EMPLOYEE POST-RETIREMENT BENEFITS - Measured at Fair Value (Details) - CAD ($) $ in Millions | Dec. 31, 2024 | Dec. 31, 2023 | Dec. 31, 2022 |
Employee post-retirement benefits | | | |
Fair value of plan assets | $ 4,397 | $ 4,055 | |
Percentage of Plan Assets | 100% | 100% | |
Pension Benefit Plans | | | |
Employee post-retirement benefits | | | |
Fair value of plan assets | $ 3,948 | $ 3,697 | $ 3,481 |
Percentage of Plan Assets | 100% | 100% | |
Quoted Prices in Active Markets (Level I) | | | |
Employee post-retirement benefits | | | |
Fair value of plan assets | $ 2,324 | $ 2,057 | |
Significant Other Observable Inputs (Level II) | | | |
Employee post-retirement benefits | | | |
Fair value of plan assets | 1,483 | 1,436 | |
Significant Unobservable Inputs (Level III) | | | |
Employee post-retirement benefits | | | |
Fair value of plan assets | 590 | 562 | $ 632 |
Cash and Cash Equivalents | | | |
Employee post-retirement benefits | | | |
Fair value of plan assets | $ 138 | $ 69 | |
Percentage of Plan Assets | 3% | 2% | |
Cash and Cash Equivalents | Quoted Prices in Active Markets (Level I) | | | |
Employee post-retirement benefits | | | |
Fair value of plan assets | $ 138 | $ 68 | |
Cash and Cash Equivalents | Significant Other Observable Inputs (Level II) | | | |
Employee post-retirement benefits | | | |
Fair value of plan assets | 0 | 1 | |
Cash and Cash Equivalents | Significant Unobservable Inputs (Level III) | | | |
Employee post-retirement benefits | | | |
Fair value of plan assets | 0 | 0 | |
Equity Securities, Canadian | | | |
Employee post-retirement benefits | | | |
Fair value of plan assets | $ 128 | $ 121 | |
Percentage of Plan Assets | 3% | 3% | |
Equity Securities, Canadian | Quoted Prices in Active Markets (Level I) | | | |
Employee post-retirement benefits | | | |
Fair value of plan assets | $ 128 | $ 121 | |
Equity Securities, Canadian | Significant Other Observable Inputs (Level II) | | | |
Employee post-retirement benefits | | | |
Fair value of plan assets | 0 | 0 | |
Equity Securities, Canadian | Significant Unobservable Inputs (Level III) | | | |
Employee post-retirement benefits | | | |
Fair value of plan assets | 0 | 0 | |
Equity Securities, U.S. | | | |
Employee post-retirement benefits | | | |
Fair value of plan assets | $ 1,234 | $ 965 | |
Percentage of Plan Assets | 28% | 24% | |
Equity Securities, U.S. | Quoted Prices in Active Markets (Level I) | | | |
Employee post-retirement benefits | | | |
Fair value of plan assets | $ 1,234 | $ 965 | |
Equity Securities, U.S. | Significant Other Observable Inputs (Level II) | | | |
Employee post-retirement benefits | | | |
Fair value of plan assets | 0 | 0 | |
Equity Securities, U.S. | Significant Unobservable Inputs (Level III) | | | |
Employee post-retirement benefits | | | |
Fair value of plan assets | 0 | 0 | |
Equity Securities, International | | | |
Employee post-retirement benefits | | | |
Fair value of plan assets | $ 391 | $ 354 | |
Percentage of Plan Assets | 9% | 9% | |
Equity Securities, International | Quoted Prices in Active Markets (Level I) | | | |
Employee post-retirement benefits | | | |
Fair value of plan assets | $ 182 | $ 167 | |
Equity Securities, International | Significant Other Observable Inputs (Level II) | | | |
Employee post-retirement benefits | | | |
Fair value of plan assets | 209 | 187 | |
Equity Securities, International | Significant Unobservable Inputs (Level III) | | | |
Employee post-retirement benefits | | | |
Fair value of plan assets | 0 | 0 | |
Equity Securities, Global | | | |
Employee post-retirement benefits | | | |
Fair value of plan assets | $ 100 | $ 74 | |
Percentage of Plan Assets | 2% | 2% | |
Equity Securities, Global | Quoted Prices in Active Markets (Level I) | | | |
Employee post-retirement benefits | | | |
Fair value of plan assets | $ 0 | $ 0 | |
Equity Securities, Global | Significant Other Observable Inputs (Level II) | | | |
Employee post-retirement benefits | | | |
Fair value of plan assets | 100 | 74 | |
Equity Securities, Global | Significant Unobservable Inputs (Level III) | | | |
Employee post-retirement benefits | | | |
Fair value of plan assets | 0 | 0 | |
Equity Securities, Emerging | | | |
Employee post-retirement benefits | | | |
Fair value of plan assets | $ 216 | $ 194 | |
Percentage of Plan Assets | 5% | 5% | |
Equity Securities, Emerging | Quoted Prices in Active Markets (Level I) | | | |
Employee post-retirement benefits | | | |
Fair value of plan assets | $ 66 | $ 54 | |
Equity Securities, Emerging | Significant Other Observable Inputs (Level II) | | | |
Employee post-retirement benefits | | | |
Fair value of plan assets | 150 | 140 | |
Equity Securities, Emerging | Significant Unobservable Inputs (Level III) | | | |
Employee post-retirement benefits | | | |
Fair value of plan assets | 0 | 0 | |
Fixed Income Securities, Canadian Bonds, Federal | | | |
Employee post-retirement benefits | | | |
Fair value of plan assets | $ 55 | $ 266 | |
Percentage of Plan Assets | 1% | 7% | |
Fixed Income Securities, Canadian Bonds, Federal | Quoted Prices in Active Markets (Level I) | | | |
Employee post-retirement benefits | | | |
Fair value of plan assets | $ 0 | $ 0 | |
Fixed Income Securities, Canadian Bonds, Federal | Significant Other Observable Inputs (Level II) | | | |
Employee post-retirement benefits | | | |
Fair value of plan assets | 55 | 266 | |
Fixed Income Securities, Canadian Bonds, Federal | Significant Unobservable Inputs (Level III) | | | |
Employee post-retirement benefits | | | |
Fair value of plan assets | 0 | 0 | |
Fixed Income Securities, Canadian Bonds, Provincial | | | |
Employee post-retirement benefits | | | |
Fair value of plan assets | $ 312 | $ 314 | |
Percentage of Plan Assets | 7% | 8% | |
Fixed Income Securities, Canadian Bonds, Provincial | Quoted Prices in Active Markets (Level I) | | | |
Employee post-retirement benefits | | | |
Fair value of plan assets | $ 0 | $ 0 | |
Fixed Income Securities, Canadian Bonds, Provincial | Significant Other Observable Inputs (Level II) | | | |
Employee post-retirement benefits | | | |
Fair value of plan assets | 312 | 314 | |
Fixed Income Securities, Canadian Bonds, Provincial | Significant Unobservable Inputs (Level III) | | | |
Employee post-retirement benefits | | | |
Fair value of plan assets | 0 | 0 | |
Fixed Income Securities, Canadian Bonds, Municipal | | | |
Employee post-retirement benefits | | | |
Fair value of plan assets | $ 14 | $ 16 | |
Percentage of Plan Assets | 0% | 0% | |
Fixed Income Securities, Canadian Bonds, Municipal | Quoted Prices in Active Markets (Level I) | | | |
Employee post-retirement benefits | | | |
Fair value of plan assets | $ 0 | $ 0 | |
Fixed Income Securities, Canadian Bonds, Municipal | Significant Other Observable Inputs (Level II) | | | |
Employee post-retirement benefits | | | |
Fair value of plan assets | 14 | 16 | |
Fixed Income Securities, Canadian Bonds, Municipal | Significant Unobservable Inputs (Level III) | | | |
Employee post-retirement benefits | | | |
Fair value of plan assets | 0 | 0 | |
Fixed Income Securities, Canadian Bonds, Corporate | | | |
Employee post-retirement benefits | | | |
Fair value of plan assets | $ 323 | $ 143 | |
Percentage of Plan Assets | 7% | 4% | |
Fixed Income Securities, Canadian Bonds, Corporate | Quoted Prices in Active Markets (Level I) | | | |
Employee post-retirement benefits | | | |
Fair value of plan assets | $ 0 | $ 0 | |
Fixed Income Securities, Canadian Bonds, Corporate | Significant Other Observable Inputs (Level II) | | | |
Employee post-retirement benefits | | | |
Fair value of plan assets | 323 | 143 | |
Fixed Income Securities, Canadian Bonds, Corporate | Significant Unobservable Inputs (Level III) | | | |
Employee post-retirement benefits | | | |
Fair value of plan assets | 0 | 0 | |
Fixed Income Securities, U.S. Bonds, Federal | | | |
Employee post-retirement benefits | | | |
Fair value of plan assets | $ 406 | $ 425 | |
Percentage of Plan Assets | 9% | 10% | |
