71.3 | 66.7 |
| Thereof non-current portion of contract liabilities | 3.3 | 3.5 | 13.1 |
| Residential customers | |||
| Disclosure of disaggregation of revenue from contracts with customers [line items] | |||
| Total | 38.8 | 46.1 | 43.1 |
| Business customers & Wholesale | |||
| Disclosure of disaggregation of revenue from contracts with customers [line items] | |||
| Total | 30.6 | 28.0 | 36.3 |
| Infrastructure & Support functions | |||
| Disclosure of disaggregation of revenue from contracts with customers [line items] | |||
| Total | SFr 0.1 | SFr 0.8 | SFr 0.5 |