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v3.19.3.a.u2

Credit Facilities, Long-Term Debt, and Finance Lease Obligations - Debentures (Details) - CAD ($) $ in Millions |  |  | 12 Months Ended
--- | --- | --- | ---
Aug. 02, 2018 | Jul. 20, 2018 | Dec. 31, 2019 | Dec. 31, 2018 | Dec. 31, 2017
Disclosure of detailed information about borrowings [line items] |  |  |  |  |
Notional amount |  |  | $ 3,104 | $ 3,234 |
Borrowings |  |  | 3,212 | 3,267 |
Alberta off-coal agreement, annual cash payments, gross |  | $ 40 | 40 | 40 | $ 40
Alberta off-coal agreement, annual cash payments, net |  | $ 37 |  |  |
Debentures |  |  |  |  |
Disclosure of detailed information about borrowings [line items] |  |  |  |  |
Notional amount |  |  | 651 | 651 |
Redemption of unsecured debt | $ 425 |  |  |  |
Redemption of prepayment premium recognized in net interest expense | 19 |  |  |  |
Accrued and unpaid interest | $ 6 |  |  |  |
Interest rate | 6.40% | 6.40% |  |  |
Borrowings | $ 400 |  | $ 647 | $ 647 |
Debentures | Minimum |  |  |  |  |
Disclosure of detailed information about borrowings [line items] |  |  |  |  |
Interest rate |  |  |  | 5.00% |
Debentures | Maximum |  |  |  |  |
Disclosure of detailed information about borrowings [line items] |  |  |  |  |
Interest rate |  |  |  | 7.30% |

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