DERIVATIVE FINANCIAL INSTRUMENTS AND HEDGING ACTIVITIES (Quantitative Information about Level 3 Fair Value Measurements) (Details) $ in Millions		12 Months Ended
		Dec. 31, 2016 USD ($) $ / Gallon-gal $ / MillionsofBTU-MMBTU $ / Barrel-bbl $ / MillionBarrels-MMBbls		Dec. 31, 2015 USD ($) $ / Gallon-gal $ / MillionsofBTU-MMBTU $ / Barrel-bbl
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Assets and liabilities accounted for at fair value on a recurring basis	[1]	$ (173.7)		$ (57.9)
Level 3 [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Assets and liabilities accounted for at fair value on a recurring basis		(4.5)		103.8
Credit Valuation Adjustments		0.1		(0.3)
Commodity Contracts - Financial [Member] | Natural Gas [Member] | Level 3 [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Assets and liabilities accounted for at fair value on a recurring basis		4.7		0.3
Commodity Contracts - Financial [Member] | NGL [Member] | Level 3 [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Assets and liabilities accounted for at fair value on a recurring basis		$ (4.8)		$ 8.6
Commodity Contracts - Financial [Member] | Maximum [Member] | Natural Gas [Member] | Level 3 [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Forward Price | $ / MillionsofBTU-MMBTU		3.93	[2]	3.07	[3]
Commodity Contracts - Financial [Member] | Maximum [Member] | NGL [Member] | Level 3 [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Forward Price | $ / Gallon-gal		1.23	[2]	0.93	[3]
Commodity Contracts - Financial [Member] | Minimum [Member] | Natural Gas [Member] | Level 3 [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Forward Price		3.18	[2]	2.27	[3]
Commodity Contracts - Financial [Member] | Minimum [Member] | NGL [Member] | Level 3 [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Forward Price | $ / Gallon-gal		0.27	[2]	0.16	[3]
Commodity Contracts - Financial [Member] | Weighted Average [Member] | Natural Gas [Member] | Level 3 [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Forward Price | $ / MillionsofBTU-MMBTU		3.58	[2]	2.64	[3]
Commodity Contracts - Financial [Member] | Weighted Average [Member] | NGL [Member] | Level 3 [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Forward Price | $ / Gallon-gal		0.64	[2]	0.41	[3]
Commodity Contracts - Physical [Member] | Natural Gas [Member] | Level 3 [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Assets and liabilities accounted for at fair value on a recurring basis		$ 0.7		$ (2.5)	[4]
Commodity Contracts - Physical [Member] | Crude Oil [Member] | Level 3 [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Assets and liabilities accounted for at fair value on a recurring basis		(1.2)		0.0
Commodity Contracts - Physical [Member] | NGL [Member] | Level 3 [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Assets and liabilities accounted for at fair value on a recurring basis		$ 3.1		$ 3.1
Commodity Contracts - Physical [Member] | Maximum [Member] | Natural Gas [Member] | Level 3 [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Forward Price | $ / MillionsofBTU-MMBTU		4.16	[2]	3.44	[3]
Commodity Contracts - Physical [Member] | Maximum [Member] | Crude Oil [Member] | Level 3 [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Forward Price | $ / Barrel-bbl		55.62	[2]	38.41	[3]
Commodity Contracts - Physical [Member] | Maximum [Member] | NGL [Member] | Level 3 [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Forward Price | $ / Gallon-gal		1.31	[2]	1.2	[3]
Commodity Contracts - Physical [Member] | Minimum [Member] | Natural Gas [Member] | Level 3 [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Forward Price | $ / MillionsofBTU-MMBTU		2.72	[2]	2.08	[3]
Commodity Contracts - Physical [Member] | Minimum [Member] | Crude Oil [Member] | Level 3 [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Forward Price | $ / Barrel-bbl		39.21	[2]	26.5	[3]
Commodity Contracts - Physical [Member] | Minimum [Member] | NGL [Member] | Level 3 [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Forward Price | $ / Gallon-gal		0.27	[2]	0.16	[3]
Commodity Contracts - Physical [Member] | Weighted Average [Member] | Natural Gas [Member] | Level 3 [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Forward Price | $ / MillionsofBTU-MMBTU		3.49	[2]	2.33	[3]
Commodity Contracts - Physical [Member] | Weighted Average [Member] | Crude Oil [Member] | Level 3 [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Forward Price | $ / Barrel-bbl		52	[2]	37.29	[3]
Commodity Contracts - Physical [Member] | Weighted Average [Member] | NGL [Member] | Level 3 [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Forward Price | $ / Gallon-gal		0.48	[2]	0.4	[3]
Commodity Option [Member] | Level 3 [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Assets and liabilities accounted for at fair value on a recurring basis		$ (7.0)		$ 94.3
Commodity Option [Member] | Maximum [Member] | Level 3 [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Option Volatility		33.00%	[2]	74.00%	[3]
Commodity Option [Member] | Minimum [Member] | Level 3 [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Option Volatility		22.00%	[2]	13.00%	[3]
Commodity Option [Member] | Weighted Average [Member] | Level 3 [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Option Volatility		25.00%	[2]	36.00%	[3]

[1] As determined by nationally-recognized statistical ratings organizations.

[2] Prices are in dollars per Millions of British Thermal Units, or MMBtu, for natural gas; dollars per Gallon, or Gal, for NGLs; and dollars per barrel, or Bbl, for crude oil.

[3] Prices are in dollars per MMBtu for natural gas, Gal for NGLs and Bbl for crude oil.

[4] Fair values include credit valuation adjustment of approximately $0.3 million.