OTHER LONG-TERM LIABILITIES (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Other Long-Term Liabilities [Abstract]
Defined benefit pension plan liabilities	$ 74,972	$ 63,579
Post-retirement medical plan liabilities	19,345	21,527
Environmental liabilities	135,145	138,545
Railcar Liability	23,315	0
Other	824	310
Other long-term liabilities	$ 253,601	$ 223,961