XML 189 R161.htm IDEA: XBRL DOCUMENT
v3.8.0.1

Accumulated Other Comprehensive Income (Details) - CAD | 3 Months Ended | 12 Months Ended
--- | --- | ---
Mar. 31, 2017 | Dec. 31, 2017 | Dec. 31, 2016 | Dec. 31, 2015
Components and changes in accumulated other comprehensive Income (loss) |  |  |  |  |  |  |  |
Accumulated other comprehensive income, beginning of the period |  | CAD 399,000,000 | CAD 399,000,000 |  |  |  |  |
Currency translation adjustment |  |  |  |  |  |  |  |
Losses on translating net assets of foreign operations, net of reclassifications to net earnings, net of tax |  |  | 25,000,000 |  | CAD 53,000,000 |  |  |
Gains (losses) on financial instruments designated as hedges of foreign operations, net of tax | [1] |  | 50,000,000 |  | 18,000,000 |  | CAD (172,000,000) |
Cash flow hedges |  |  |  |  |  |  |  |
Net gains on derivatives designated as cash flow hedges, net of tax |  | 3,000,000 | 214,000,000 | [2] | 179,000,000 | [2] | 375,000,000 | [2]
Other |  |  |  |  |  |  |  |
Intercompany available-for-sale investments |  |  | 0 |  | 0 |  |  |
Accumulated other comprehensive income, end of the period |  |  | 489,000,000 |  | 399,000,000 |  |  |
Income tax relating to exchange differences on translation of other comprehensive income |  |  | 0 |  | 11,000,000 |  | 0 |
Income tax relating to hedges of net investments in foreign operations of other comprehensive income |  |  | 2,000,000 |  | 5,000,000 |  | 7,000,000 |
Net impact related to cash flow hedges |  |  | (108,000,000) |  | 51,000,000 |  | 89,000,000 |
Income tax relating to net actuarial gains (losses) |  |  | (4,000,000) |  | 4,000,000 |  | 0 |
Reserve of exchange differences on translation [member] |  |  |  |  |  |  |  |
Components and changes in accumulated other comprehensive Income (loss) |  |  |  |  |  |  |  |
Accumulated other comprehensive income, beginning of the period |  | (1,000,000) | (1,000,000) |  | 52,000,000 |  |  |
Currency translation adjustment |  |  |  |  |  |  |  |
Losses on translating net assets of foreign operations, net of reclassifications to net earnings, net of tax |  |  | (89,000,000) |  | (71,000,000) |  |  |
Gains (losses) on financial instruments designated as hedges of foreign operations, net of tax |  |  | 64,000,000 |  | 18,000,000 |  |  |
Other |  |  |  |  |  |  |  |
Accumulated other comprehensive income, end of the period |  |  | (26,000,000) |  | (1,000,000) |  | 52,000,000 |
Income tax relating to exchange differences on translation of other comprehensive income |  |  | 11,000,000 |  | 11,000,000 |  |  |
Income tax relating to hedges of net investments in foreign operations of other comprehensive income |  |  | 4,000,000 |  | 5,000,000 |  |  |
Reserve of cash flow hedges [member] |  |  |  |  |  |  |  |
Components and changes in accumulated other comprehensive Income (loss) |  |  |  |  |  |  |  |
Accumulated other comprehensive income, beginning of the period |  | 456,000,000 | 456,000,000 |  | 350,000,000 |  |  |
Cash flow hedges |  |  |  |  |  |  |  |
Net gains on derivatives designated as cash flow hedges, net of tax |  |  | 106,000,000 |  | 106,000,000 |  |  |
Other |  |  |  |  |  |  |  |
Accumulated other comprehensive income, end of the period |  |  | 562,000,000 |  | 456,000,000 |  | 350,000,000 |
Net impact related to cash flow hedges |  |  | (108,000,000) |  | 51,000,000 |  |  |
Reserve of remeasurements of defined benefit plans [member] |  |  |  |  |  |  |  |
Components and changes in accumulated other comprehensive Income (loss) |  |  |  |  |  |  |  |
Accumulated other comprehensive income, beginning of the period |  | (38,000,000) | (38,000,000) |  | (46,000,000) |  |  |
Employee future benefits |  |  |  |  |  |  |  |
Net actuarial gains (losses) on defined benefit plans, net of tax |  |  | (6,000,000) |  | 8,000,000 |  |  |
Other |  |  |  |  |  |  |  |
Accumulated other comprehensive income, end of the period |  |  | (44,000,000) |  | (38,000,000) |  | (46,000,000) |
