ACQUISITIONS (Details) - USD ($) $ in Millions	1 Months Ended	12 Months Ended
	Feb. 27, 2015	Dec. 31, 2016	Dec. 31, 2015
Business Acquisition [Line Items]
Restricted cash		$ 24.5	$ 37.6
Midcoast Operating [Member]
Business Acquisition [Line Items]
Ownership in Midcoast Operating (in percentage)		48.40%
Ownership in Midcoast Operating held by MEP (in percentage)		51.60%
NGR Acquisition [Member]
Business Acquisition [Line Items]
Payments to acquire interest in affiliate	$ 85.0
Price transferred to escrow agent	20.0
Restricted cash			6.0
Earnout period (in years)		5 years
Maximum contingent consideration	17.0	$ 17.0
Accretion of contingent consideration			0.3
Other assets, net	$ 17.0		$ 6.0
Gain recognized on escrow refund		3.0
Gain recognized on liability reversal		2.6
Contingent liability reversed		$ 2.3