Fixed Income Securities, U.S. Bonds, Federal | Quoted Prices in Active Markets (Level I) | | | |
Employee post-retirement benefits | | | |
Fair value of plan assets | $ 151 | $ 185 | |
Fixed Income Securities, U.S. Bonds, Federal | Significant Other Observable Inputs (Level II) | | | |
Employee post-retirement benefits | | | |
Fair value of plan assets | 255 | 240 | |
Fixed Income Securities, U.S. Bonds, Federal | Significant Unobservable Inputs (Level III) | | | |
Employee post-retirement benefits | | | |
Fair value of plan assets | 0 | 0 | |
Fixed Income Securities, U.S. Bonds, Municipal | | | |
Employee post-retirement benefits | | | |
Fair value of plan assets | $ 1 | $ 1 | |
Percentage of Plan Assets | 0% | 0% | |
Fixed Income Securities, U.S. Bonds, Municipal | Quoted Prices in Active Markets (Level I) | | | |
Employee post-retirement benefits | | | |
Fair value of plan assets | $ 0 | $ 0 | |
Fixed Income Securities, U.S. Bonds, Municipal | Significant Other Observable Inputs (Level II) | | | |
Employee post-retirement benefits | | | |
Fair value of plan assets | 1 | 1 | |
Fixed Income Securities, U.S. Bonds, Municipal | Significant Unobservable Inputs (Level III) | | | |
Employee post-retirement benefits | | | |
Fair value of plan assets | 0 | 0 | |
Fixed Income Securities, U.S. Bonds, Corporate | | | |
Employee post-retirement benefits | | | |
Fair value of plan assets | $ 404 | $ 386 | |
Percentage of Plan Assets | 9% | 10% | |
Fixed Income Securities, U.S. Bonds, Corporate | Quoted Prices in Active Markets (Level I) | | | |
Employee post-retirement benefits | | | |
Fair value of plan assets | $ 246 | $ 312 | |
Fixed Income Securities, U.S. Bonds, Corporate | Significant Other Observable Inputs (Level II) | | | |
Employee post-retirement benefits | | | |
Fair value of plan assets | 158 | 74 | |
Fixed Income Securities, U.S. Bonds, Corporate | Significant Unobservable Inputs (Level III) | | | |
Employee post-retirement benefits | | | |
Fair value of plan assets | 0 | 0 | |
Fixed Income Securities, International, Government | | | |
Employee post-retirement benefits | | | |
Fair value of plan assets | $ 21 | $ 15 | |
Percentage of Plan Assets | 1% | 0% | |
Fixed Income Securities, International, Government | Quoted Prices in Active Markets (Level I) | | | |
Employee post-retirement benefits | | | |
Fair value of plan assets | $ 4 | $ 4 | |
Fixed Income Securities, International, Government | Significant Other Observable Inputs (Level II) | | | |
Employee post-retirement benefits | | | |
Fair value of plan assets | 17 | 11 | |
Fixed Income Securities, International, Government | Significant Unobservable Inputs (Level III) | | | |
Employee post-retirement benefits | | | |
Fair value of plan assets | 0 | 0 | |
Fixed Income Securities, International, Corporate | | | |
Employee post-retirement benefits | | | |
Fair value of plan assets | $ 66 | $ 83 | |
Percentage of Plan Assets | 2% | 2% | |
Fixed Income Securities, International, Corporate | Quoted Prices in Active Markets (Level I) | | | |
Employee post-retirement benefits | | | |
Fair value of plan assets | $ 0 | $ 0 | |
Fixed Income Securities, International, Corporate | Significant Other Observable Inputs (Level II) | | | |
Employee post-retirement benefits | | | |
Fair value of plan assets | 66 | 83 | |
Fixed Income Securities, International, Corporate | Significant Unobservable Inputs (Level III) | | | |
Employee post-retirement benefits | | | |
Fair value of plan assets | 0 | 0 | |
Fixed Income Securities, International, Mortgage-backed | | | |
Employee post-retirement benefits | | | |
Fair value of plan assets | $ 60 | $ 60 | |
Percentage of Plan Assets | 1% | 1% | |
Fixed Income Securities, International, Mortgage-backed | Quoted Prices in Active Markets (Level I) | | | |
Employee post-retirement benefits | | | |
Fair value of plan assets | $ 37 | $ 43 | |
Fixed Income Securities, International, Mortgage-backed | Significant Other Observable Inputs (Level II) | | | |
