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

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

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-Topic 272

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

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 505

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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.

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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

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

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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

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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.

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No definition available.

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PARTNERS' EQUITY (Details) - USD ($)		3 Months Ended		9 Months Ended
PARTNERS' EQUITY (Details) - USD ($)	Apr. 02, 2015	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Partners' Equity
Equity contribution				$ 2,000,000
General Partner
Partners' Equity
Equity contribution				$ 2,000,000
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%
ATM Equity Issuance Program \| Common units
Partners' Equity
Units sold				396,205
Net proceeds from public offering of common units				$ 25,000,000
Sales agent commissions				256,000
ATM Equity Issuance Program \| TC PipeLines GP, Inc. \| General Partner
Partners' Equity
Equity contribution				$ 1,000,000