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Financial Instruments Sensitivity ranges for the base fair values (Details) number in Millions, $ in Millions | 12 Months Ended
--- | ---
Dec. 31, 2018 CAD ($) | Dec. 31, 2017 CAD ($)
Disclosure of sensitivity analysis for actuarial assumptions [line items] |  |
Base fair value | $ 3,234 | $ 3,664
Long-Term Power Sale - U.S. | Long-term contracts |  |
Disclosure of sensitivity analysis for actuarial assumptions [line items] |  |
Base fair value | 801 | 853
Long-Term Power Sale - Alberta | Long-term contracts |  |
Disclosure of sensitivity analysis for actuarial assumptions [line items] |  |
Base fair value | 4 | (1)
Unit Contingent Power Purchases |  |
Disclosure of sensitivity analysis for actuarial assumptions [line items] |  |
Base fair value | 18 | 44
Structured Products - Eastern U.S. |  |
Disclosure of sensitivity analysis for actuarial assumptions [line items] |  |
Base fair value | 6 | 17
Long-Term Wind Energy Sale - Eastern U.S. |  |
Disclosure of sensitivity analysis for actuarial assumptions [line items] |  |
Base fair value | (39) | 0
Others |  |
Disclosure of sensitivity analysis for actuarial assumptions [line items] |  |
Base fair value | $ 4 | $ 5
Maximum | Long-Term Power Sale - U.S. | Long-term contracts |  |
Disclosure of sensitivity analysis for actuarial assumptions [line items] |  |
Sensitivity ranges for the base fair value, reasonably possible change in risk assumption, financial instruments | (116) | (130)
Maximum | Long-Term Power Sale - Alberta | Long-term contracts |  |
Disclosure of sensitivity analysis for actuarial assumptions [line items] |  |
Sensitivity ranges for the base fair value, reasonably possible change in risk assumption, financial instruments | (1) | (2)
Maximum | Unit Contingent Power Purchases |  |
Disclosure of sensitivity analysis for actuarial assumptions [line items] |  |
Sensitivity ranges for the base fair value, reasonably possible change in risk assumption, financial instruments | (4) | (7)
Maximum | Structured Products - Eastern U.S. |  |
Disclosure of sensitivity analysis for actuarial assumptions [line items] |  |
Sensitivity ranges for the base fair value, reasonably possible change in risk assumption, financial instruments | (5) | (8)
Maximum | Long-Term Wind Energy Sale - Eastern U.S. |  |
Disclosure of sensitivity analysis for actuarial assumptions [line items] |  |
Sensitivity ranges for the base fair value, reasonably possible change in risk assumption, financial instruments | (21) | 0
Maximum | Others |  |
Disclosure of sensitivity analysis for actuarial assumptions [line items] |  |
Sensitivity ranges for the base fair value, reasonably possible change in risk assumption, financial instruments | (3) | (9)
Minimum | Long-Term Power Sale - U.S. | Long-term contracts |  |
Disclosure of sensitivity analysis for actuarial assumptions [line items] |  |
Sensitivity ranges for the base fair value, reasonably possible change in risk assumption, financial instruments | 116 | 130
Minimum | Long-Term Power Sale - Alberta | Long-term contracts |  |
Disclosure of sensitivity analysis for actuarial assumptions [line items] |  |
Sensitivity ranges for the base fair value, reasonably possible change in risk assumption, financial instruments | 1 | 2
Minimum | Unit Contingent Power Purchases |  |
Disclosure of sensitivity analysis for actuarial assumptions [line items] |  |
Sensitivity ranges for the base fair value, reasonably possible change in risk assumption, financial instruments | 4 | 9
Minimum | Structured Products - Eastern U.S. |  |
Disclosure of sensitivity analysis for actuarial assumptions [line items] |  |
Sensitivity ranges for the base fair value, reasonably possible change in risk assumption, financial instruments | 5 | 7
Minimum | Long-Term Wind Energy Sale - Eastern U.S. |  |
Disclosure of sensitivity analysis for actuarial assumptions [line items] |  |
Sensitivity ranges for the base fair value, reasonably possible change in risk assumption, financial instruments | 21 | 0
Minimum | Others |  |
Disclosure of sensitivity analysis for actuarial assumptions [line items] |  |
Sensitivity ranges for the base fair value, reasonably possible change in risk assumption, financial instruments | 3 | 9

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- Definition The nominal or face amount of a financial instrument, used to calculate payments made on that instrument. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Name IAS -Number 1 -IssueDate 2017-01-01 -Paragraph 112 -Subparagraph c -URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=1&date=2017-03-01&anchor=para_112_c&doctype=Standard -URIDate 2017-03-09 + Details
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- Definition Sensitivity Ranges For The Base Fair Value, Reasonably Possible Increase (Decrease) In Risk Assumption, Financial Instruments + References No definition available. + Details
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