Employee post-retirement benefits | | | |
Fair value of plan assets | 23 | 17 | |
Fixed Income Securities, International, Mortgage-backed | Significant Unobservable Inputs (Level III) | | | |
Employee post-retirement benefits | | | |
Fair value of plan assets | 0 | 0 | |
Net Forward Contract, International | | | |
Employee post-retirement benefits | | | |
Fair value of plan assets | $ (201) | $ (131) | |
Percentage of Plan Assets | 4% | 4% | |
Net Forward Contract, International | Quoted Prices in Active Markets (Level I) | | | |
Employee post-retirement benefits | | | |
Fair value of plan assets | $ 0 | $ 0 | |
Net Forward Contract, International | Significant Other Observable Inputs (Level II) | | | |
Employee post-retirement benefits | | | |
Fair value of plan assets | (201) | (131) | |
Net Forward Contract, International | Significant Unobservable Inputs (Level III) | | | |
Employee post-retirement benefits | | | |
Fair value of plan assets | 0 | 0 | |
Real estate | | | |
Employee post-retirement benefits | | | |
Fair value of plan assets | $ 276 | $ 283 | |
Percentage of Plan Assets | 6% | 7% | |
Real estate | Quoted Prices in Active Markets (Level I) | | | |
Employee post-retirement benefits | | | |
Fair value of plan assets | $ 0 | $ 0 | |
Real estate | Significant Other Observable Inputs (Level II) | | | |
Employee post-retirement benefits | | | |
Fair value of plan assets | 0 | 0 | |
Real estate | Significant Unobservable Inputs (Level III) | | | |
Employee post-retirement benefits | | | |
Fair value of plan assets | 276 | 283 | |
Infrastructure | | | |
Employee post-retirement benefits | | | |
Fair value of plan assets | $ 282 | $ 269 | |
Percentage of Plan Assets | 7% | 7% | |
Infrastructure | Quoted Prices in Active Markets (Level I) | | | |
Employee post-retirement benefits | | | |
Fair value of plan assets | $ 0 | $ 0 | |
Infrastructure | Significant Other Observable Inputs (Level II) | | | |
Employee post-retirement benefits | | | |
Fair value of plan assets | 0 | 0 | |
Infrastructure | Significant Unobservable Inputs (Level III) | | | |
Employee post-retirement benefits | | | |
Fair value of plan assets | 282 | 269 | |
Private equity funds | | | |
Employee post-retirement benefits | | | |
Fair value of plan assets | $ 32 | $ 10 | |
Percentage of Plan Assets | 1% | 0% | |
Private equity funds | Quoted Prices in Active Markets (Level I) | | | |
Employee post-retirement benefits | | | |
Fair value of plan assets | $ 0 | $ 0 | |
Private equity funds | Significant Other Observable Inputs (Level II) | | | |
Employee post-retirement benefits | | | |
Fair value of plan assets | 0 | 0 | |
Private equity funds | Significant Unobservable Inputs (Level III) | | | |
Employee post-retirement benefits | | | |
Fair value of plan assets | 32 | 10 | |
Funds held on deposit | | | |
Employee post-retirement benefits | | | |
Fair value of plan assets | $ 138 | $ 138 | |
Percentage of Plan Assets | 3% | 3% | |
Funds held on deposit | Quoted Prices in Active Markets (Level I) | | | |
Employee post-retirement benefits | | | |
Fair value of plan assets | $ 138 | $ 138 | |
Funds held on deposit | Significant Other Observable Inputs (Level II) | | | |
Employee post-retirement benefits | | | |
Fair value of plan assets | 0 | 0 | |
Funds held on deposit | Significant Unobservable Inputs (Level III) | | | |
Employee post-retirement benefits | | | |
Fair value of plan assets | 0 | 0 | |
Derivatives | | | |
Employee post-retirement benefits | | | |
Fair value of plan assets | $ 1 | $ 0 | |
Percentage of Plan Assets | 0% | 0% | |
Derivatives | Quoted Prices in Active Markets (Level I) | | | |
Employee post-retirement benefits | | | |
Fair value of plan assets | $ 0 | $ 0 | |
Derivatives | Significant Other Observable Inputs (Level II) | | | |
Employee post-retirement benefits | | | |
Fair value of plan assets | 1 | 0 | |
Derivatives | Significant Unobservable Inputs (Level III) | | | |
Employee post-retirement benefits | | | |
Fair value of plan assets | $ 0 | $ 0 | |