Percentage of maximum transportation interim rate increase (decrease) allowed while waiting final decision of regulatory agency.

No definition available.

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

Percentage of maximum transportation requested rate increase (decrease) with regulatory agency.

No definition available.

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

Percentage of maximum transportation requested rate increase (decrease) with regulatory agency with effective April 1, 2020.

No definition available.

Name:	tcp_MaximumTransportationRequestedRateIncreaseDecreasePercentageEffectiveApril12020
Namespace Prefix:	tcp_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

Percentage of maximum transportation requested rate increase (decrease) with regulatory agency with effective March 1, 2019.

No definition available.

Name:	tcp_MaximumTransportationRequestedRateIncreaseDecreasePercentageEffectiveMarch12019
Namespace Prefix:	tcp_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

Number of phases in which percentage of public utility's approved rate increase (decrease) by regulatory agency is implemented

No definition available.

Name:	tcp_PublicUtilitiesApprovedRateIncreaseDecreaseNumberOfPhases
Namespace Prefix:	tcp_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

Percentage of public utility's approved rate increase (decrease) by regulatory agency.

No definition available.

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

No definition available.

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

Name:	us-gaap_PublicUtilitiesRegulatoryProceedingAxis=tcp_Iroquois2019SettlementMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	us-gaap_RegulatoryAgencyAxis=tcp_FederalEnergyRegulatoryCommissionMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	us-gaap_PublicUtilitiesRegulatoryProceedingAxis=tcp_TuscaroraStipulationAndAgreementOfSettlementMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	us-gaap_PublicUtilitiesRegulatoryProceedingAxis=tcp_NorthernBorderSettlementMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

REGULATORY (Details) - FERC - item	Feb. 28, 2029	Apr. 04, 2019	Mar. 15, 2019	Feb. 28, 2019
Iroquois
REGULATORY
Reduction of existing maximum system rates (as a percent)	6.50%			6.50%
Number phases of reduction of rates				2
Reduction of existing maximum system rates effective March 1,2019 (as a percent)				3.25%
Reduction of existing maximum system rates effective April 1,2020 (as a percent)				3.25%
Tuscarora Settlement
REGULATORY
Reduction of existing maximum system rates (as a percent)			1.70%
Additional decrease of unit rate (as a percent)			10.80%
Northern Border
REGULATORY
Decrease in rate (as a percent)		2.00%