Realized Gain (Loss) on Derivative Instruments Held for Trading Purposes, Net

No definition available.

Name:	trp_RealizedGainLossonDerivativeInstrumentsHeldforTradingPurposesNet
Namespace Prefix:	trp_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Unrealized Gain (Loss) on Derivative Instruments Held for Trading Purposes, Net

+ References

No definition available.

+ Details

Name:	trp_UnrealizedGainLossonDerivativeInstrumentsHeldforTradingPurposesNet
Namespace Prefix:	trp_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Amount of increase (decrease) in the fair value of derivatives recognized in the income statement.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 4A
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=64837297&loc=SL5618551-113959

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 4C
-Subparagraph (a),(c),(d),(e)
-URI http://asc.fasb.org/extlink&oid=64837297&loc=SL5624171-113959

+ Details

Name:	us-gaap_DerivativeGainLossOnDerivativeNet
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

+ Details

Name:	us-gaap_DerivativeLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

The amount of gain reclassified into earnings in the period when cash flow hedge is discontinued because it is probable that the original forecasted transactions will not occur by the end of the original period or an additional two month time period.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 30
-Section 50
-Paragraph 1
-Subparagraph (e)
-URI http://asc.fasb.org/extlink&oid=35736893&loc=d3e80748-113994

+ Details

Name:	us-gaap_GainOnDiscontinuationOfCashFlowHedgeDueToForecastedTransactionProbableOfNotOccurring
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

The amount of loss reclassified into earnings in the period when cash flow hedge is discontinued because it is probable that the original forecasted transactions will not occur by the end of the original period or an additional two month time period.

+ References

+ Details

Name:	us-gaap_LossOnDiscontinuationOfCashFlowHedgeDueToForecastedTransactionProbableOfNotOccurring
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Details

Name:	us-gaap_DerivativeInstrumentRiskAxis=us-gaap_CommodityContractMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_HedgingDesignationAxis=us-gaap_DesignatedAsHedgingInstrumentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DerivativeInstrumentRiskAxis=us-gaap_ForeignExchangeContractMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DerivativeInstrumentRiskAxis=us-gaap_InterestRateContractMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis=trp_U.S.NortheastMerchantPowerAssetsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

RISK MANAGEMENT AND FINANCIAL INSTRUMENTS - Unrealized and Realized (Losses)/Gains (Details) - CAD CAD in Millions	3 Months Ended	12 Months Ended
	Mar. 31, 2016	Dec. 31, 2016	Dec. 31, 2015
Commodities
Derivative [Line Items]
Amount of unrealized gains/(losses) in the year		CAD 123	CAD (37)
Amount of realized (losses)/gains in the year		(204)	(151)
Commodities \| Derivative instruments in hedging relationships
Derivative [Line Items]
Amount of realized (losses)/gains in the year		(167)	(179)
Foreign exchange
Derivative [Line Items]
Amount of unrealized gains/(losses) in the year		25	(21)
Amount of realized (losses)/gains in the year		62	(112)
Foreign exchange \| Derivative instruments in hedging relationships
Derivative [Line Items]
Amount of realized (losses)/gains in the year		(101)	0
Interest rate \| Derivative instruments in hedging relationships
Derivative [Line Items]
Amount of realized (losses)/gains in the year		CAD 4	CAD 8
U.S. Northeast Merchant Power Assets
Derivative [Line Items]
Loss on cash flow hedge	CAD 49
Gain on cash flow hedge	CAD 7