COMMITMENTS AND CONTINGENCIES (Narrative) (Details)	1 Months Ended					3 Months Ended		12 Months Ended
	Dec. 31, 2017 USD ($)	Sep. 30, 2017 item	Dec. 31, 2016 USD ($) item	Mar. 31, 2016 mi	May 31, 2007 entity mi	Mar. 31, 2018 USD ($)	Mar. 31, 2017 USD ($)	Dec. 31, 2017 USD ($)
Loss Contingencies [Line Items]
Asset Retirement Obligation	$ 218,117,000		$ 223,872,000			$ 214,709,000	$ 226,012,000	$ 218,117,000
Number of groundwater extraction wells | item		2
Parent Company [Member]
Loss Contingencies [Line Items]
Judge ruled allocation of fault among defendants, percentage	15.00%
Texas Brine [Member]
Loss Contingencies [Line Items]
Number of cases settled | item			1
Cooperating Parties Group [Member]
Loss Contingencies [Line Items]
Number of other companies to perform a Remedial Investigation/ Feasibility Study related to the Lower Passaic River Clean-Up lawsuit | entity					70
Number of miles of the River used in the Remedial Investigation/Feasibility Study | mi					17
Number of miles for bank-to-bank dredging remedy | mi				8
Occidental Chemical Co [Member]
Loss Contingencies [Line Items]
Judge ruled allocation of fault among defendants, percentage	50.00%
Texas Brine [Member]
Loss Contingencies [Line Items]
Judge ruled allocation of fault among defendants, percentage	35.00%
Maximum [Member] | EPA [Member]
Loss Contingencies [Line Items]
Estimated implementation costs						1,380,000,000
Standby Letters of Credit [Member]
Loss Contingencies [Line Items]
Outstanding standby letters of credit						$ 43,239,000
Hewitt Landfill Matter [Member]
Loss Contingencies [Line Items]
Increase in accrual of liability for claims and litigation							$ 1,326,000	$ 15,239,000