XML 43 R176.htm IDEA: XBRL DOCUMENT
v3.19.3.a.u2

Employee Future Benefits - Sensitivity Analysis (Details) $ in Thousands | Dec. 31, 2019 CAD ($)
--- | ---
1% decrease in the discount rate |
Disclosure of sensitivity analysis for actuarial assumptions [line items] |
Percentage of reasonably possible increase in actuarial assumption (as percent) | 1.00%
1% increase in the salary scale |
Disclosure of sensitivity analysis for actuarial assumptions [line items] |
Percentage of reasonably possible increase in actuarial assumption (as percent) | 1.00%
1% increase in the health-care cost trend rate |
Disclosure of sensitivity analysis for actuarial assumptions [line items] |
Percentage of reasonably possible increase in actuarial assumption (as percent) | 1.00%
10% improvement in mortality rates |
Disclosure of sensitivity analysis for actuarial assumptions [line items] |
Percentage of reasonably possible increase in actuarial assumption (as percent) | 10.00%
Registered Pension Plan | Canada | 1% decrease in the discount rate |
Disclosure of sensitivity analysis for actuarial assumptions [line items] |
Increase in defined benefit obligation | $ 84,000
Registered Pension Plan | Canada | 1% increase in the salary scale |
Disclosure of sensitivity analysis for actuarial assumptions [line items] |
Increase in defined benefit obligation | 14,000
Registered Pension Plan | Canada | 1% increase in the health-care cost trend rate |
Disclosure of sensitivity analysis for actuarial assumptions [line items] |
Increase in defined benefit obligation | 0
Registered Pension Plan | Canada | 10% improvement in mortality rates |
Disclosure of sensitivity analysis for actuarial assumptions [line items] |
Increase in defined benefit obligation | 22,000
Registered Pension Plan | UNITED STATES | 1% decrease in the discount rate |
Disclosure of sensitivity analysis for actuarial assumptions [line items] |
Increase in defined benefit obligation | 3,000
Registered Pension Plan | UNITED STATES | 1% increase in the salary scale |
Disclosure of sensitivity analysis for actuarial assumptions [line items] |
Increase in defined benefit obligation | 0
Registered Pension Plan | UNITED STATES | 1% increase in the health-care cost trend rate |
Disclosure of sensitivity analysis for actuarial assumptions [line items] |
Increase in defined benefit obligation | 0
Registered Pension Plan | UNITED STATES | 10% improvement in mortality rates |
Disclosure of sensitivity analysis for actuarial assumptions [line items] |
Increase in defined benefit obligation | 1,000
Supplemental Pension Plan | Canada | 1% decrease in the discount rate |
Disclosure of sensitivity analysis for actuarial assumptions [line items] |
Increase in defined benefit obligation | 15,000
Supplemental Pension Plan | Canada | 1% increase in the salary scale |
Disclosure of sensitivity analysis for actuarial assumptions [line items] |
Increase in defined benefit obligation | 0
Supplemental Pension Plan | Canada | 1% increase in the health-care cost trend rate |
Disclosure of sensitivity analysis for actuarial assumptions [line items] |
Increase in defined benefit obligation | 0
Supplemental Pension Plan | Canada | 10% improvement in mortality rates |
Disclosure of sensitivity analysis for actuarial assumptions [line items] |
Increase in defined benefit obligation | 3,000
Other | Canada | 1% decrease in the discount rate |
Disclosure of sensitivity analysis for actuarial assumptions [line items] |
Increase in defined benefit obligation | 2,000
Other | Canada | 1% increase in the salary scale |
Disclosure of sensitivity analysis for actuarial assumptions [line items] |
Increase in defined benefit obligation | 0
Other | Canada | 1% increase in the health-care cost trend rate |
Disclosure of sensitivity analysis for actuarial assumptions [line items] |
Increase in defined benefit obligation | 2,000
Other | Canada | 10% improvement in mortality rates |
Disclosure of sensitivity analysis for actuarial assumptions [line items] |
Increase in defined benefit obligation | 0
Other | UNITED STATES | 1% decrease in the discount rate |
Disclosure of sensitivity analysis for actuarial assumptions [line items] |
Increase in defined benefit obligation | 1,000
Other | UNITED STATES | 1% increase in the salary scale |
Disclosure of sensitivity analysis for actuarial assumptions [line items] |
Increase in defined benefit obligation | 0
Other | UNITED STATES | 1% increase in the health-care cost trend rate |
Disclosure of sensitivity analysis for actuarial assumptions [line items] |
Increase in defined benefit obligation | 0
Other | UNITED STATES | 10% improvement in mortality rates |
Disclosure of sensitivity analysis for actuarial assumptions [line items] |
Increase in defined benefit obligation | $ 0

X
- Definition Line items represent concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes of the table. + References No definition available. + Details
Name: | ifrs-full_DisclosureOfSensitivityAnalysisForActuarialAssumptionsLineItems
Namespace Prefix: | ifrs-full_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition The increase (decrease) in a defined benefit obligation that would have been caused by an increase in a significant actuarial assumption that was reasonably possible at the end of the reporting period. [Refer: Actuarial assumptions [member]] + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Name IAS -Number 19 -IssueDate 2018-01-01 -Paragraph 145 -Subparagraph a -URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=19&date=2018-03-01&anchor=para_145_a&doctype=Standard -URIDate 2018-03-16 + Details
Name: | ifrs-full_IncreaseDecreaseInDefinedBenefitObligationDueToReasonablyPossibleIncreaseInActuarialAssumption
Namespace Prefix: | ifrs-full_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition The reasonably possible percentage of the increase in the actuarial assumption used to determine the present value of defined benefit obligation. [Refer: Actuarial assumptions [member]] + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Name IAS -Number 19 -IssueDate 2018-01-01 -Paragraph 145 -Subparagraph a -URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=19&date=2018-03-01&anchor=para_145_a&doctype=Standard -URIDate 2018-03-16 + Details
Name: | ifrs-full_PercentageOfReasonablyPossibleIncreaseInActuarialAssumption
Namespace Prefix: | ifrs-full_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | instant

X
- Details
Name: | ifrs-full_ActuarialAssumptionsAxis=ifrs-full_ActuarialAssumptionOfDiscountRatesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | ifrs-full_ActuarialAssumptionsAxis=ifrs-full_ActuarialAssumptionOfExpectedRatesOfSalaryIncreasesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | ifrs-full_ActuarialAssumptionsAxis=ifrs-full_ActuarialAssumptionOfMedicalCostTrendRatesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | ifrs-full_ActuarialAssumptionsAxis=ifrs-full_ActuarialAssumptionOfMortalityRatesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | ifrs-full_CharacteristicsOfDefinedBenefitPlansAxis=tac_RegisteredPensionPlanMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_StatementGeographicalAxis=country_CA
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_StatementGeographicalAxis=country_US
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | ifrs-full_CharacteristicsOfDefinedBenefitPlansAxis=tac_SupplementalPensionPlanMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | ifrs-full_CharacteristicsOfDefinedBenefitPlansAxis=tac_OtherPostEmploymentBenefitPlansMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |