PROPERTY, PLANT AND EQUIPMENT - Summary of Property, Plant and Equipment (Details) - CHF (SFr)
SFr in Millions |
12 Months Ended |
Dec. 31, 2025 |
Dec. 31, 2024 |
| Reconciliation of changes in property, plant and equipment [abstract] |
|
|
| Property, plant and equipment at period start |
SFr 2,338.5
|
|
| Property, plant and equipment at period end |
2,231.6
|
SFr 2,338.5
|
| New Period Reclassification Adjustments |
|
|
| Reconciliation of changes in property, plant and equipment [abstract] |
|
|
| Property, plant and equipment at period start |
2,338.5
|
2,295.7
|
| Property, plant and equipment at period end |
|
2,338.5
|
| Network |
|
|
| Reconciliation of changes in property, plant and equipment [abstract] |
|
|
| Property, plant and equipment at period start |
1,514.9
|
|
| Property, plant and equipment at period end |
1,605.0
|
1,514.9
|
| Network | Prior Period Reclassification Adjustments | Distribution systems |
|
|
| Reconciliation of changes in property, plant and equipment [abstract] |
|
|
| Property, plant and equipment at period start |
427.8
|
681.7
|
| Property, plant and equipment at period end |
|
427.8
|
| Network | Prior Period Reclassification Adjustments | Customer premises equipment ('CPE') |
|
|
| Reconciliation of changes in property, plant and equipment [abstract] |
|
|
| Property, plant and equipment at period start |
44.0
|
39.5
|
| Property, plant and equipment at period end |
|
44.0
|
| Network | Prior Period Reclassification Adjustments | Support equipment and buildings |
|
|
| Reconciliation of changes in property, plant and equipment [abstract] |
|
|
| Property, plant and equipment at period start |
1,043.1
|
963.4
|
| Property, plant and equipment at period end |
|
1,043.1
|
| Network | Prior Period Reclassification Adjustments | Assets Under Construction |
|
|
| Reconciliation of changes in property, plant and equipment [abstract] |
|
|
| Property, plant and equipment at period start |
0.0
|
0.0
|
| Property, plant and equipment at period end |
|
0.0
|
| Network | New Period Reclassification Adjustments |
|
|
| Reconciliation of changes in property, plant and equipment [abstract] |
|
|
| Property, plant and equipment at period start |
1,514.9
|
1,684.6
|
| Property, plant and equipment at period end |
|
1,514.9
|
| Customer premises equipment ('CPE') |
|
|
| Reconciliation of changes in property, plant and equipment [abstract] |
|
|
| Property, plant and equipment at period start |
188.8
|
|
| Property, plant and equipment at period end |
224.7
|
188.8
|
| Customer premises equipment ('CPE') | Prior Period Reclassification Adjustments |
|
|
| Reconciliation of changes in property, plant and equipment [abstract] |
|
|
| Property, plant and equipment at period start |
232.8
|
208.3
|
| Property, plant and equipment at period end |
|
232.8
|
| Customer premises equipment ('CPE') | Prior Period Reclassification Adjustments | Distribution systems |
|
|
| Reconciliation of changes in property, plant and equipment [abstract] |
|
|
| Property, plant and equipment at period start |
0.0
|
0.0
|
| Property, plant and equipment at period end |
|
0.0
|
| Customer premises equipment ('CPE') | Prior Period Reclassification Adjustments | Customer premises equipment ('CPE') |
|
|
| Reconciliation of changes in property, plant and equipment [abstract] |
|
|
| Property, plant and equipment at period start |
188.8
|
168.8
|
| Property, plant and equipment at period end |
|
188.8
|
| Customer premises equipment ('CPE') | Prior Period Reclassification Adjustments | Support equipment and buildings |
|
|
| Reconciliation of changes in property, plant and equipment [abstract] |
|
|
| Property, plant and equipment at period start |
0.0
|
0.0
|
| Property, plant and equipment at period end |
|
0.0
|
| Customer premises equipment ('CPE') | Prior Period Reclassification Adjustments | Assets Under Construction |
|
|
| Reconciliation of changes in property, plant and equipment [abstract] |
|
|
| Property, plant and equipment at period start |
0.0
|
0.0
|
| Property, plant and equipment at period end |
|
0.0
|
| Customer premises equipment ('CPE') | New Period Reclassification Adjustments |
|
|
| Reconciliation of changes in property, plant and equipment [abstract] |
|
|
| Property, plant and equipment at period start |
188.8
|
168.8
|
| Property, plant and equipment at period end |
|
188.8
|
| Support Capital and Leasehold Improvement |
|
|
| Reconciliation of changes in property, plant and equipment [abstract] |
|
|
| Property, plant and equipment at period start |
108.3
|
|
| Property, plant and equipment at period end |
61.8
|
108.3
|
| Support Capital and Leasehold Improvement | Prior Period Reclassification Adjustments | Distribution systems |
|
|
| Reconciliation of changes in property, plant and equipment [abstract] |
|
|
| Property, plant and equipment at period start |
0.0
|
0.0
|
| Property, plant and equipment at period end |
|
0.0
|
| Support Capital and Leasehold Improvement | Prior Period Reclassification Adjustments | Customer premises equipment ('CPE') |
|
|
| Reconciliation of changes in property, plant and equipment [abstract] |
|
|
| Property, plant and equipment at period start |
0.0
|
0.0
|
| Property, plant and equipment at period end |
|
0.0
|
| Support Capital and Leasehold Improvement | Prior Period Reclassification Adjustments | Support equipment and buildings |
|
|
| Reconciliation of changes in property, plant and equipment [abstract] |
|
|
| Property, plant and equipment at period start |
108.3
|
84.2
|
| Property, plant and equipment at period end |
|
108.3
|
| Support Capital and Leasehold Improvement | Prior Period Reclassification Adjustments | Assets Under Construction |
|
|
| Reconciliation of changes in property, plant and equipment [abstract] |
|
|
| Property, plant and equipment at period start |
0.0
|
0.0
|
| Property, plant and equipment at period end |
|
0.0
|
| Support Capital and Leasehold Improvement | New Period Reclassification Adjustments |
|
|
| Reconciliation of changes in property, plant and equipment [abstract] |
|
|
| Property, plant and equipment at period start |
108.3
|
84.2
|
| Property, plant and equipment at period end |
|
108.3
|
| Land and Buildings |
|
|
| Reconciliation of changes in property, plant and equipment [abstract] |
|
|
| Property, plant and equipment at period start |
6.8
|
|
| Property, plant and equipment at period end |
5.9
|
6.8
|
| Land and Buildings | Prior Period Reclassification Adjustments | Distribution systems |
|
|
| Reconciliation of changes in property, plant and equipment [abstract] |
|
|
| Property, plant and equipment at period start |
0.0
|
0.0
|
| Property, plant and equipment at period end |
|
0.0
|
| Land and Buildings | Prior Period Reclassification Adjustments | Customer premises equipment ('CPE') |
|
|
| Reconciliation of changes in property, plant and equipment [abstract] |
|
|
| Property, plant and equipment at period start |
0.0
|
0.0
|
| Property, plant and equipment at period end |
|
0.0
|
| Land and Buildings | Prior Period Reclassification Adjustments | Support equipment and buildings |
|
|
| Reconciliation of changes in property, plant and equipment [abstract] |
|
|
| Property, plant and equipment at period start |
6.8
|
10.6
|
| Property, plant and equipment at period end |
|
6.8
|
| Land and Buildings | Prior Period Reclassification Adjustments | Assets Under Construction |
|
|
| Reconciliation of changes in property, plant and equipment [abstract] |
|
|
| Property, plant and equipment at period start |
0.0
|
0.0
|
| Property, plant and equipment at period end |
|
0.0
|
| Land and Buildings | New Period Reclassification Adjustments |
|
|
| Reconciliation of changes in property, plant and equipment [abstract] |
|
|
| Property, plant and equipment at period start |
6.8
|
10.6
|
| Property, plant and equipment at period end |
|
6.8
|
| Assets Under Construction |
|
|
| Reconciliation of changes in property, plant and equipment [abstract] |
|
|
| Property, plant and equipment at period start |
519.7
|
|
| Property, plant and equipment at period end |
334.2
|
519.7
|
| Assets Under Construction | Prior Period Reclassification Adjustments |
|
|
| Reconciliation of changes in property, plant and equipment [abstract] |
|
|
| Property, plant and equipment at period start |
519.7
|
347.5
|
| Property, plant and equipment at period end |
|
519.7
|
| Assets Under Construction | Prior Period Reclassification Adjustments | Distribution systems |
|
|
| Reconciliation of changes in property, plant and equipment [abstract] |
|
|
| Property, plant and equipment at period start |
0.0
|
0.0
|
| Property, plant and equipment at period end |
|
0.0
|
| Assets Under Construction | Prior Period Reclassification Adjustments | Customer premises equipment ('CPE') |
|
|
| Reconciliation of changes in property, plant and equipment [abstract] |
|
|
| Property, plant and equipment at period start |
0.0
|
0.0
|
| Property, plant and equipment at period end |
|
0.0
|
| Assets Under Construction | Prior Period Reclassification Adjustments | Support equipment and buildings |
|
|
| Reconciliation of changes in property, plant and equipment [abstract] |
|
|
| Property, plant and equipment at period start |
0.0
|
0.0
|
| Property, plant and equipment at period end |
|
0.0
|
| Assets Under Construction | Prior Period Reclassification Adjustments | Assets Under Construction |
|
|
| Reconciliation of changes in property, plant and equipment [abstract] |
|
|
| Property, plant and equipment at period start |
519.7
|
347.5
|
| Property, plant and equipment at period end |
|
519.7
|
| Assets Under Construction | New Period Reclassification Adjustments |
|
|
| Reconciliation of changes in property, plant and equipment [abstract] |
|
|
| Property, plant and equipment at period start |
519.7
|
347.5
|
| Property, plant and equipment at period end |
|
519.7
|
| Distribution systems | Prior Period Reclassification Adjustments |
|
|
| Reconciliation of changes in property, plant and equipment [abstract] |
|
|
| Property, plant and equipment at period start |
427.8
|
681.7
|
| Property, plant and equipment at period end |
|
427.8
|
| Support equipment and buildings | Prior Period Reclassification Adjustments |
|
|
| Reconciliation of changes in property, plant and equipment [abstract] |
|
|
| Property, plant and equipment at period start |
1,158.2
|
1,058.2
|
| Property, plant and equipment at period end |
|
1,158.2
|
| Cost |
|
|
| Reconciliation of changes in property, plant and equipment [abstract] |
|
|
| Property, plant and equipment at period start |
5,587.6
|
5,596.4
|
| Additions |
395.6
|
408.0
|
| Retirements and disposals |
(118.7)
|
(339.4)
|
| Reclassifications |
(56.7)
|
(76.4)
|
| Other |
(0.7)
|
(1.0)
|
| Property, plant and equipment at period end |
5,807.1
|
5,587.6
|
| Cost | Network |
|
|
| Reconciliation of changes in property, plant and equipment [abstract] |
|
|
| Property, plant and equipment at period start |
4,527.4
|
4,722.6
|
| Additions |
289.9
|
291.3
|
| Retirements and disposals |
(78.5)
|
(211.9)
|
| Reclassifications |
124.9
|
(274.6)
|
| Other |
0.1
|
0.0
|
| Property, plant and equipment at period end |
4,863.8
|
4,527.4
|
| Cost | Customer premises equipment ('CPE') |
|
|
| Reconciliation of changes in property, plant and equipment [abstract] |
|
|
| Property, plant and equipment at period start |
315.4
|
328.7
|
| Additions |
87.4
|
88.9
|
| Retirements and disposals |
(13.9)
|
(101.3)
|
| Reclassifications |
3.5
|
(0.9)
|
| Other |
0.0
|
0.0
|
| Property, plant and equipment at period end |
392.4
|
315.4
|
| Cost | Support Capital and Leasehold Improvement |
|
|
| Reconciliation of changes in property, plant and equipment [abstract] |
|
|
| Property, plant and equipment at period start |
200.2
|
167.5
|
| Additions |
15.4
|
27.8
|
| Retirements and disposals |
(25.6)
|
(20.9)
|
| Reclassifications |
(0.3)
|
25.8
|
| Other |
(0.1)
|
0.0
|
| Property, plant and equipment at period end |
189.6
|
200.2
|
| Cost | Land and Buildings |
|
|
| Reconciliation of changes in property, plant and equipment [abstract] |
|
|
| Property, plant and equipment at period start |
25.0
|
30.1
|
| Additions |
2.9
|
0.0
|
| Retirements and disposals |
(0.7)
|
(5.3)
|
| Reclassifications |
0.0
|
0.1
|
| Other |
0.0
|
0.0
|
| Property, plant and equipment at period end |
27.1
|
25.0
|
| Cost | Assets Under Construction |
|
|
| Reconciliation of changes in property, plant and equipment [abstract] |
|
|
| Property, plant and equipment at period start |
519.7
|
347.5
|
| Additions |
0.0
|
0.0
|
| Retirements and disposals |
0.0
|
0.0
|
| Reclassifications |
(184.8)
|
173.2
|
| Other |
(0.7)
|
(1.0)
|
| Property, plant and equipment at period end |
334.2
|
519.7
|
| Accumulated depreciation and impairment |
|
|
| Reconciliation of changes in property, plant and equipment [abstract] |
|
|
| Property, plant and equipment at period start |
(3,249.1)
|
(3,300.6)
|
| Depreciation |
(417.6)
|
(368.0)
|
| Retirements and disposals |
117.1
|
339.0
|
| Reclassifications |
(25.8)
|
65.5
|
| Other |
0.0
|
15.0
|
| Property, plant and equipment at period end |
(3,575.5)
|
(3,249.1)
|
| Accumulated depreciation and impairment | Network |
|
|
| Reconciliation of changes in property, plant and equipment [abstract] |
|
|
| Property, plant and equipment at period start |
(3,012.5)
|
(3,037.9)
|
| Depreciation |
(297.6)
|
(269.2)
|
| Retirements and disposals |
78.1
|
211.4
|
| Reclassifications |
(26.8)
|
68.2
|
| Other |
0.0
|
15.0
|
| Property, plant and equipment at period end |
(3,258.8)
|
(3,012.5)
|
| Accumulated depreciation and impairment | Customer premises equipment ('CPE') |
|
|
| Reconciliation of changes in property, plant and equipment [abstract] |
|
|
| Property, plant and equipment at period start |
(126.6)
|
(159.9)
|
| Depreciation |
(58.4)
|
(65.1)
|
| Retirements and disposals |
12.8
|
101.3
|
| Reclassifications |
4.5
|
(2.9)
|
| Other |
0.0
|
0.0
|
| Property, plant and equipment at period end |
(167.7)
|
(126.6)
|
| Accumulated depreciation and impairment | Support Capital and Leasehold Improvement |
|
|
| Reconciliation of changes in property, plant and equipment [abstract] |
|
|
| Property, plant and equipment at period start |
(91.9)
|
(83.3)
|
| Depreciation |
(58.0)
|
(29.8)
|
| Retirements and disposals |
25.6
|
21.0
|
| Reclassifications |
(3.5)
|
0.2
|
| Other |
0.0
|
0.0
|
| Property, plant and equipment at period end |
(127.8)
|
(91.9)
|
| Accumulated depreciation and impairment | Land and Buildings |
|
|
| Reconciliation of changes in property, plant and equipment [abstract] |
|
|
| Property, plant and equipment at period start |
(18.2)
|
(19.5)
|
| Depreciation |
(3.6)
|
(3.9)
|
| Retirements and disposals |
0.6
|
5.3
|
| Reclassifications |
0.0
|
0.0
|
| Other |
0.0
|
0.0
|
| Property, plant and equipment at period end |
SFr (21.2)
|
SFr (18.2)
|