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Revenue - Disaggregation of Revenue (Details) - CAD ($) $ in Millions | 12 Months Ended
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Dec. 31, 2024 | Dec. 31, 2023 | Dec. 31, 2022
Disclosure of disaggregation of revenue from contracts with customers [line items] |  |  |
Total revenue from contracts with customers | $ 2,845 | $ 3,355 | $ 2,976
Unrealized loss (gain) from risk management activities | (2) | 36 | (385)
At a point in time |  |  |
Disclosure of disaggregation of revenue from contracts with customers [line items] |  |  |
Total revenue from contracts with customers | 67 | 52 | 63
Over time |  |  |
Disclosure of disaggregation of revenue from contracts with customers [line items] |  |  |
Total revenue from contracts with customers | 823 | 634 | 713
Power and other |  |  |
Disclosure of disaggregation of revenue from contracts with customers [line items] |  |  |
Total revenue from contracts with customers | 784 | 646 | 725
Environmental and tax attributes |  |  |
Disclosure of disaggregation of revenue from contracts with customers [line items] |  |  |
Total revenue from contracts with customers | 106 | 40 | 51
Revenue from contracts with customers |  |  |
Disclosure of disaggregation of revenue from contracts with customers [line items] |  |  |
Total revenue from contracts with customers | 890 | 686 | 776
Revenue from derivatives and other trading activities |  |  |
Disclosure of disaggregation of revenue from contracts with customers [line items] |  |  |
Total revenue from contracts with customers | 708 | 327 | (541)
Revenue from merchant sales |  |  |
Disclosure of disaggregation of revenue from contracts with customers [line items] |  |  |
Total revenue from contracts with customers | 1,195 | 2,273 | 2,673
Other |  |  |
Disclosure of disaggregation of revenue from contracts with customers [line items] |  |  |
Total revenue from contracts with customers | 52 | 69 | 68
Hydro | Operating segments |  |  |
Disclosure of disaggregation of revenue from contracts with customers [line items] |  |  |
Total revenue from contracts with customers | 409 | 533 | 606
Hydro | Operating segments | At a point in time |  |  |
Disclosure of disaggregation of revenue from contracts with customers [line items] |  |  |
Total revenue from contracts with customers | 61 | 14 | 1
Hydro | Operating segments | Over time |  |  |
Disclosure of disaggregation of revenue from contracts with customers [line items] |  |  |
Total revenue from contracts with customers | 36 | 30 | 33
Hydro | Operating segments | Power and other |  |  |
Disclosure of disaggregation of revenue from contracts with customers [line items] |  |  |
Total revenue from contracts with customers | 36 | 30 | 33
Hydro | Operating segments | Environmental and tax attributes |  |  |
Disclosure of disaggregation of revenue from contracts with customers [line items] |  |  |
Total revenue from contracts with customers | 61 | 14 | 1
Hydro | Operating segments | Revenue from contracts with customers |  |  |
Disclosure of disaggregation of revenue from contracts with customers [line items] |  |  |
Total revenue from contracts with customers | 97 | 44 | 34
Hydro | Operating segments | Revenue from derivatives and other trading activities |  |  |
Disclosure of disaggregation of revenue from contracts with customers [line items] |  |  |
Total revenue from contracts with customers | 16 | 44 | 0
Hydro | Operating segments | Revenue from merchant sales |  |  |
Disclosure of disaggregation of revenue from contracts with customers [line items] |  |  |
Total revenue from contracts with customers | 287 | 434 | 564
Hydro | Operating segments | Other |  |  |
Disclosure of disaggregation of revenue from contracts with customers [line items] |  |  |
Total revenue from contracts with customers | 9 | 11 | 8
Wind and Solar |  |  |
Disclosure of disaggregation of revenue from contracts with customers [line items] |  |  |
Unrealized loss (gain) from risk management activities | 14 |  |
Wind and Solar | Operating segments |  |  |
Disclosure of disaggregation of revenue from contracts with customers [line items] |  |  |
Total revenue from contracts with customers | 336 | 336 | 289
Wind and Solar | Operating segments | At a point in time |  |  |
Disclosure of disaggregation of revenue from contracts with customers [line items] |  |  |
Total revenue from contracts with customers | 28 | 26 | 50
Wind and Solar | Operating segments | Over time |  |  |
Disclosure of disaggregation of revenue from contracts with customers [line items] |  |  |
