Represents the number of financial institutions (Managers) acting as sales agents.

No definition available.

Name:	tclp_NumberOfFinancialInstitutionsActingAsSalesAgents
Namespace Prefix:	tclp_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Definition

Represents the number of sales agents (Managers) required to be in agreement with the entity for a sale of equity other than by means of ordinary brokers' transactions on a stock exchange at market prices or in block transactions.

+ References

No definition available.

+ Details

Name:	tclp_OtherEquitySalesMethodNumberOfManagersInAgreement
Namespace Prefix:	tclp_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Definition

The number of units sold in a public offering of each class of partners' capital account pursuant to the exercise of the underwriters' option to purchase additional common units. Units represent shares of ownership of the general, limited, and preferred partners.

+ References

No definition available.

+ Details

Name:	tclp_PartnersCapitalAccountUnitsSoldInPublicOfferingPursuantToExerciseOfUnderwritersOption
Namespace Prefix:	tclp_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration

- Definition

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

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-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

+ Details

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

- Definition

The number of units or percentage investment held by one or more members or limited partners of the LLC or LP.

+ References

+ Details

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

- Definition

The number of limited partner units outstanding.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 272

-SubTopic 10

-Section 50

-Paragraph 1

-URI http://asc.fasb.org/extlink&oid=6373374&loc=d3e70434-108055

Reference 2: 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

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Staff Accounting Bulletin (SAB)

-Number Topic 4

-Section F

+ Details

Name:	us-gaap_LimitedPartnersCapitalAccountUnitsOutstanding
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	instant

- Definition

Total contributions made by each class of partners (i.e., general, limited and preferred partners).

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 04

-Article 3

Reference 2: 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

+ Details

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

- Definition

Monetary value of the issuance of new units of limited partnership interest in a public offering.

+ References

+ Details

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

- Definition

Monetary value of the issuance of new units of limited partnership interest in a public offering, net of offering costs. This is a parenthetical disclosure.

+ References

+ Details

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

- Definition

The number of units sold in a public offering of each class of partners' capital account. Units represent shares of ownership of the general, limited, and preferred partners.

+ References

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

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 04

-Paragraph 16

-Subparagraph a, b

-Article 6

+ Details

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

- Definition

The cash outflow for cost incurred directly with the issuance of an equity security.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Glossary Financing Activities

-URI http://asc.fasb.org/extlink&oid=6513228

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 230

-SubTopic 10

-Section 45

-Paragraph 15

-URI http://asc.fasb.org/extlink&oid=31042434&loc=d3e3291-108585

+ Details

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

- Details

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

- Definition

Amount per share or per unit of equity securities issued by non-development stage entity.

+ References

No definition available.

+ Details

Name:	us-gaap_SharesIssuedPricePerShare
Namespace Prefix:	us-gaap_
Data Type:	num:perShareItemType
Balance Type:	na
Period Type:	instant

- Details

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

- Details

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

- Details

Name:	tclp_SaleOfLimitedPartnershipUnitsAxis=tclp_AtMarketEquityIssuanceProgramMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	tclp_SaleOfLimitedPartnershipUnitsAxis=tclp_SaleOfLimitedPartnershipUnitsPublicOfferingMay2013Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_PartnerTypeOfPartnersCapitalAccountAxis=us-gaap_LimitedPartnerMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

PARTNERS' EQUITY (Details) (USD $) In Millions, except Share data, unless otherwise specified	12 Months Ended	0 Months Ended		12 Months Ended		1 Months Ended
	Dec. 31, 2014	May 22, 2013	May 22, 2013	Dec. 31, 2013	Dec. 31, 2012	Aug. 31, 2014 Institution
Partners' Equity
Number of common units	63,600,000			62,300,000	53,500,000
Common Units (Limited Partners)
Partners' Equity
Number of common units	63,561,546			62,327,766	53,472,766
Ownership interest in the Partnership (as a percent)	98.00%
TC PipeLines GP, Inc. \| Common Units (Limited Partners)
Partners' Equity
Number of common units	5,797,106
TC PipeLines GP, Inc. \| General Partner
Partners' Equity
Ownership interest in the Partnership (as a percent)	2.00%	2.00%	2.00%	2.00%	2.00%
TC PipeLines GP, Inc. \| Common units and General Partner interest combined
Partners' Equity
Ownership interest in the Partnership (as a percent)	10.90%			11.10%	12.60%
TransCanada \| Common Units (Limited Partners)
Partners' Equity
Number of common units	11,287,725
Ownership interest in the Partnership (as a percent)	17.40%
ATM Equity Issuance Program \| Common Units (Limited Partners)
Partners' Equity
Number of financial institutions						5
Units sold	1,300,000
Sales agent commissions	1
Net proceeds from public offering of common units	72
ATM Equity Issuance Program \| TC PipeLines GP, Inc. \| General Partner
Partners' Equity
Equity contribution	1
ATM Equity Issuance Program \| Maximum \| Expected \| Common Units (Limited Partners)
Partners' Equity
Gross proceeds from sale of common units						200
ATM Equity Issuance Program \| Minimum \| Common Units (Limited Partners)
Partners' Equity
Number of managers to agree with equity sale method						1
Equity Issuance, May 2013 \| Common Units (Limited Partners)
Partners' Equity
Units sold		8,855,000
Units sold in public offering pursuant to exercise of underwriters' option		1,155,000
Price per common unit in public offering		43.85	43.85
Gross proceeds from sale of common units		388
Net proceeds from public offering of common units		373
Equity Issuance, May 2013 \| TC PipeLines GP, Inc. \| General Partner
Partners' Equity
Equity contribution		8