XML 116 R88.htm IDEA: XBRL DOCUMENT
v3.8.0.1

Significant Events - Sale of Economic Interest in Australian Assets to TransAlta Renewables Inc. (Details) |  |  |  | 1 Months Ended | 5 Months Ended | 7 Months Ended | 12 Months Ended | 19 Months Ended
--- | --- | --- | --- | --- | --- | --- | --- | ---
Aug. 01, 2017 shares | Jul. 31, 2017 | May 07, 2015 CAD shares MW | Jan. 05, 2016 | Dec. 31, 2017 | Nov. 25, 2015 | Dec. 31, 2017 CAD | May 06, 2015 | Jul. 31, 2017
Disclosure of detailed information about business combination [line items] |  |  |  |  |  |  |  |  |
Consideration received |  |  |  |  |  |  | CAD (10,000,000) |  |
Australian Assets |  |  |  |  |  |  |  |  |
Disclosure of detailed information about business combination [line items] |  |  |  |  |  |  |  |  |
Capacity of facility (in megawatts) | MW |  |  | 575 |  |  |  |  |  |
Number of operating assets |  |  | 6 |  |  |  |  |  |
Length of pipeline |  |  | 270 |  |  |  |  |  |
Consideration received |  |  | CAD 1,780,000,000 |  |  |  |  |  |
TransAlta Renewables |  |  |  |  |  |  |  |  |
Disclosure of detailed information about business combination [line items] |  |  |  |  |  |  |  |  |
Proportion of equity participation in subsidiary |  |  |  | 62.00% | 64.00% | 72.80% |  | 70.30% | 59.80%
TransAlta Renewables | Australian Assets |  |  |  |  |  |  |  |  |
Disclosure of detailed information about business combination [line items] |  |  |  |  |  |  |  |  |
Common shares issued (in shares) | shares |  |  | 17,858,423 |  |  |  |  |  |
Share price |  |  | CAD 12.65 |  |  |  |  |  |
Net proceeds on issuance of preferred shares (Note 24) |  |  | 226,000,000 |  |  |  |  |  |
Share issue related cost |  |  | 11,000,000 |  |  |  |  |  |
Effect of share issuance cost on income cost |  |  | 3,000,000 |  |  |  |  |  |
Dividend-equivalent payments |  |  | 1,000,000 |  |  |  |  |  |
TransAlta Renewables | Australian Assets |  |  |  |  |  |  |  |  |
Disclosure of detailed information about business combination [line items] |  |  |  |  |  |  |  |  |
Cash consideration received |  |  | (211,000,000) |  |  |  |  |  |
Value of equity consideration received |  |  | CAD 1,067,000,000 |  |  |  |  |  |
Proportion of equity participation in subsidiary | 64.00% | 59.80% |  |  |  |  |  |  |
Class B shares | TransAlta Renewables | Australian Assets |  |  |  |  |  |  |  |  |
Disclosure of detailed information about business combination [line items] |  |  |  |  |  |  |  |  |
Shares offered for conversion | shares | 26,100,000 |  |  |  |  |  |  |  |
Common shares | TransAlta Renewables | Australian Assets |  |  |  |  |  |  |  |  |
Disclosure of detailed information about business combination [line items] |  |  |  |  |  |  |  |  |
Equity securities received upon conversion of shares | shares | 26,400,000 |  |  |  |  |  |  |  |

X
- Definition The amount of consideration paid or received in respect of both obtaining and losing control of subsidiaries or other businesses. [Refer: Subsidiaries [member]] + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Name IAS -Number 7 -IssueDate 2017-01-01 -Paragraph 40 -Subparagraph a -URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=7&date=2017-03-01&anchor=para_40_a&doctype=Standard -URIDate 2017-03-09 + Details
Name: | ifrs-full_ConsiderationPaidReceived
Namespace Prefix: | ifrs-full_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

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

X
- Definition The number of instruments or interests issued or issuable at acquisition date for equity interests of the acquirer transferred as consideration in a business combination. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Name IFRS -Number 3 -IssueDate 2017-01-01 -Paragraph B64 -Subparagraph f -Clause iv -URI http://eifrs.ifrs.org/eifrs/XBRL?type=IFRS&num=3&date=2017-03-01&anchor=para_B64_f_iv&doctype=Appendix&seq=2 -URIDate 2017-03-09 + Details
Name: | ifrs-full_NumberOfInstrumentsOrInterestsIssuedOrIssuable
Namespace Prefix: | ifrs-full_
Data Type: | xbrli:decimalItemType
Balance Type: | na
Period Type: | instant

