v3.26.1
INVESTMENT IN EQUITY ACCOUNTED INVESTEES - Reconciliation of equity accounted investments (Details) - CAD ($)
$ in Millions
 12 Months Ended
Mar. 31, 2026
Mar. 31, 2025
Disclosure of joint ventures [line items]    
Investments accounted for using equity method $ 559.1  
Investments accounted for using equity method 572.7 $ 559.1
Aggregated individually immaterial joint ventures    
Disclosure of joint ventures [line items]    
Investments accounted for using equity method 559.1 588.8
Non-cash contributions to equity accounted investees   13.0
Cash contributions to equity accounted investees 14.5  
Share of after-tax profit before elimination of unrealized profits 86.9 96.2
Elimination of unrealized profits on transactions with equity accounted investees – net (4.2) (7.8)
Dividends received from equity accounted investees (79.6) (28.7)
Dividends declared but not yet received from equity accounted investees   (7.2)
Transfers and others 7.4 0.7
Foreign currency exchange differences (11.4) 35.1
Investments accounted for using equity method $ 572.7 559.1
SIMCOM    
Disclosure of joint ventures [line items]    
Acquisition of control of SIMCOM (Note $2)   $ (131.0)