Income tax relating to net actuarial gains (losses) |  |  | (4,000,000) |  | 4,000,000 |  |  |
Other reserves [member] |  |  |  |  |  |  |  |
Components and changes in accumulated other comprehensive Income (loss) |  |  |  |  |  |  |  |
Accumulated other comprehensive income, beginning of the period |  | CAD (18,000,000) | (18,000,000) |  | (3,000,000) |  |  |
Other |  |  |  |  |  |  |  |
Change in ownership of TransAlta Renewables |  |  | 4,000,000 |  | 0 |  |  |
Intercompany available-for-sale investments |  |  | 11,000,000 |  | (15,000,000) |  |  |
Accumulated other comprehensive income, end of the period |  |  | CAD (3,000,000) |  | CAD (18,000,000) |  | CAD (3,000,000) |
[1] | (5) Net of income tax expense of 2 for the year ended Dec. 31, 2017 (2016 - 5 expense, 2015 - 7 expense)
[2] | (7) Net of income tax recovery of 77 for the year ended Dec. 31, 2017 (2016 - 92 expense, 2015 - 138 expense).

X
- Definition The amount of accumulated items of income and expense (including reclassification adjustments) that are not recognised in profit or loss as required or permitted by other IFRSs. [Refer: IFRSs [member]; Other comprehensive income] + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Name IAS -Number 1 -IssueDate 2017-01-01 -Paragraph 55 -URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=1&date=2017-03-01&anchor=para_55&doctype=Standard -URIDate 2017-03-09 + Details
Name: | ifrs-full_AccumulatedOtherComprehensiveIncome
Namespace Prefix: | ifrs-full_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition The decrease (increase) in a net defined benefit liability (asset) resulting from actuarial gains (losses) arising from changes in financial assumptions that result in remeasurements of the net defined benefit liability (asset). Financial assumptions deal with items such as: (a) the discount rate; (b) benefit levels, excluding any cost of the benefits to be met by employees, and future salary; (c) in the case of medical benefits, future medical costs, including claim handling costs (ie the costs that will be incurred in processing and resolving claims, including legal and adjuster's fees); and (d) taxes payable by the plan on contributions relating to service before the reporting date or on benefits resulting from that service. [Refer: Net defined benefit liability (asset)] + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Name IAS -Number 19 -IssueDate 2017-01-01 -Paragraph 141 -Subparagraph c -Clause iii -URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=19&date=2017-03-01&anchor=para_141_c_iii&doctype=Standard -URIDate 2017-03-09 + Details
Name: | ifrs-full_ActuarialGainsLossesArisingFromChangesInFinancialAssumptionsNetDefinedBenefitLiabilityAsset
Namespace Prefix: | ifrs-full_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- References No definition available. + Details
Name: | ifrs-full_CashFlowHedgesAbstract
Namespace Prefix: | ifrs-full_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- References No definition available. + Details
Name: | ifrs-full_ExchangeDifferencesOnTranslationAbstract
Namespace Prefix: | ifrs-full_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition The gains (losses) recognised in other comprehensive income on cash flow hedges, net of tax. [Refer: Cash flow hedges [member]] + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Note Expiry date 2018-01-01 -Name IFRS -Number 7 -IssueDate 2017-01-01 -Paragraph 23 -Subparagraph c -URI http://eifrs.ifrs.org/eifrs/XBRL?type=IFRS&num=7&date=2017-03-02&anchor=para_23_c&doctype=Standard&book=B -URIDate 2017-03-09 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Name IAS -Number 1 -IssueDate 2017-01-01 -Paragraph 91 -Subparagraph a -URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=1&date=2017-03-01&anchor=para_91_a&doctype=Standard -URIDate 2017-03-09 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Note Effective 2018-01-01 -Name IFRS -Number 7 -IssueDate 2017-01-01 -Paragraph 24C -Subparagraph b -Clause i -URI http://eifrs.ifrs.org/eifrs/XBRL?type=IFRS&num=7&date=2017-03-01&anchor=para_24C_b_i&doctype=Standard -URIDate 2017-03-09 Reference 4: http://www.xbrl.org/2003/role/disclosureRef -Note Effective 2018-01-01 -Name IFRS -Number 7 -IssueDate 2017-01-01 -Paragraph 24E -Subparagraph a -URI http://eifrs.ifrs.org/eifrs/XBRL?type=IFRS&num=7&date=2017-03-01&anchor=para_24E_a&doctype=Standard -URIDate 2017-03-09 + Details
