Name:	tcp_CapitalUnitsPercentageOfSubsidiaryDistributionsSubjectToRightsOfHolderToReceivePartnersCapitalAccountDistributionsAtSpecifiedPercentageInExcessOfSpecifiedAmount
Namespace Prefix:	tcp_
Data Type:	num:percentItemType
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Represents, for rights of the holder of capital units to receive partners capital account distributions, the initial percentage (100%) to be applied during a specified period to 30 percent of subsidiary distributions in excess of a specified amount, as defined.

No definition available.

Name:	tcp_CapitalUnitsRightsOfHolderToReceivePartnersCapitalAccountDistributionsInitialEffectivePercentageAppliedToSubsidiaryDistributionsInExcessOfSpecifiedAmount
Namespace Prefix:	tcp_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

Represents, for rights of the holder of capital units to receive partners capital account distributions, the threshold of subsidiary distributions for payment to the holder, prorated in the year of issuance.

No definition available.

Name:	tcp_CapitalUnitsRightsOfHolderToReceivePartnersCapitalAccountDistributionsThresholdOfSubsidiaryDistributionsForPaymentInitialProratedAmount
Namespace Prefix:	tcp_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
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- References

No definition available.

Name:	us-gaap_DistributionsMadeToMembersOrLimitedPartnersAbstract
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- References

No definition available.

Name:	us-gaap_EarningsPerUnitAbstract
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The portion of profit or loss for the period which is attributable to the parent.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 225
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SX 210.5-03.20)
-URI http://asc.fasb.org/extlink&oid=63488584&loc=d3e20235-122688

Name:	us-gaap_IncomeLossAttributableToParent
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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

Amount of cash or stock or unit payment to a limited liability corporation managing member or limited partnership general partner after the end of the accounting period.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 260
-SubTopic 10
-Section 45
-Paragraph 73
-URI http://asc.fasb.org/extlink&oid=6926462&loc=SL5163674-159010

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 260
-SubTopic 10
-Section 45
-Paragraph 72
-URI http://asc.fasb.org/extlink&oid=6926462&loc=SL5163672-159010

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 260
-SubTopic 10
-Section 55
-Paragraph 103
-URI http://asc.fasb.org/extlink&oid=65015998&loc=SL5199526-159011

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

Aggregate amount of net income allocated to general partners.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section S99
-Paragraph 5
-Subparagraph (SAB Topic 4.F)
-URI http://asc.fasb.org/extlink&oid=27012166&loc=d3e187171-122770

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

Aggregate amount of net income allocated to limited partners.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section S99
-Paragraph 5
-URI http://asc.fasb.org/extlink&oid=27012166&loc=d3e187171-122770

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

Per unit of ownership amount after tax of income (loss) available to limited partnership (LP) unit-holder and units that would have been outstanding assuming the issuance of limited partner units for dilutive potential units outstanding.

Name:	us-gaap_NetIncomeLossNetOfTaxPerOutstandingLimitedPartnershipUnitDiluted
Namespace Prefix:	us-gaap_
Data Type:	num:perShareItemType
Balance Type:	na
Period Type:	duration

Per unit of ownership amount after tax of income (loss) available to outstanding limited partnership (LP) unit-holder.

Name:	us-gaap_NetIncomeLossPerOutstandingLimitedPartnershipUnitBasicNetOfTax
Namespace Prefix:	us-gaap_
Data Type:	num:perShareItemType
Balance Type:	na
Period Type:	duration

Weighted average number of limited partnership units outstanding determined by relating the portion of time within a reporting period that limited partnership units have been outstanding to the total time in that period.

Name:	us-gaap_WeightedAverageLimitedPartnershipUnitsOutstanding
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration

Name:	us-gaap_WeightedAverageLimitedPartnershipUnitsOutstandingDiluted
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration

Name:	us-gaap_LimitedPartnersCapitalAccountByClassAxis=tcp_LimitedPartnerCommonUnitMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	dei_LegalEntityAxis=tcp_GasTransmissionNorthwestLLCMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	us-gaap_LimitedPartnersCapitalAccountByClassAxis=tcp_LimitedPartnerClassBUnitMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	us-gaap_RelatedPartyTransactionsByRelatedPartyAxis=tcp_TransCanadaCorporationAndSubsidiariesExcludingGeneralPartnerSubsidiariesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: