DERIVATIVE INSTRUMENTS AND HEDGING ACTIVITIES - Gains and Losses of Derivative Instruments Recognized in Income (Details) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2015	Dec. 31, 2014
Hedge Ineffectiveness
Ineffectiveness excluding the time value component on fair value hedging instruments:
Net loss in income	$ (7,729)	$ (26,859)
Futures Contracts
Derivatives designated as fair value hedging instruments:
Futures contracts for refined products	33,700
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	35,667	50,293
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	(268)	(73)
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	12,489	4,352
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	101	(849)
Derivatives NOT Designated as Hedging Instruments \| Cost of product sales \| Futures contracts for refined petroleum products
Derivatives NOT designated as hedging instruments:
Gains (losses) on derivative instruments recognized in income	(6,559)	(14,151)
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)	2,162	40
Time value excluded from hedge assessment	(9,891)	(26,899)
Derivatives Designated as Hedging Instruments \| Cost of product sales \| Futures contracts for refined petroleum products \| Futures Contracts
Derivatives designated as fair value hedging instruments:
Futures contracts for refined products	75,974	117,283
Derivatives Designated as Hedging Instruments \| Cost of product sales \| Physical inventory - hedged items
Derivatives designated as fair value hedging instruments:
Physical inventory - hedged items	$ (83,703)	$ (144,142)

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.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 4A
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=35706170&loc=SL5618551-113959

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-Publisher FASB
-Name Accounting Standards Codification
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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=35706170&loc=SL5624171-113959

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 25
-Section 50
-Paragraph 1
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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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Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
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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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