GOODWILL - Reconciliation of Changes in Goodwill (Details) - CHF (SFr) SFr in Millions |
12 Months Ended | |
|---|---|---|
Dec. 31, 2025 |
Dec. 31, 2024 |
|
| Reconciliation of changes in intangible assets and goodwill [abstract] | ||
| Goodwill at beginning of period | SFr 6,012.7 | SFr 6,012.7 |
| Additions from business combinations | 0.0 | 0.0 |
| Goodwill at end of period | 6,012.7 | 6,012.7 |
| Residential | ||
| Reconciliation of changes in intangible assets and goodwill [abstract] | ||
| Goodwill at beginning of period | 4,587.1 | 4,587.1 |
| Additions from business combinations | 0.0 | 0.0 |
| Goodwill at end of period | 4,587.1 | 4,587.1 |
| Business | ||
| Reconciliation of changes in intangible assets and goodwill [abstract] | ||
| Goodwill at beginning of period | 1,098.3 | 1,098.3 |
| Additions from business combinations | 0.0 | 0.0 |
| Goodwill at end of period | 1,098.3 | 1,098.3 |
| Wholesale | ||
| Reconciliation of changes in intangible assets and goodwill [abstract] | ||
| Goodwill at beginning of period | 327.3 | 327.3 |
| Additions from business combinations | 0.0 | 0.0 |
| Goodwill at end of period | SFr 327.3 | SFr 327.3 |