v3.25.4
SEGMENT REPORTING - Segment Information (Details) - CHF (SFr)
SFr in Millions
 12 Months Ended
Dec. 31, 2025
Dec. 31, 2024
Dec. 31, 2023
Disclosure of operating segments [line items]      
Total revenue SFr 2,983.4 SFr 3,018.0 SFr 3,035.2
Direct costs (831.2) (830.1) (834.6)
Indirect costs (954.2) (966.4) (961.1)
Lease expense (191.1) (199.4) (195.9)
Adj. EBITDA after lease expense (EBITDAaL) 1,006.9 1,022.1 1,043.6
Depreciation and amortisation of property, plant and equipment and intangible assets (936.4) (917.9) (992.1)
Share-based compensation (49.0) (19.1) (22.5)
Restructuring & other 13.5 (49.8) (86.2)
Finance income/(expense) (163.4) (413.8) (315.0)
Income tax benefit 19.9 16.7 59.9
Net (loss) (108.5) (361.9) (312.2)
Unadjusted Difference      
Disclosure of operating segments [line items]      
Restructuring & other   (49.9) (86.1)
Residential Customers      
Disclosure of operating segments [line items]      
Total revenue 2,107.2 2,173.1 2,247.1
Direct costs (508.2) (515.2) (537.6)
Indirect costs (392.1) (401.5) (417.5)
Lease expense (50.7) (52.0) (51.0)
Adj. EBITDA after lease expense (EBITDAaL) 1,156.2 1,204.4 1,241.0
Residential Customers | Unadjusted Difference      
Disclosure of operating segments [line items]      
Total revenue     2,247.1
Business Customers & Wholesale      
Disclosure of operating segments [line items]      
Total revenue 859.0 830.3 776.6
Direct costs (305.9) (299.5) (271.0)
Indirect costs (114.2) (115.8) (115.4)
Lease expense (12.7) (13.5) (11.2)
Adj. EBITDA after lease expense (EBITDAaL) 426.2 401.5 379.0
Business Customers & Wholesale | Unadjusted Difference      
Disclosure of operating segments [line items]      
Total revenue     776.6
Infrastructure & Support Functions      
Disclosure of operating segments [line items]      
Total revenue 17.2 14.6 11.5
Direct costs (17.1) (15.4) (26.0)
Indirect costs (447.9) (449.1) (428.2)
Lease expense (127.7) (133.9) (133.7)
Adj. EBITDA after lease expense (EBITDAaL) SFr (575.5) SFr (583.8) SFr (576.4)