DERIVATIVE FINANCIAL INSTRUMENTS AND HEDGING ACTIVITIES (Effect of Derivative Instruments on Consolidated Statements of Financial Position) (Details) - USD ($) $ in Millions		Sep. 30, 2015	Dec. 31, 2014
Derivatives, Fair Value [Line Items]
Asset Derivatives		$ 193.4	$ 279.1
Liability Derivatives		(551.2)	(411.6)
Cash collateral held		16.2	28.4
Derivatives Designated As Hedging Instruments [Member]
Derivatives, Fair Value [Line Items]
Asset Derivatives	[1]	7.4	28.2
Liability Derivatives	[1]	(487.4)	(343.0)
Derivatives Designated As Hedging Instruments [Member] | Other Current Assets [Member] | Commodity Contract [Member]
Derivatives, Fair Value [Line Items]
Asset Derivatives	[1]	$ 7.4	$ 26.1
Liability Derivatives	[1]
Derivatives Designated As Hedging Instruments [Member] | Other Assets [Member] | Commodity Contract [Member]
Derivatives, Fair Value [Line Items]
Asset Derivatives	[1]		$ 2.1
Liability Derivatives	[1]
Derivatives Designated As Hedging Instruments [Member] | Accounts Payable and Other [Member] | Interest Rate Contracts [Member]
Derivatives, Fair Value [Line Items]
Asset Derivatives	[1]
Liability Derivatives	[1]	$ (319.4)	$ (241.0)
Derivatives Designated As Hedging Instruments [Member] | Other Long-term Liabilities [Member] | Interest Rate Contracts [Member]
Derivatives, Fair Value [Line Items]
Asset Derivatives	[1]
Liability Derivatives	[1]	$ (168.0)	$ (102.0)
Derivatives Not Designated As Hedging Instruments [Member]
Derivatives, Fair Value [Line Items]
Asset Derivatives		186.0	250.9
Liability Derivatives		(63.8)	(68.6)
Derivatives Not Designated As Hedging Instruments [Member] | Other Current Assets [Member] | Commodity Contract [Member]
Derivatives, Fair Value [Line Items]
Asset Derivatives		$ 130.4	$ 159.4
Liability Derivatives
Derivatives Not Designated As Hedging Instruments [Member] | Other Assets [Member] | Commodity Contract [Member]
Derivatives, Fair Value [Line Items]
Asset Derivatives		$ 55.6	$ 91.2
Liability Derivatives
Derivatives Not Designated As Hedging Instruments [Member] | Accounts Payable and Other [Member] | Commodity Contract [Member]
Derivatives, Fair Value [Line Items]
Asset Derivatives	[2]
Liability Derivatives	[2]	$ (42.0)	$ (46.0)
Cash collateral held		$ 16.2	$ 28.4
Derivatives Not Designated As Hedging Instruments [Member] | Other Long-term Liabilities [Member] | Commodity Contract [Member]
Derivatives, Fair Value [Line Items]
Asset Derivatives
Liability Derivatives		$ (21.8)	$ (22.6)
Derivatives Not Designated As Hedging Instruments [Member] | Due from General Partner and Affiliates [Member] | Commodity Contract [Member]
Derivatives, Fair Value [Line Items]
Asset Derivatives			$ 0.3
Liability Derivatives

[1] Includes items currently designated as hedging instruments. Excludes the portion of de-designated hedges which may have a component remaining in AOCI.

[2] Liability derivatives exclude $16.2 million and $28.4 million held of cash collateral at September 30, 2015 and December 31, 2014, respectively.