X
- Definition The portion of consideration paid or received, consisting of cash and cash equivalents, in respect of both obtaining and losing control of subsidiaries or other businesses. [Refer: Subsidiaries [member]; Cash and cash equivalents; Consideration paid (received)] + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Name IAS -Number 7 -IssueDate 2017-01-01 -Paragraph 40 -Subparagraph b -URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=7&date=2017-03-01&anchor=para_40_b&doctype=Standard -URIDate 2017-03-09 + Details
Name: | ifrs-full_PortionOfConsiderationPaidReceivedConsistingOfCashAndCashEquivalents
Namespace Prefix: | ifrs-full_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition The cash inflow from issuing shares. + References Reference 1: http://www.xbrl.org/2003/role/exampleRef -Name IAS -Number 7 -IssueDate 2017-01-01 -Paragraph 17 -Subparagraph a -URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=7&date=2017-03-01&anchor=para_17_a&doctype=Standard -URIDate 2017-03-09 + Details
Name: | ifrs-full_ProceedsFromIssuingShares
Namespace Prefix: | ifrs-full_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition The amount of cost related to the issuance of shares. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Name IAS -Number 1 -IssueDate 2017-01-01 -Paragraph 106 -Subparagraph d -URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=1&date=2017-03-01&anchor=para_106_d&doctype=Standard -URIDate 2017-03-09 + Details
Name: | ifrs-full_ShareIssueRelatedCost
Namespace Prefix: | ifrs-full_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Capacity Of Generation Units, Power + References No definition available. + Details
Name: | tac_CapacityOfPowerGenerationAssetsPower
Namespace Prefix: | tac_
Data Type: | num:powerItemType
Balance Type: | na
Period Type: | instant

X
- Definition Dividend-Equivalent Payments + References No definition available. + Details
Name: | tac_DividendEquivalentPayments
Namespace Prefix: | tac_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Equity securities received upon conversion of shares + References No definition available. + Details
Name: | tac_Equitysecuritiesreceiveduponconversionofshares
Namespace Prefix: | tac_
Data Type: | xbrli:sharesItemType
Balance Type: | na
Period Type: | instant

X
- Definition Length Of Pipeline + References No definition available. + Details
Name: | tac_LengthOfPipeline
Namespace Prefix: | tac_
Data Type: | xbrli:pureItemType
Balance Type: | na
Period Type: | instant

X
- Definition Number Of Operating Assets + References No definition available. + Details
Name: | tac_NumberOfOperatingAssets
Namespace Prefix: | tac_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | instant

X
- Definition Portion Of Consideration Paid (Received) Consisting Of Equity Interests + References No definition available. + Details
Name: | tac_PortionOfConsiderationPaidReceivedConsistingOfEquityInterests
Namespace Prefix: | tac_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Proportion Of Equity Participation In Subsidiary + References No definition available. + Details
Name: | tac_ProportionOfEquityParticipationInSubsidiary
Namespace Prefix: | tac_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition Share Issue Related Cost, Effect Of Income Tax Recovery + References No definition available. + Details
Name: | tac_ShareIssueRelatedCostEffectOnIncomeTaxRecovery
Namespace Prefix: | tac_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Share Price At Issuance + References No definition available. + Details
Name: | tac_SharePriceAtIssuance
Namespace Prefix: | tac_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Shares offered for conversion + References No definition available. + Details
Name: | tac_Sharesofferedforconversion
Namespace Prefix: | tac_
Data Type: | xbrli:sharesItemType
Balance Type: | na
Period Type: | instant

X
- Details
Name: | ifrs-full_BusinessCombinationsAxis=tac_AustralianAssetsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | ifrs-full_SignificantInvestmentsInSubsidiariesAxis=tac_TransAltaRenewablesInc.Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | ifrs-full_CounterpartiesAxis=tac_TransAltaRenewablesInc.Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | ifrs-full_ClassesOfOrdinarySharesAxis=tac_ClassBsharesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | ifrs-full_ClassesOfOrdinarySharesAxis=tac_CommonsharesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |