Name:	tcp_CapitalUnitsPercentageOfSubsidiaryDistributionsSubjectToRightsOfHolderToReceivePartnersCapitalAccountDistributionsAtSpecifiedPercentageInExcessOfSpecifiedAmount
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 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 initial percentage to be applied during a specified period two to subsidiary distributions in excess of a specified amount, as defined.

No definition available.

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

Represents the amount of reduction of the rights of the holder of capital units to receive partner's capital account distributions.

No definition available.

Name:	tcp_CapitalUnitsRightsOfHolderToReceivePartnersCapitalAccountDistributionsReductionOfSubsidiaryDistributions
Namespace Prefix:	tcp_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
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
Period Type:	duration

Percentage of reduction in distributions payable to capital units.

No definition available.

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

Percentage investment held by the managing member or general partner of the limited liability company (LLC) or limited partnership (LP).

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 272
-SubTopic 10
-Section 50
-Paragraph 3
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=6373374&loc=d3e70478-108055

Name:	us-gaap_LimitedLiabilityCompanyLLCOrLimitedPartnershipLPManagingMemberOrGeneralPartnerOwnershipInterest
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

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.

No definition available.

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

Name:	srt_OwnershipAxis=tcp_TCPipelinesLpMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	dei_LegalEntityAxis=tcp_TCPipelinesGPInc.Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

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

Name:	us-gaap_RelatedPartyTransactionsByRelatedPartyAxis=tcp_TransCanadaCorporationAndSubsidiariesExcludingGeneralPartnerSubsidiariesMember
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: