XML 155 R127.htm IDEA: XBRL DOCUMENT v3.20.4

Risk Management Activities - Non-Hedges (Details) € in Millions, $ in Millions, $ in Millions, $ in Millions	Dec. 31, 2020 CAD ($)	Dec. 31, 2020 USD ($)	Dec. 31, 2020 AUD ($)	Dec. 31, 2020 EUR (€)	Dec. 31, 2019 CAD ($)	Dec. 31, 2019 USD ($)	Dec. 31, 2019 AUD ($)
Disclosure of detailed information about hedges [line items]
Hedging instrument, assets	$ 2				$ 7
Foreign exchange forward contracts – foreign-denominated receipts/expenditures | Discontinued Hedge Positions | Currency risk | Maturity, 2021-2024, Contract One
Disclosure of detailed information about hedges [line items]
Hedging instrument, liabilities	(14)
Foreign exchange forward contracts – foreign-denominated receipts/expenditures | Discontinued Hedge Positions | Currency risk | Maturity, 2021-2024, Contract Two
Disclosure of detailed information about hedges [line items]
Hedging instrument, assets	9
Foreign exchange forward contracts – foreign-denominated receipts/expenditures | Discontinued Hedge Positions | Currency risk | Maturity, 2021, Contract One
Disclosure of detailed information about hedges [line items]
Hedging instrument, assets	0
Foreign exchange forward contracts – foreign-denominated receipts/expenditures | Discontinued Hedge Positions | Currency risk | Maturity, 2021, Contract Two
Disclosure of detailed information about hedges [line items]
Hedging instrument, assets	0
Foreign exchange forward contracts – foreign-denominated receipts/expenditures | Discontinued Hedge Positions | Currency risk | Maturity, 2020-2023, Contract One
Disclosure of detailed information about hedges [line items]
Hedging instrument, assets					0
Foreign exchange forward contracts – foreign-denominated receipts/expenditures | Discontinued Hedge Positions | Currency risk | Maturity, 2020-2023, Contract Two
Disclosure of detailed information about hedges [line items]
Hedging instrument, liabilities					(4)
Foreign exchange forward contracts – foreign-denominated debt | Discontinued Hedge Positions | Currency risk | Maturity, 2022
Disclosure of detailed information about hedges [line items]
Hedging instrument, assets	2				6
Australia, Dollars | Foreign exchange forward contracts – foreign-denominated receipts/expenditures | Discontinued Hedge Positions | Currency risk | Maturity, 2021-2024, Contract One
Disclosure of detailed information about hedges [line items]
Notional amount sold			$ 197
Australia, Dollars | Foreign exchange forward contracts – foreign-denominated receipts/expenditures | Discontinued Hedge Positions | Currency risk | Maturity, 2021, Contract One
Disclosure of detailed information about hedges [line items]
Notional amount sold			$ 4
Australia, Dollars | Foreign exchange forward contracts – foreign-denominated receipts/expenditures | Discontinued Hedge Positions | Currency risk | Maturity, 2020-2023, Contract One
Disclosure of detailed information about hedges [line items]
Notional amount sold							$ 286
Canada, Dollars | Foreign exchange forward contracts – foreign-denominated receipts/expenditures | Discontinued Hedge Positions | Currency risk | Maturity, 2021-2024, Contract One
Disclosure of detailed information about hedges [line items]
Derivative, notional amount purchased	181
Canada, Dollars | Foreign exchange forward contracts – foreign-denominated receipts/expenditures | Discontinued Hedge Positions | Currency risk | Maturity, 2021-2024, Contract Two
Disclosure of detailed information about hedges [line items]
Derivative, notional amount purchased	72
Canada, Dollars | Foreign exchange forward contracts – foreign-denominated receipts/expenditures | Discontinued Hedge Positions | Currency risk | Maturity, 2021, Contract Two
Disclosure of detailed information about hedges [line items]
Notional amount sold	1
Canada, Dollars | Foreign exchange forward contracts – foreign-denominated receipts/expenditures | Discontinued Hedge Positions | Currency risk | Maturity, 2020-2023, Contract One
Disclosure of detailed information about hedges [line items]
Derivative, notional amount purchased					266
Canada, Dollars | Foreign exchange forward contracts – foreign-denominated receipts/expenditures | Discontinued Hedge Positions | Currency risk | Maturity, 2020-2023, Contract Two
Disclosure of detailed information about hedges [line items]
Derivative, notional amount purchased					139
Canada, Dollars | Foreign exchange forward contracts – foreign-denominated debt | Discontinued Hedge Positions | Currency risk | Maturity, 2022
Disclosure of detailed information about hedges [line items]
Notional amount sold	$ 191				$ 191
Derivative, notional amount purchased		$ 150				$ 150
U.S. Dollars | Foreign exchange forward contracts – foreign-denominated receipts/expenditures | Discontinued Hedge Positions | Currency risk | Maturity, 2021-2024, Contract Two
Disclosure of detailed information about hedges [line items]
Notional amount sold		47
U.S. Dollars | Foreign exchange forward contracts – foreign-denominated receipts/expenditures | Discontinued Hedge Positions | Currency risk | Maturity, 2021, Contract One
Disclosure of detailed information about hedges [line items]
Derivative, notional amount purchased		$ 3
U.S. Dollars | Foreign exchange forward contracts – foreign-denominated receipts/expenditures | Discontinued Hedge Positions | Currency risk | Maturity, 2020-2023, Contract Two
Disclosure of detailed information about hedges [line items]
Notional amount sold						$ 108
Euro Member Countries, Euro | Foreign exchange forward contracts – foreign-denominated receipts/expenditures | Discontinued Hedge Positions | Currency risk | Maturity, 2021, Contract Two
Disclosure of detailed information about hedges [line items]
Derivative, notional amount purchased | €				€ 1

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

The amount of a hedging instrument, recognised as an asset. [Refer: Hedging instruments [member]]

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IFRS
-Number 7
-IssueDate 2019-01-01
-Paragraph 24A
-Subparagraph a
-URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IFRS&num=7&code=ifrs-tx-2019-en-r&anchor=para_24A_a&doctype=Standard
-URIDate 2019-03-27

+ Details

Name:	ifrs-full_HedgingInstrumentAssets
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

X

- Definition

The amount of a hedging instrument, recognised as a liability. [Refer: Hedging instruments [member]]

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IFRS
-Number 7
-IssueDate 2019-01-01
-Paragraph 24A
-Subparagraph a
-URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IFRS&num=7&code=ifrs-tx-2019-en-r&anchor=para_24A_a&doctype=Standard
-URIDate 2019-03-27

+ Details

Name:	ifrs-full_HedgingInstrumentLiabilities
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

X

- Definition

Derivative, Notional Amount Purchased

+ References

No definition available.

+ Details

Name:	tac_DerivativeNotionalAmountPurchased
Namespace Prefix:	tac_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

X

- Definition

Derivative, Notional Amount Sold

+ References

No definition available.

+ Details

Name:	tac_DerivativeNotionalAmountSold
Namespace Prefix:	tac_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

X

- Details

Name:	ifrs-full_HedgingInstrumentsAxis=tac_ForeignExchangeForwardContractsForeignDenominatedReceiptsExpendituresMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	ifrs-full_TypesOfHedgesAxis=tac_DiscontinuedHedgePositionsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	ifrs-full_TypesOfRisksAxis=ifrs-full_CurrencyRiskMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	ifrs-full_MaturityAxis=tac_Maturity20212024ContractOneMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	ifrs-full_MaturityAxis=tac_Maturity20212024ContractTwoMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	ifrs-full_MaturityAxis=tac_Maturity2021ContractOneMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	ifrs-full_MaturityAxis=tac_Maturity2021ContractTwoMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	ifrs-full_MaturityAxis=tac_Maturity20202023ContractOneMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	ifrs-full_MaturityAxis=tac_Maturity20202023ContractTwoMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	ifrs-full_HedgingInstrumentsAxis=tac_ForeignExchangeForwardContractsForeignDenominatedDebtMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	ifrs-full_MaturityAxis=tac_Maturity2022Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	srt_CurrencyAxis=currency_AUD
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	srt_CurrencyAxis=currency_CAD
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	srt_CurrencyAxis=currency_USD
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	srt_CurrencyAxis=currency_EUR
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: