NET INCOME PER LIMITED PARTNER UNIT (Basic and Diluted Net Income Per Limited Partner Unit) (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Continuing operations:
Net income from continuing operations	$ 196.0	$ (543.5)	$ 607.3	$ (100.1)
Less: Net income attributable to: Noncontrolling interest	102.9	(182.3)	280.6	(16.9)
Series 1 preferred unit distributions	0.0	22.5	29.0	67.5
Accretion of discount on Series 1 preferred units	0.0	1.2	8.5	3.5
Net income (loss) attributable to general and limited partner interests in Enbridge Energy Partners, L.P. – continuing operations	93.1	(384.9)	289.2	(154.2)
Distributions:
Incentive distributions	(3.7)	(5.3)	(11.1)	(15.7)
Distributed earnings attributed to Class D and Class E units	(13.2)	(59.6)	(39.7)	(178.7)
Total distributed earnings attributed to our common units and i-units	(147.7)	(204.1)	(441.0)	(608.7)
Total distributed earnings	(160.9)	(263.7)	(480.7)	(787.4)
Overdistributed earnings	(67.8)	(648.6)	(191.5)	(941.6)
Discontinued operations:
Net loss	0.0	(31.1)	(56.8)	(124.4)
Less: Net loss attributable to Noncontrolling interest	0.0	(9.6)	(18.8)	(35.9)
Net loss attributable to general and limited partner interests in Enbridge Energy Partners, L.P. - discontinued operations	$ 0.0	$ (21.5)	$ (38.0)	$ (88.5)
Weighted average common units and i-units outstanding (in shares)	421,000,000	349,100,000	391,600,000	347,000,000
Basic and diluted earnings per unit:
Distributed earnings per common unit and i-unit - continuing operations (in dollars per share)	$ 0.35	$ 0.58	$ 1.13	$ 1.75
Overdistributed earnings per common unit and i-unit (in dollars per share)	(0.16)	(1.83)	(0.48)	(2.66)
Net income per common unit and i-unit (basic and diluted) - continuing operations (in dollars per share)	0.19	(1.25)	0.65	(0.91)
Net loss per common unit and i-unit (basic and diluted) - discontinued operations (in dollars per share)	0.00	(0.06)	(0.10)	(0.25)
Net income per common unit and i-unit (basic and diluted) (in dollars per share)	$ 0.19	$ (1.31)	$ 0.55	$ (1.16)
Class D and Class E Units [Member]
Distributions:
Distributed earnings attributed to Class D and Class E units	$ (6.3)	$ (49.1)	$ (19.0)	$ (147.3)
General Partner [Member]
Distributions:
Distributed earnings attributed to our General Partner	$ (3.2)	$ (5.2)	$ (9.6)	$ (15.7)
Preferred Stock [Member]
Basic and diluted earnings per unit:
Anti-dilutive Preferred Units excluded (in shares)			43,201,310
Class E Units [Member]
Basic and diluted earnings per unit:
Anti-dilutive Preferred Units excluded (in shares)	18,114,975			18,114,975
Class D Units [Member]
Basic and diluted earnings per unit:
Anti-dilutive Preferred Units excluded (in shares)		66,100,000	66,100,000	66,100,000