XML 155 R127.htm IDEA: XBRL DOCUMENT
v3.8.0.1

Risk Management Activities - Commodity Risk Management (Details) - Commodity risk management t in Thousands, gal in Thousands, kJ in Billions | Dec. 31, 2017 MWh kJ t gal | Dec. 31, 2016 MWh kJ t gal
--- | --- | ---
Electricity [Member] | Cash flow hedges |  |
Disclosure of detailed information about hedges [line items] |  |
Notional amount sold | 1,997,000 | 4,916,000
Notional amount purchased | 44,000 | 0
Electricity [Member] | Non-Hedges [Member] |  |
Disclosure of detailed information about hedges [line items] |  |
Notional amount sold | 14,688,000 | 19,362,000
Notional amount purchased | 7,348,000 | 19,060,000
Natural gas | Non-Hedges [Member] |  |
Disclosure of detailed information about hedges [line items] |  |
Notional amount sold | kJ | 74,194 | 146,113
Notional amount purchased | kJ | 103,805 | 173,187
Transmission | Non-Hedges [Member] |  |
Disclosure of detailed information about hedges [line items] |  |
Notional amount sold | 1,000 | 0
Notional amount purchased | 3,455,000 | 3,429,000
Emissions | Non-Hedges [Member] |  |
Disclosure of detailed information about hedges [line items] |  |
Derivative, Nonmonetary Notional Amount Sold, Emissions | t | 516 | 1,370
Derivative, Nonmonetary Notional Amount Purchased, Emissions | t | 717 | 1,370
Heating Oil | Non-Hedges [Member] |  |
Disclosure of detailed information about hedges [line items] |  |
Derivative, Nonmonetary Notional Amount Sold In Gallons | gal | 0 | 0
Derivative, Nonmonetary Notional Amount Purchased In Gallons | gal | 0 | 294

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_DisclosureOfHedgeAccountingLineItems
Namespace Prefix: | ifrs-full_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Derivative, Nonmonetary Notional Amount Purchased + References No definition available. + Details
Name: | tac_DerivativeNonmonetaryNotionalAmountPurchased
Namespace Prefix: | tac_
Data Type: | num:energyItemType
Balance Type: | na
Period Type: | instant

X
- Definition Derivative, Nonmonetary Notional Amount Purchased, Emissions + References No definition available. + Details
Name: | tac_DerivativeNonmonetaryNotionalAmountPurchasedEmissions
Namespace Prefix: | tac_
Data Type: | num:massItemType
Balance Type: | na
Period Type: | instant

X
- Definition Derivative, Nonmonetary Notional Amount Purchased In Gallons + References No definition available. + Details
Name: | tac_DerivativeNonmonetaryNotionalAmountPurchasedInGallons
Namespace Prefix: | tac_
Data Type: | num:volumeItemType
Balance Type: | na
Period Type: | instant

X
- Definition Derivative, Nonmonetary Notional Amount Sold + References No definition available. + Details
Name: | tac_DerivativeNonmonetaryNotionalAmountSold
Namespace Prefix: | tac_
Data Type: | num:energyItemType
Balance Type: | na
Period Type: | instant

X
- Definition Derivative, Nonmonetary Notional Amount Sold, Emissions + References No definition available. + Details
Name: | tac_DerivativeNonmonetaryNotionalAmountSoldEmissions
Namespace Prefix: | tac_
Data Type: | num:massItemType
Balance Type: | na
Period Type: | instant

X
- Definition Derivative, Nonmonetary Notional Amount Sold In Gallons + References No definition available. + Details
Name: | tac_DerivativeNonmonetaryNotionalAmountSoldInGallons
Namespace Prefix: | tac_
Data Type: | num:volumeItemType
Balance Type: | na
Period Type: | instant

X
- Details
Name: | ifrs-full_HedgingInstrumentsAxis=tac_ElectricityMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | ifrs-full_TypesOfRisksAxis=ifrs-full_CommodityPriceRiskMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | ifrs-full_TypesOfHedgesAxis=ifrs-full_CashFlowHedgesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | ifrs-full_TypesOfHedgesAxis=tac_NonHedgesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | ifrs-full_HedgingInstrumentsAxis=tac_NaturalGasMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | ifrs-full_HedgingInstrumentsAxis=tac_TransmissionMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | ifrs-full_HedgingInstrumentsAxis=tac_EmissionsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | ifrs-full_HedgingInstrumentsAxis=tac_HeatingOil1Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |