FAIR VALUE MEASUREMENTS (Measured on Recurring Basis) (Details) (Fair Value, Measurements, Recurring [Member], USD $) | Jun. 30, 2014 | Dec. 31, 2013 |
In Thousands, unless otherwise specified |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | ' |
Marketable securities | $299,996 | ' |
Non-qualified pension plan assets | 5,047 | 4,905 |
Level 1 [Member] | ' | ' |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | ' |
Marketable securities | 299,996 | ' |
Non-qualified pension plan assets | 5,047 | 4,905 |
Level 2 [Member] | ' | ' |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | ' |
Marketable securities | 0 | ' |
Non-qualified pension plan assets | 0 | 0 |
Level 3 [Member] | ' | ' |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | ' |
Marketable securities | 0 | ' |
Non-qualified pension plan assets | 0 | 0 |
Catalyst lease obligations [Member] | ' | ' |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | ' |
Catalyst lease obligations | 57,429 | 53,089 |
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 |
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 |
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 |
Commodity contract [Member] | ' | ' |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | ' |
Derivative liability, gross carrying value | 13,203 | ' |
Derivative liability, effect of counter-party netting | -12,628 | ' |
Derivative Liability | 575 | 30,354 |
Commodity contract [Member] | Level 1 [Member] | ' | ' |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | ' |
Derivative liability, gross carrying value | 220 | ' |
Derivative Liability | ' | 0 |
Commodity contract [Member] | Level 2 [Member] | ' | ' |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | ' |
Derivative liability, gross carrying value | 12,845 | ' |
Derivative Liability | ' | 6,989 |
Commodity contract [Member] | Level 3 [Member] | ' | ' |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | ' |
Derivative liability, gross carrying value | 138 | ' |
Derivative Liability | ' | 23,365 |
Derivatives included with inventory supply arrangement obligations [Member] | ' | ' |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | ' |
Derivative liability, gross carrying value | 1,247 | ' |
Derivative liability, effect of counter-party netting | 0 | ' |
Derivative Liability | 1,247 | 177 |
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, gross carrying value | 0 | ' |
Derivative Liability | ' | 0 |
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, gross carrying value | 1,247 | ' |
Derivative Liability | ' | 177 |
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, gross carrying value | 0 | ' |
Derivative Liability | ' | 0 |
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 |
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 |
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 |
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 |
Commodity contract [Member] | ' | ' |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | ' |
Derivative assets, gross carrying value | 33,815 | ' |
Derivative assets, effect of counter-party netting | -12,628 | ' |
Derivative assets, net carrying value | 21,187 | 10,933 |
Commodity contract [Member] | Level 1 [Member] | ' | ' |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | ' |
Derivative assets, gross carrying value | 15,017 | ' |
Derivative assets, net carrying value | ' | 4,252 |
Commodity contract [Member] | Level 2 [Member] | ' | ' |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | ' |
Derivative assets, gross carrying value | 15,971 | ' |
Derivative assets, net carrying value | ' | 6,681 |
Commodity contract [Member] | Level 3 [Member] | ' | ' |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | ' |
Derivative assets, gross carrying value | 2,827 | ' |
Derivative assets, net carrying value | ' | 0 |
Derivatives included with intermediation agreement obligations [Member] | ' | ' |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | ' |
Derivative assets, gross carrying value | 15,059 | ' |
Derivative assets, effect of counter-party netting | 0 | ' |
Derivative assets, net carrying value | 15,059 | 6,016 |
Derivatives included with intermediation agreement obligations [Member] | Level 1 [Member] | ' | ' |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | ' |
Derivative assets, gross carrying value | 0 | ' |
Derivative assets, net carrying value | ' | 0 |
Derivatives included with intermediation agreement obligations [Member] | Level 2 [Member] | ' | ' |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | ' |
Derivative assets, gross carrying value | 15,059 | ' |
Derivative assets, net carrying value | ' | 6,016 |
Derivatives included with intermediation agreement obligations [Member] | Level 3 [Member] | ' | ' |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | ' |
Derivative assets, gross carrying value | 0 | ' |
Derivative assets, net carrying value | ' | $0 |