RELATED-PARTY TRANSACTIONS - Additional Information (Details) - CHF (SFr) SFr in Millions |
12 Months Ended | ||
|---|---|---|---|
Dec. 31, 2025 |
Dec. 31, 2024 |
Dec. 31, 2023 |
|
| Related Party [Abstract] | |||
| Net advances from (to) related parties | SFr (0.2) | SFr 112.7 | SFr (204.8) |