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v3.19.3.a.u2

Credit Facilities, Long-Term Debt, and Finance Lease Obligations - Senior Notes (Details) $ in Millions, $ in Millions |  | 12 Months Ended |  |  |
--- | --- | --- | --- | --- | ---
Mar. 15, 2018 USD ($) | Mar. 15, 2018 CAD ($) | Dec. 31, 2018 USD ($) | Dec. 31, 2018 CAD ($) | Dec. 31, 2019 CAD ($) | Dec. 31, 2018 CAD ($) | Dec. 31, 2017 USD ($) | Dec. 31, 2017 CAD ($)
Disclosure of detailed information about borrowings [line items] |  |  |  |  |  |  |  |
Notional amount |  |  |  |  | $ 3,104 | $ 3,234 |  |
Borrowings |  |  |  |  | $ 3,212 | $ 3,267 |  |
Senior notes | Minimum |  |  |  |  |  |  |  |
Disclosure of detailed information about borrowings [line items] |  |  |  |  |  |  |  |
Interest rate |  |  | 4.50% |  |  | 4.50% |  |
Senior notes | Maximum |  |  |  |  |  |  |  |
Disclosure of detailed information about borrowings [line items] |  |  |  |  |  |  |  |
Interest rate |  |  | 6.50% |  |  | 6.50% |  |
6.65% Senior notes, due May 2018 |  |  |  |  |  |  |  |
Disclosure of detailed information about borrowings [line items] |  |  |  |  |  |  |  |
Interest rate | 6.65% |  | 6.65% |  |  | 6.65% |  |
Borrowings | $ 500 |  | $ 500 |  |  |  |  |
Redemption of noncurrent borrowings | $ 516 | $ 617 | $ 516 | $ 617 |  |  |  |
Redemption of prepayment premium recognized in net interest expense |  | $ 5 |  | 5 |  |  |  |
Accrued and unpaid interest |  |  |  | $ 14 |  |  |  |
4.75% Senior Notes due 2015 | Senior notes |  |  |  |  |  |  |  |
Disclosure of detailed information about borrowings [line items] |  |  |  |  |  |  |  |
Interest rate |  |  |  |  |  |  | 1.90% | 1.90%
Notional amount |  |  |  |  |  |  | $ 400 |
Borrowings |  |  |  |  |  |  |  | $ 434
Non-Recourse Bonds |  |  |  |  |  |  |  |
Disclosure of detailed information about borrowings [line items] |  |  |  |  |  |  |  |
Interest rate |  |  | 4.509% |  |  | 4.509% |  |

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