Name: | ifrs-full_GainsLossesOnCashFlowHedgesNetOfTax
Namespace Prefix: | ifrs-full_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition The gains (losses) recognised in other comprehensive income on exchange differences on the translation of financial statements of foreign operations, net of tax. [Refer: Other comprehensive income] + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Name IAS -Number 1 -IssueDate 2017-01-01 -Paragraph 91 -Subparagraph a -URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=1&date=2017-03-01&anchor=para_91_a&doctype=Standard -URIDate 2017-03-09 + Details
Name: | ifrs-full_GainsLossesOnExchangeDifferencesOnTranslationNetOfTax
Namespace Prefix: | ifrs-full_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition The gains (losses) recognised in other comprehensive income on hedges of net investments in foreign operations, net of tax. [Refer: Other comprehensive income] + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Name IAS -Number 39 -IssueDate 2017-01-01 -Paragraph 102 -Subparagraph a -URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=39&date=2017-03-01&anchor=para_102_a&doctype=Standard -URIDate 2017-03-09 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Name IAS -Number 1 -IssueDate 2017-01-01 -Paragraph 91 -Subparagraph a -URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=1&date=2017-03-01&anchor=para_91_a&doctype=Standard -URIDate 2017-03-09 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Note Effective 2018-01-01 -Name IFRS -Number 7 -IssueDate 2017-01-01 -Paragraph 24C -Subparagraph b -Clause i -URI http://eifrs.ifrs.org/eifrs/XBRL?type=IFRS&num=7&date=2017-03-01&anchor=para_24C_b_i&doctype=Standard -URIDate 2017-03-09 Reference 4: http://www.xbrl.org/2003/role/disclosureRef -Note Effective 2018-01-01 -Name IFRS -Number 7 -IssueDate 2017-01-01 -Paragraph 24E -Subparagraph a -URI http://eifrs.ifrs.org/eifrs/XBRL?type=IFRS&num=7&date=2017-03-01&anchor=para_24E_a&doctype=Standard -URIDate 2017-03-09 Reference 5: http://www.xbrl.org/2003/role/disclosureRef -Note Effective 2018-01-01 -Name IFRS -Number 9 -IssueDate 2017-01-01 -Paragraph 6.5.13 -Subparagraph a -URI http://eifrs.ifrs.org/eifrs/XBRL?type=IFRS&num=9&date=2017-03-01&anchor=para_6.5.13_a&doctype=Standard -URIDate 2017-03-09 + Details
Name: | ifrs-full_GainsLossesOnHedgesOfNetInvestmentsInForeignOperationsNetOfTax
Namespace Prefix: | ifrs-full_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition The amount of income tax relating to amounts recognised in other comprehensive income in relation to cash flow hedges. [Refer: Cash flow hedges [member]; Other comprehensive income] + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Name IAS -Number 12 -IssueDate 2017-01-01 -Paragraph 81 -Subparagraph ab -URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=12&date=2017-03-01&anchor=para_81_ab&doctype=Standard -URIDate 2017-03-09 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Name IAS -Number 1 -IssueDate 2017-01-01 -Paragraph 90 -URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=1&date=2017-03-01&anchor=para_90&doctype=Standard -URIDate 2017-03-09 + Details
Name: | ifrs-full_IncomeTaxRelatingToCashFlowHedgesOfOtherComprehensiveIncome
Namespace Prefix: | ifrs-full_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition The amount of income tax relating to amounts recognised in other comprehensive income in relation to exchange differences on the translation of financial statements of foreign operations. [Refer: Other comprehensive income; Reserve of exchange differences on translation] + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Name IAS -Number 12 -IssueDate 2017-01-01 -Paragraph 81 -Subparagraph ab -URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=12&date=2017-03-01&anchor=para_81_ab&doctype=Standard -URIDate 2017-03-09 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Name IAS -Number 1 -IssueDate 2017-01-01 -Paragraph 90 -URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=1&date=2017-03-01&anchor=para_90&doctype=Standard -URIDate 2017-03-09 + Details
Name: | ifrs-full_IncomeTaxRelatingToExchangeDifferencesOnTranslationOfOtherComprehensiveIncome
Namespace Prefix: | ifrs-full_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition The amount of income tax relating to amounts recognised in other comprehensive income in relation to hedges of net investments in foreign operations. [Refer: Other comprehensive income] + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Name IAS -Number 12 -IssueDate 2017-01-01 -Paragraph 81 -Subparagraph ab -URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=12&date=2017-03-01&anchor=para_81_ab&doctype=Standard -URIDate 2017-03-09 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Name IAS -Number 1 -IssueDate 2017-01-01 -Paragraph 90 -URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=1&date=2017-03-01&anchor=para_90&doctype=Standard -URIDate 2017-03-09 + Details
Name: | ifrs-full_IncomeTaxRelatingToHedgesOfNetInvestmentsInForeignOperationsOfOtherComprehensiveIncome
Namespace Prefix: | ifrs-full_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition The amount of income tax relating to amounts recognised in other comprehensive income in relation to remeasurements of defined benefit plans. [Refer: Other comprehensive income; Reserve of remeasurements of defined benefit plans; Defined benefit plans [member]] + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Name IAS -Number 12 -IssueDate 2017-01-01 -Paragraph 81 -Subparagraph ab -URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=12&date=2017-03-01&anchor=para_81_ab&doctype=Standard -URIDate 2017-03-09 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Name IAS -Number 1 -IssueDate 2017-01-01 -Paragraph 90 -URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=1&date=2017-03-01&anchor=para_90&doctype=Standard -URIDate 2017-03-09 + Details
Name: | ifrs-full_IncomeTaxRelatingToRemeasurementsOfDefinedBenefitPlansOfOtherComprehensiveIncome
Namespace Prefix: | ifrs-full_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- References No definition available. + Details
Name: | ifrs-full_MiscellaneousEquityAbstract
Namespace Prefix: | ifrs-full_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- References No definition available. + Details
Name: | ifrs-full_OtherProvisionsAbstract
Namespace Prefix: | ifrs-full_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Change In Ownership Of TransAlta Renewables + References No definition available. + Details
Name: | tac_ChangeInOwnershipOfSubsidiary
Namespace Prefix: | tac_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Employee Benefits [Abstract] + References No definition available. + Details
Name: | tac_EmployeeBenefitsAbstract
Namespace Prefix: | tac_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Intercompany Available-For-Sale Investments + References No definition available. + Details
Name: | tac_IntercompanyAvailableForSaleInvestments
Namespace Prefix: | tac_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Details
Name: | ifrs-full_ComponentsOfEquityAxis=ifrs-full_ReserveOfExchangeDifferencesOnTranslationMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | ifrs-full_ComponentsOfEquityAxis=ifrs-full_ReserveOfCashFlowHedgesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | ifrs-full_ComponentsOfEquityAxis=ifrs-full_ReserveOfRemeasurementsOfDefinedBenefitPlansMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | ifrs-full_ComponentsOfEquityAxis=ifrs-full_OtherReservesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |