v3.26.1
INTANGIBLE ASSETS (Details) - CAD ($)
$ in Millions
 12 Months Ended
Dec. 31, 2025
Dec. 31, 2024
Changes in the net carrying amount of intangible assets    
Balance at the beginning of the year $ 3,401.3  
Balance at the end of the year 3,375.2 $ 3,401.3
Intangible assets other than goodwill    
Changes in the net carrying amount of intangible assets    
Net of credits received on investment 29.1 36.6
(Decrease) increase in government credits receivable in large investment projects (28.0) 92.4
Spectrum licences    
Changes in the net carrying amount of intangible assets    
Balance at the beginning of the year 2,662.1  
Balance at the end of the year 2,662.1 2,662.1
spectrum licences and brand names    
Changes in the net carrying amount of intangible assets    
Intangible assets with indefinite useful life 2,760.9 2,760.9
Software    
Changes in the net carrying amount of intangible assets    
Balance at the beginning of the year 413.1  
Balance at the end of the year 454.2 413.1
Customer relationships, projects development and other    
Changes in the net carrying amount of intangible assets    
Balance at the beginning of the year 326.1  
Balance at the end of the year 258.9 326.1
Cost    
Changes in the net carrying amount of intangible assets    
Balance at the beginning of the year 5,026.9 4,727.0
Additions 127.3 418.5
Net change in additions financed with non-cash balances 34.5 (91.9)
Retirement, disposals and other (29.1) (26.7)
Balance at the end of the year 5,159.6 5,026.9
Cost | Spectrum licences    
Changes in the net carrying amount of intangible assets    
Balance at the beginning of the year 2,909.8 2,610.9
Additions   298.9
Balance at the end of the year 2,909.8 2,909.8
Cost | Software    
Changes in the net carrying amount of intangible assets    
Balance at the beginning of the year 1,713.9 1,752.1
Additions 69.1 28.1
Net change in additions financed with non-cash balances 34.5 (92.3)
Reclassification 96.4 52.7
Retirement, disposals and other (27.5) (26.7)
Balance at the end of the year 1,886.4 1,713.9
Cost | Customer relationships, projects development and other    
Changes in the net carrying amount of intangible assets    
Balance at the beginning of the year 403.2 364.0
Additions 58.2 91.5
Net change in additions financed with non-cash balances   0.4
Reclassification (96.4) (52.7)
Retirement, disposals and other (1.6)  
Balance at the end of the year 363.4 403.2
Accumulated amortization and impairment losses    
Changes in the net carrying amount of intangible assets    
Balance at the beginning of the year (1,625.6) (1,427.7)
Amortization (187.9) (224.6)
Retirement, disposals and other 29.1 26.7
Balance at the end of the year (1,784.4) (1,625.6)
Accumulated amortization and impairment losses | Spectrum licences    
Changes in the net carrying amount of intangible assets    
Balance at the beginning of the year (247.7) (247.7)
Balance at the end of the year (247.7) (247.7)
Accumulated amortization and impairment losses | Software    
Changes in the net carrying amount of intangible assets    
Balance at the beginning of the year (1,300.8) (1,139.5)
Amortization (158.9) (188.0)
Retirement, disposals and other 27.5 26.7
Balance at the end of the year (1,432.2) (1,300.8)
Accumulated amortization and impairment losses | Customer relationships, projects development and other    
Changes in the net carrying amount of intangible assets    
Balance at the beginning of the year (77.1) (40.5)
Amortization (29.0) (36.6)
Retirement, disposals and other 1.6  
Balance at the end of the year $ (104.5) $ (77.1)