FAIR VALUE MEASUREMENTS (Measured on Recurring Basis) (Details) (USD $) | Jun. 30, 2014 | Mar. 31, 2014 | Dec. 31, 2013 | Jun. 30, 2013 | Mar. 31, 2013 | Dec. 31, 2012 |
In Thousands, unless otherwise specified |
Commodity contract [Member] | ' | ' | ' | ' | ' | ' |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | ' | ' | ' | ' | ' |
Fair Value, Measurement with Unobservable Inputs Reconciliations, Recurring Basis, Liability Value | $2,689 | ($3,751) | ($23,365) | $0 | $21,358 | $21,358 |
Fair Value, Measurements, Recurring [Member] | ' | ' | ' | ' | ' | ' |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | ' | ' | ' | ' | ' |
Defined Benefit Plan, Fair Value of Plan Assets | 5,047 | ' | 4,905 | ' | ' | ' |
Fair Value, Measurements, Recurring [Member] | Level 1 [Member] | ' | ' | ' | ' | ' | ' |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | ' | ' | ' | ' | ' |
Defined Benefit Plan, Fair Value of Plan Assets | 5,047 | ' | 4,905 | ' | ' | ' |
Fair Value, Measurements, Recurring [Member] | Level 2 [Member] | ' | ' | ' | ' | ' | ' |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | ' | ' | ' | ' | ' |
Defined Benefit Plan, Fair Value of Plan Assets | 0 | ' | 0 | ' | ' | ' |
Fair Value, Measurements, Recurring [Member] | Level 3 [Member] | ' | ' | ' | ' | ' | ' |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | ' | ' | ' | ' | ' |
Defined Benefit Plan, Fair Value of Plan Assets | 0 | ' | 0 | ' | ' | ' |
Fair Value, Measurements, Recurring [Member] | Catalyst lease obligations [Member] | ' | ' | ' | ' | ' | ' |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | ' | ' | ' | ' | ' |
Catalyst lease obligations | 57,429 | ' | 53,089 | ' | ' | ' |
Fair Value, Measurements, Recurring [Member] | Catalyst lease obligations [Member] | Level 1 [Member] | ' | ' | ' | ' | ' | ' |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | ' | ' | ' | ' | ' |
Catalyst lease obligations | 0 | ' | 0 | ' | ' | ' |
Fair Value, Measurements, Recurring [Member] | Catalyst lease obligations [Member] | Level 2 [Member] | ' | ' | ' | ' | ' | ' |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | ' | ' | ' | ' | ' |
Catalyst lease obligations | 57,429 | ' | 53,089 | ' | ' | ' |
Fair Value, Measurements, Recurring [Member] | Catalyst lease obligations [Member] | Level 3 [Member] | ' | ' | ' | ' | ' | ' |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | ' | ' | ' | ' | ' |
Catalyst lease obligations | 0 | ' | 0 | ' | ' | ' |
Fair Value, Measurements, Recurring [Member] | Commodity contract [Member] | ' | ' | ' | ' | ' | ' |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | ' | ' | ' | ' | ' |
Derivative Liability, Fair Value, Amount Not Offset Against Collateral | 13,203 | ' | ' | ' | ' | ' |
Derivative, Collateral, Right to Reclaim Cash | -12,628 | ' | ' | ' | ' | ' |
Derivative Liability | 575 | ' | 30,354 | ' | ' | ' |
Fair Value, Measurements, Recurring [Member] | Commodity contract [Member] | Level 1 [Member] | ' | ' | ' | ' | ' | ' |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | ' | ' | ' | ' | ' |
Derivative Liability, Fair Value, Amount Not Offset Against Collateral | 220 | ' | ' | ' | ' | ' |
Derivative Liability | ' | ' | 0 | ' | ' | ' |
Fair Value, Measurements, Recurring [Member] | Commodity contract [Member] | Level 2 [Member] | ' | ' | ' | ' | ' | ' |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | ' | ' | ' | ' | ' |
Derivative Liability, Fair Value, Amount Not Offset Against Collateral | 12,845 | ' | ' | ' | ' | ' |
Derivative Liability | ' | ' | 6,989 | ' | ' | ' |
Fair Value, Measurements, Recurring [Member] | Commodity contract [Member] | Level 3 [Member] | ' | ' | ' | ' | ' | ' |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | ' | ' | ' | ' | ' |
Derivative Liability, Fair Value, Amount Not Offset Against Collateral | 138 | ' | ' | ' | ' | ' |
Derivative Liability | ' | ' | 23,365 | ' | ' | ' |
Fair Value, Measurements, Recurring [Member] | Derivatives included with inventory supply arrangement obligations [Member] | ' | ' | ' | ' | ' | ' |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | ' | ' | ' | ' | ' |
Derivative Liability, Fair Value, Amount Not Offset Against Collateral | 1,247 | ' | ' | ' | ' | ' |
Derivative, Collateral, Right to Reclaim Cash | 0 | ' | ' | ' | ' | ' |
Derivative Liability | 1,247 | ' | 177 | ' | ' | ' |
Fair Value, Measurements, Recurring [Member] | Derivatives included with inventory supply arrangement obligations [Member] | Level 1 [Member] | ' | ' | ' | ' | ' | ' |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | ' | ' | ' | ' | ' |
Derivative Liability, Fair Value, Amount Not Offset Against Collateral | 0 | ' | ' | ' | ' | ' |
Derivative Liability | ' | ' | 0 | ' | ' | ' |
Fair Value, Measurements, Recurring [Member] | Derivatives included with inventory supply arrangement obligations [Member] | Level 2 [Member] | ' | ' | ' | ' | ' | ' |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | ' | ' | ' | ' | ' |
