EMPLOYEE POST-RETIREMENT BENEFITS - Measured at Fair Value (Details) - CAD ($) $ in Millions | Dec. 31, 2023 | Dec. 31, 2022 | Dec. 31, 2021 |
Employee post-retirement benefits | | | |
Fair value of plan assets | $ 4,055 | $ 3,835 | |
Percentage of Total Portfolio | 100% | 100% | |
Quoted Prices in Active Markets (Level I) | | | |
Employee post-retirement benefits | | | |
Fair value of plan assets | $ 2,057 | $ 1,998 | |
Significant Other Observable Inputs (Level II) | | | |
Employee post-retirement benefits | | | |
Fair value of plan assets | 1,436 | 1,205 | |
Significant Unobservable Inputs (Level III) | | | |
Employee post-retirement benefits | | | |
Fair value of plan assets | 562 | 632 | $ 565 |
Cash and Cash Equivalents | | | |
Employee post-retirement benefits | | | |
Fair value of plan assets | $ 69 | $ 56 | |
Percentage of Total Portfolio | 2% | 1% | |
Cash and Cash Equivalents | Quoted Prices in Active Markets (Level I) | | | |
Employee post-retirement benefits | | | |
Fair value of plan assets | $ 68 | $ 55 | |
Cash and Cash Equivalents | Significant Other Observable Inputs (Level II) | | | |
Employee post-retirement benefits | | | |
Fair value of plan assets | 1 | 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 | $ 121 | $ 117 | |
Percentage of Total Portfolio | 3% | 3% | |
Equity Securities, Canadian | Quoted Prices in Active Markets (Level I) | | | |
Employee post-retirement benefits | | | |
Fair value of plan assets | $ 121 | $ 117 | |
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 | $ 965 | $ 897 | |
Percentage of Total Portfolio | 24% | 24% | |
Equity Securities, U.S. | Quoted Prices in Active Markets (Level I) | | | |
Employee post-retirement benefits | | | |
Fair value of plan assets | $ 965 | $ 897 | |
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 | $ 354 | $ 344 | |
Percentage of Total Portfolio | 9% | 9% | |
Equity Securities, International | Quoted Prices in Active Markets (Level I) | | | |
Employee post-retirement benefits | | | |
Fair value of plan assets | $ 167 | $ 172 | |
Equity Securities, International | Significant Other Observable Inputs (Level II) | | | |
Employee post-retirement benefits | | | |
Fair value of plan assets | 187 | 172 | |
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 | $ 74 | $ 75 | |
Percentage of Total Portfolio | 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 | 74 | 75 | |
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 | $ 194 | $ 177 | |
Percentage of Total Portfolio | 5% | 5% | |
Equity Securities, Emerging | Quoted Prices in Active Markets (Level I) | | | |
Employee post-retirement benefits | | | |
Fair value of plan assets | $ 54 | $ 50 | |
Equity Securities, Emerging | Significant Other Observable Inputs (Level II) | | | |
Employee post-retirement benefits | | | |
Fair value of plan assets | 140 | 127 | |
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 | $ 266 | $ 221 | |
Percentage of Total Portfolio | 7% | 6% | |
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 | 266 | 221 | |
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 | $ 314 | $ 249 | |
Percentage of Total Portfolio | 8% | 6% | |
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 | 314 | 249 | |
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 | $ 16 | $ 12 | |
Percentage of Total Portfolio | 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 | 16 | 12 | |
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 | $ 143 | $ 108 | |
Percentage of Total Portfolio | 4% | 3% | |
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 | 143 | 108 | |
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 | $ 425 | $ 335 | |
Percentage of Total Portfolio | 10% | 9% | |
Fixed Income Securities, U.S. Bonds, Federal | Quoted Prices in Active Markets (Level I) | | | |
Employee post-retirement benefits | | | |
Fair value of plan assets | $ 185 | $ 177 | |
Fixed Income Securities, U.S. Bonds, Federal | Significant Other Observable Inputs (Level II) | | | |
Employee post-retirement benefits | | | |
Fair value of plan assets | 240 | 158 | |
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 Total Portfolio | 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 | $ 386 | $ 439 | |
Percentage of Total Portfolio | 10% | 11% | |
Fixed Income Securities, U.S. Bonds, Corporate | Quoted Prices in Active Markets (Level I) | | | |
Employee post-retirement benefits | | | |
Fair value of plan assets | $ 312 | $ 345 | |
Fixed Income Securities, U.S. Bonds, Corporate | Significant Other Observable Inputs (Level II) | | | |
Employee post-retirement benefits | | | |
Fair value of plan assets | 74 | 94 | |
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 | $ 15 | $ 11 | |
Percentage of Total Portfolio | 0% | 0% | |
Fixed Income Securities, International, Government | Quoted Prices in Active Markets (Level I) | | | |
Employee post-retirement benefits | | | |
Fair value of plan assets | $ 4 | $ 5 | |
Fixed Income Securities, International, Government | Significant Other Observable Inputs (Level II) | | | |
Employee post-retirement benefits | | | |
Fair value of plan assets | 11 | 6 | |
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 | $ 83 | $ 58 | |
Percentage of Total Portfolio | 2% | 1% | |
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 | 83 | 58 | |
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 | $ 37 | |
Percentage of Total Portfolio | 1% | 1% | |
Fixed Income Securities, International, Mortgage-backed | Quoted Prices in Active Markets (Level I) | | | |
Employee post-retirement benefits | | | |
Fair value of plan assets | $ 43 | $ 36 | |
Fixed Income Securities, International, Mortgage-backed | Significant Other Observable Inputs (Level II) | | | |
Employee post-retirement benefits | | | |
Fair value of plan assets | 17 | 1 | |
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 | $ (131) | $ (78) | |
Percentage of Total Portfolio | (4.00%) | (2.00%) | |
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 | (131) | (78) | |
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 | $ 283 | $ 336 | |
Percentage of Total Portfolio | 7% | 9% | |
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 | 283 | 336 | |
Infrastructure | | | |
Employee post-retirement benefits | | | |
Fair value of plan assets | $ 269 | $ 296 | |
Percentage of Total Portfolio | 7% | 8% | |
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 | 269 | 296 | |
Private equity funds | | | |
Employee post-retirement benefits | | | |
Fair value of plan assets | $ 10 | $ 0 | |
Percentage of Total Portfolio | 0% | 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 | 10 | 0 | |
Funds held on deposit | | | |
Employee post-retirement benefits | | | |
Fair value of plan assets | $ 138 | $ 144 | |
Percentage of Total Portfolio | 3% | 4% | |
Funds held on deposit | Quoted Prices in Active Markets (Level I) | | | |
Employee post-retirement benefits | | | |
Fair value of plan assets | $ 138 | $ 144 | |
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 | |