INCOME TAXES (Components of Deferred Tax Assets and Liabilities) (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Deferred tax assets
Purchase interest step-up	$ 325,405	$ 639,340
Inventory	0	90,133
Pension, employee benefits and compensation	40,455	42,573
Hedging	24,175	8,696
Net operating loss carry forwards	137,887	128,283
Environmental liabilities	38,388	73,031
Other	3,709	5,859
Total deferred tax assets	570,019	987,915
Valuation allowances	0	0
Total deferred tax assets, net	570,019	987,915
Deferred tax liabilities
Property, plant and equipment	528,336	628,373
Inventory	21,200	22,269
Other	0	3,666
Total deferred tax liabilities	549,536	654,308
Net deferred tax assets	$ 20,483	$ 333,607