Total revenue from contracts with customers | 291 | 204 | 220
Wind and Solar | Operating segments | Power and other |  |  |
Disclosure of disaggregation of revenue from contracts with customers [line items] |  |  |
Total revenue from contracts with customers | 242 | 204 | 220
Wind and Solar | Operating segments | Environmental and tax attributes |  |  |
Disclosure of disaggregation of revenue from contracts with customers [line items] |  |  |
Total revenue from contracts with customers | 77 | 26 | 50
Wind and Solar | Operating segments | Revenue from contracts with customers |  |  |
Disclosure of disaggregation of revenue from contracts with customers [line items] |  |  |
Total revenue from contracts with customers | 319 | 230 | 270
Wind and Solar | Operating segments | Revenue from derivatives and other trading activities |  |  |
Disclosure of disaggregation of revenue from contracts with customers [line items] |  |  |
Total revenue from contracts with customers | (69) | (16) | (121)
Wind and Solar | Operating segments | Revenue from merchant sales |  |  |
Disclosure of disaggregation of revenue from contracts with customers [line items] |  |  |
Total revenue from contracts with customers | 71 | 104 | 119
Wind and Solar | Operating segments | Other |  |  |
Disclosure of disaggregation of revenue from contracts with customers [line items] |  |  |
Total revenue from contracts with customers | 15 | 18 | 21
Gas | Operating segments |  |  |
Disclosure of disaggregation of revenue from contracts with customers [line items] |  |  |
Total revenue from contracts with customers | 1,350 | 1,514 | 1,209
Gas | Operating segments | At a point in time |  |  |
Disclosure of disaggregation of revenue from contracts with customers [line items] |  |  |
Total revenue from contracts with customers | 0 | 0 | 0
Gas | Operating segments | Over time |  |  |
Disclosure of disaggregation of revenue from contracts with customers [line items] |  |  |
Total revenue from contracts with customers | 496 | 400 | 462
Gas | Operating segments | Power and other |  |  |
Disclosure of disaggregation of revenue from contracts with customers [line items] |  |  |
Total revenue from contracts with customers | 494 | 400 | 462
Gas | Operating segments | Environmental and tax attributes |  |  |
Disclosure of disaggregation of revenue from contracts with customers [line items] |  |  |
Total revenue from contracts with customers | 2 | 0 | 0
Gas | Operating segments | Revenue from contracts with customers |  |  |
Disclosure of disaggregation of revenue from contracts with customers [line items] |  |  |
Total revenue from contracts with customers | 496 | 400 | 462
Gas | Operating segments | Revenue from derivatives and other trading activities |  |  |
Disclosure of disaggregation of revenue from contracts with customers [line items] |  |  |
Total revenue from contracts with customers | 282 | (172) | (821)
Gas | Operating segments | Revenue from merchant sales |  |  |
Disclosure of disaggregation of revenue from contracts with customers [line items] |  |  |
Total revenue from contracts with customers | 546 | 1,247 | 1,529
Gas | Operating segments | Other |  |  |
Disclosure of disaggregation of revenue from contracts with customers [line items] |  |  |
Total revenue from contracts with customers | 26 | 39 | 39
Energy Transition | Operating segments |  |  |
Disclosure of disaggregation of revenue from contracts with customers [line items] |  |  |
Total revenue from contracts with customers | 616 | 751 | 714
Energy Transition | Operating segments | At a point in time |  |  |
Disclosure of disaggregation of revenue from contracts with customers [line items] |  |  |
Total revenue from contracts with customers | 12 | 12 | 12
Energy Transition | Operating segments | Over time |  |  |
Disclosure of disaggregation of revenue from contracts with customers [line items] |  |  |
Total revenue from contracts with customers | 0 | 0 | (2)
Energy Transition | Operating segments | Power and other |  |  |
Disclosure of disaggregation of revenue from contracts with customers [line items] |  |  |
Total revenue from contracts with customers | 12 | 12 | 10
Energy Transition | Operating segments | Environmental and tax attributes |  |  |
Disclosure of disaggregation of revenue from contracts with customers [line items] |  |  |
Total revenue from contracts with customers | 0 | 0 | 0
Energy Transition | Operating segments | Revenue from contracts with customers |  |  |
Disclosure of disaggregation of revenue from contracts with customers [line items] |  |  |
Total revenue from contracts with customers | 12 | 12 | 10
Energy Transition | Operating segments | Revenue from derivatives and other trading activities |  |  |
Disclosure of disaggregation of revenue from contracts with customers [line items] |  |  |
Total revenue from contracts with customers | 311 | 251 | 243
Energy Transition | Operating segments | Revenue from merchant sales |  |  |
Disclosure of disaggregation of revenue from contracts with customers [line items] |  |  |
Total revenue from contracts with customers | 291 | 488 | 461
Energy Transition | Operating segments | Other |  |  |
Disclosure of disaggregation of revenue from contracts with customers [line items] |  |  |
Total revenue from contracts with customers | 2 | 0 | 0
Energy Marketing | Operating segments |  |  |
Disclosure of disaggregation of revenue from contracts with customers [line items] |  |  |
Total revenue from contracts with customers | 168 | 220 | 160
Energy Marketing | Operating segments | At a point in time |  |  |
Disclosure of disaggregation of revenue from contracts with customers [line items] |  |  |
Total revenue from contracts with customers | 0 | 0 | 0
Energy Marketing | Operating segments | Over time |  |  |
Disclosure of disaggregation of revenue from contracts with customers [line items] |  |  |
Total revenue from contracts with customers | 0 | 0 | 0
Energy Marketing | Operating segments | Power and other |  |  |
Disclosure of disaggregation of revenue from contracts with customers [line items] |  |  |
Total revenue from contracts with customers | 0 | 0 | 0
Energy Marketing | Operating segments | Environmental and tax attributes |  |  |
Disclosure of disaggregation of revenue from contracts with customers [line items] |  |  |
Total revenue from contracts with customers | 0 | 0 | 0
Energy Marketing | Operating segments | Revenue from contracts with customers |  |  |
Disclosure of disaggregation of revenue from contracts with customers [line items] |  |  |
Total revenue from contracts with customers | 0 | 0 | 0
Energy Marketing | Operating segments | Revenue from derivatives and other trading activities |  |  |
Disclosure of disaggregation of revenue from contracts with customers [line items] |  |  |
Total revenue from contracts with customers | 168 | 220 | 160
Energy Marketing | Operating segments | Revenue from merchant sales |  |  |
Disclosure of disaggregation of revenue from contracts with customers [line items] |  |  |
Total revenue from contracts with customers | 0 | 0 | 0
Energy Marketing | Operating segments | Other |  |  |
Disclosure of disaggregation of revenue from contracts with customers [line items] |  |  |
Total revenue from contracts with customers | 0 | 0 | 0
Corporate |  |  |
Disclosure of disaggregation of revenue from contracts with customers [line items] |  |  |
Total revenue from contracts with customers | (34) | 1 | (2)
Corporate | At a point in time |  |  |
Disclosure of disaggregation of revenue from contracts with customers [line items] |  |  |
Total revenue from contracts with customers | (34) | 0 | 0
Corporate | Over time |  |  |
Disclosure of disaggregation of revenue from contracts with customers [line items] |  |  |
Total revenue from contracts with customers | 0 | 0 | 0
Corporate | Power and other |  |  |
Disclosure of disaggregation of revenue from contracts with customers [line items] |  |  |
Total revenue from contracts with customers | 0 | 0 | 0
Corporate | Environmental and tax attributes |  |  |
Disclosure of disaggregation of revenue from contracts with customers [line items] |  |  |
Total revenue from contracts with customers | (34) | 0 | 0
Corporate | Revenue from contracts with customers |  |  |
Disclosure of disaggregation of revenue from contracts with customers [line items] |  |  |
Total revenue from contracts with customers | (34) | 0 | 0
Corporate | Revenue from derivatives and other trading activities |  |  |
Disclosure of disaggregation of revenue from contracts with customers [line items] |  |  |
Total revenue from contracts with customers | 0 | 0 | (2)
Corporate | Revenue from merchant sales |  |  |
Disclosure of disaggregation of revenue from contracts with customers [line items] |  |  |
Total revenue from contracts with customers | 0 | 0 | 0
Corporate | Other |  |  |
Disclosure of disaggregation of revenue from contracts with customers [line items] |  |  |
Total revenue from contracts with customers | $ 0 | $ 1 | $ 0

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