DERIVATIVE INSTRUMENTS AND HEDGING ACTIVITIES - Gains and Losses on Derivative Instruments (Details) - USD ($) $ in Thousands	3 Months Ended
Mar. 31, 2016	Mar. 31, 2015
Hedge Ineffectiveness
Ineffectiveness excluding the time value component on fair value hedging instruments:
Net gain (loss) in income	$ 9,939	$ (8,423)
Futures contracts for refined products
Derivatives designated as fair value hedging instruments:
Futures contracts for refined products	(2,900)
Derivatives NOT Designated as Hedging Instruments \| Product sales \| Physical fixed price derivative contracts
Derivatives NOT designated as hedging instruments:
Gains (losses) on derivative instruments recognized in income	(2,255)	7,055
Derivatives NOT Designated as Hedging Instruments \| Product sales \| Physical index derivative contracts
Derivatives NOT designated as hedging instruments:
Gains (losses) on derivative instruments recognized in income	(27)	(5)
Derivatives NOT Designated as Hedging Instruments \| Cost of product sales \| Physical fixed price derivative contracts
Derivatives NOT designated as hedging instruments:
Gains (losses) on derivative instruments recognized in income	5,115	2,639
Derivatives NOT Designated as Hedging Instruments \| Cost of product sales \| Physical index derivative contracts
Derivatives NOT designated as hedging instruments:
Gains (losses) on derivative instruments recognized in income	214	(156)
Derivatives NOT Designated as Hedging Instruments \| Cost of product sales \| Futures contracts for refined products
Derivatives NOT designated as hedging instruments:
Gains (losses) on derivative instruments recognized in income	(1,482)	8,705
Derivatives Designated as Hedging Instruments \| Cost of product sales \| Hedge Ineffectiveness
Ineffectiveness excluding the time value component on fair value hedging instruments:
Fair value hedge ineffectiveness (excluding time value)	647	1,066
Time value excluded from hedge assessment	9,292	(9,489)
Derivatives Designated as Hedging Instruments \| Cost of product sales \| Futures contracts for refined products
Derivatives designated as fair value hedging instruments:
Futures contracts for refined products	1,613	(17,847)
Derivatives Designated as Hedging Instruments \| Cost of product sales \| Physical inventory - hedged items
Derivatives designated as fair value hedging instruments:
Physical inventory - hedged items	$ 8,326	$ 9,424

Amount of gain (loss) from the increase (decrease) in fair value of derivative and nonderivative instruments designated as fair value hedging instruments recognized in the income statement.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 25
-Section 50
-Paragraph 1
-Subparagraph (a)(1)
-URI http://asc.fasb.org/extlink&oid=6886632&loc=d3e76258-113986

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Amount of the increase (decrease) in fair value of the hedged item in a fair value hedge recognized in the income statement.

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Amount of increase (decrease) in the fair value of derivatives recognized in the income statement.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 4A
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The portion of gains and losses (net) on derivative instruments designated and qualifying as hedging instruments representing (a) the amount of the hedge ineffectiveness and (b) the amount, if any, excluded from the assessment of hedge effectiveness.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 4C
-Subparagraph (d)
-URI http://asc.fasb.org/extlink&oid=64837297&loc=SL5624171-113959

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-Publisher FASB
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-URI http://asc.fasb.org/extlink&oid=6886632&loc=d3e76258-113986

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Net gain (loss) relating to components of the gain (loss) on the fair value hedging instrument excluded from the assessment of fair value hedge effectiveness. Recognized in earnings.

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Amount of gain (loss)recognized in the income statement from the hedging ineffectiveness of a fair value hedge.

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