Derivative Liability, Fair Value, Amount Not Offset Against Collateral | 1,247 | ' | ' | ' | ' | ' |
Derivative Liability | ' | ' | 177 | ' | ' | ' |
Fair Value, Measurements, Recurring [Member] | Derivatives included with inventory supply arrangement obligations [Member] | Level 3 [Member] | ' | ' | ' | ' | ' | ' |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | ' | ' | ' | ' | ' |
Derivative Liability, Fair Value, Amount Not Offset Against Collateral | 0 | ' | ' | ' | ' | ' |
Derivative Liability | ' | ' | 0 | ' | ' | ' |
Fair Value, Measurements, Recurring [Member] | Money market funds [Member] | ' | ' | ' | ' | ' | ' |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | ' | ' | ' | ' | ' |
Cash and cash equivalents | 5,546 | ' | 5,857 | ' | ' | ' |
Fair Value, Measurements, Recurring [Member] | Money market funds [Member] | Level 1 [Member] | ' | ' | ' | ' | ' | ' |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | ' | ' | ' | ' | ' |
Cash and cash equivalents | 5,546 | ' | 5,857 | ' | ' | ' |
Fair Value, Measurements, Recurring [Member] | Money market funds [Member] | Level 2 [Member] | ' | ' | ' | ' | ' | ' |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | ' | ' | ' | ' | ' |
Cash and cash equivalents | 0 | ' | 0 | ' | ' | ' |
Fair Value, Measurements, Recurring [Member] | Money market funds [Member] | Level 3 [Member] | ' | ' | ' | ' | ' | ' |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | ' | ' | ' | ' | ' |
Cash and cash equivalents | 0 | ' | 0 | ' | ' | ' |
Fair Value, Measurements, Recurring [Member] | Commodity contract [Member] | ' | ' | ' | ' | ' | ' |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | ' | ' | ' | ' | ' |
Derivative Asset, Fair Value, Amount Not Offset Against Collateral | 33,815 | ' | ' | ' | ' | ' |
Derivative assets, Effect of Counter-party Netting | -12,628 | ' | ' | ' | ' | ' |
Derivative assets, Net Carrying Value on Balance Sheet | 21,187 | ' | 10,933 | ' | ' | ' |
Fair Value, Measurements, Recurring [Member] | Commodity contract [Member] | Level 1 [Member] | ' | ' | ' | ' | ' | ' |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | ' | ' | ' | ' | ' |
Derivative Asset, Fair Value, Amount Not Offset Against Collateral | 15,017 | ' | ' | ' | ' | ' |
Derivative assets, Net Carrying Value on Balance Sheet | ' | ' | 4,252 | ' | ' | ' |
Fair Value, Measurements, Recurring [Member] | Commodity contract [Member] | Level 2 [Member] | ' | ' | ' | ' | ' | ' |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | ' | ' | ' | ' | ' |
Derivative Asset, Fair Value, Amount Not Offset Against Collateral | 15,971 | ' | ' | ' | ' | ' |
Derivative assets, Net Carrying Value on Balance Sheet | ' | ' | 6,681 | ' | ' | ' |
Fair Value, Measurements, Recurring [Member] | Commodity contract [Member] | Level 3 [Member] | ' | ' | ' | ' | ' | ' |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | ' | ' | ' | ' | ' |
Derivative Asset, Fair Value, Amount Not Offset Against Collateral | 2,827 | ' | ' | ' | ' | ' |
Derivative assets, Net Carrying Value on Balance Sheet | ' | ' | 0 | ' | ' | ' |
Fair Value, Measurements, Recurring [Member] | Derivatives included with intermediation agreement obligations [Member] | ' | ' | ' | ' | ' | ' |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | ' | ' | ' | ' | ' |
Derivative Asset, Fair Value, Amount Not Offset Against Collateral | 15,059 | ' | ' | ' | ' | ' |
Derivative assets, Effect of Counter-party Netting | 0 | ' | ' | ' | ' | ' |
Derivative assets, Net Carrying Value on Balance Sheet | 15,059 | ' | 6,016 | ' | ' | ' |
Fair Value, Measurements, Recurring [Member] | Derivatives included with intermediation agreement obligations [Member] | Level 1 [Member] | ' | ' | ' | ' | ' | ' |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | ' | ' | ' | ' | ' |
Derivative Asset, Fair Value, Amount Not Offset Against Collateral | 0 | ' | ' | ' | ' | ' |
Derivative assets, Net Carrying Value on Balance Sheet | ' | ' | 0 | ' | ' | ' |
Fair Value, Measurements, Recurring [Member] | Derivatives included with intermediation agreement obligations [Member] | Level 2 [Member] | ' | ' | ' | ' | ' | ' |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | ' | ' | ' | ' | ' |
Derivative Asset, Fair Value, Amount Not Offset Against Collateral | 15,059 | ' | ' | ' | ' | ' |
Derivative assets, Net Carrying Value on Balance Sheet | ' | ' | 6,016 | ' | ' | ' |
Fair Value, Measurements, Recurring [Member] | Derivatives included with intermediation agreement obligations [Member] | Level 3 [Member] | ' | ' | ' | ' | ' | ' |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | ' | ' | ' | ' | ' |
Derivative Asset, Fair Value, Amount Not Offset Against Collateral | 0 | ' | ' | ' | ' | ' |
Derivative assets, Net Carrying Value on Balance Sheet | ' | ' | $0 | ' | ' | ' |