VARIABLE INTEREST ENTITIES (Narrative) (Details) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2016	Dec. 31, 2015
Midcoast Operating [Member]
Variable Interest Entity [Line Items]
Ownership interest (in percentage)	51.60%
Ownership interest by Noncontrolling owners (in percentage)	48.40%
Midcoast Operating [Member] \| Variable Interest Entity, Primary Beneficiary [Member]
Variable Interest Entity [Line Items]
Ownership interest (in percentage)	51.60%
Ownership interest by Noncontrolling owners (in percentage)	48.40%
Midcoast Energy Partners [Member] \| Variable Interest Entity, Primary Beneficiary [Member]
Variable Interest Entity [Line Items]
Ownership interest (in percentage)	51.90%
VIE assets	$ 4,913.9	$ 5,227.2
VIE liabilities	1,138.1	1,220.7
Enbridge Energy Limited Partnership [Member] \| Variable Interest Entity, Primary Beneficiary [Member]
Variable Interest Entity [Line Items]
VIE assets	11,386.6	11,074.9
VIE liabilities	759.8	998.2
North Dakota Pipeline Company [Member] \| Variable Interest Entity, Primary Beneficiary [Member]
Variable Interest Entity [Line Items]
VIE assets	1,045.1	1,746.3
VIE liabilities	$ 53.0	$ 84.8
North Dakota Pipeline Company [Member] \| Capital Unit, Class A [Member] \| Variable Interest Entity, Primary Beneficiary [Member]
Variable Interest Entity [Line Items]
Ownership interest (in percentage)	100.00%
North Dakota Pipeline Company [Member] \| Capital Unit, Class B [Member] \| Variable Interest Entity, Primary Beneficiary [Member]
Variable Interest Entity [Line Items]
Ownership interest (in percentage)	62.50%
North Dakota Pipeline Company [Member] \| Capital Unit, Class B [Member] \| Williston Basin Pipeline LLC [Member]
Variable Interest Entity [Line Items]
Ownership interest (in percentage)	37.50%
Series Lakehead and Series AC [Member] \| Enbridge Energy Limited Partnership [Member] \| General And Limited Partner Interest [Member] \| Variable Interest Entity, Primary Beneficiary [Member]
Variable Interest Entity [Line Items]
Ownership interest (in percentage)	100.00%
Series EA and Series ME [Member] \| Enbridge Energy Limited Partnership [Member] \| General And Limited Partner Interest [Member] \| Variable Interest Entity, Primary Beneficiary [Member]
Variable Interest Entity [Line Items]
Ownership interest (in percentage)	25.00%
Series EA and Series ME [Member] \| Enbridge Energy Limited Partnership [Member] \| General Partner [Member]
Variable Interest Entity [Line Items]
Ownership interest (in percentage)	75.00%

The equity interest of noncontrolling shareholders, partners or other equity holders in consolidated entity.

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- Definition

The number of units or percentage investment held in the subsidiary by the limited liability company or limited partnership.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 946
-SubTopic 320
-Section S99
-Paragraph 9
-URI http://asc.fasb.org/extlink&oid=50485924&loc=d3e611443-123010

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- Definition

The carrying amount of the consolidated Variable Interest Entity's assets included in the reporting entity's statement of financial position.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 810
-SubTopic 10
-Section 50
-Paragraph 3
-Subparagraph (bb)
-URI http://asc.fasb.org/extlink&oid=64801991&loc=d3e5710-111685

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The carrying amount of the consolidated Variable Interest Entity's liabilities included in the reporting entity's statement of financial position.

+ References

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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

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