DEBT (MEP Private Debt Issuance) (Details) - Jun. 30, 2015 - Senior Notes [Member] - Midcoast Energy Partners [Member] - USD ($) $ in Millions	Total
Debt Instrument [Line Items]
Debt, face amount	$ 400.0
3.560% Series A Senior Notes due 2019 [Member]
Debt Instrument [Line Items]
Debt, face amount	$ 75.0
Maturity date	Dec. 31, 2019
Interest Rate (in percentage)	3.56%
4.040% Series B Senior Notes due 2021 [Member]
Debt Instrument [Line Items]
Debt, face amount	$ 175.0
Maturity date	Dec. 31, 2021
Interest Rate (in percentage)	4.04%
4.420% Series C Senior Notes due 2024 [Member]
Debt Instrument [Line Items]
Debt, face amount	$ 150.0
Maturity date	Dec. 31, 2024
Interest Rate (in percentage)	4.42%

Face (par) amount of debt instrument at time of issuance.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 835

-SubTopic 30

-Section 55

-Paragraph 8

-URI http://asc.fasb.org/extlink&oid=34725769&loc=d3e28878-108400

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 835

-SubTopic 30

-Section 45

-Paragraph 2

-URI http://asc.fasb.org/extlink&oid=6451184&loc=d3e28551-108399

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- Definition

Contractual interest rate for funds borrowed, under the debt agreement.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.5-02.22(a)(1))

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- Definition

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.

+ References

No definition available.

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- Definition

Date when the debt instrument is scheduled to be fully repaid, in CCYY-MM-DD format.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.5-02.22(a)(2))

-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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