INCOME TAXES (Details 2)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Effective Tax Rate Reconciliation (Percent)
Statutory federal tax rate	35.00%	35.00%	35.00%
State income taxes, net	(1.20%)	8.00%	(38.20%)
Foreign rate differential	(7.70%)	(25.10%)	(129.80%)
U.S. tax on foreign earnings	(70.80%)	24.40%	128.60%
Salt depletion	(16.10%)	45.40%	(38.80%)
Non-deductible transaction costs	0.00%	0.00%	133.10%
Change in valuation allowance	76.00%	(0.70%)	27.90%
Remeasurement of U.S. state deferred taxes	10.20%	9.40%	7.60%
Change in tax contingencies	(7.70%)	(9.70%)	5.00%
U.S. Tax Cuts and Jobs Act	(373.50%)	0.00%	0.00%
Share-based payments	(5.70%)	0.00%	0.00%
Dividends paid to Contributing Employee Ownership Plan	(0.60%)	2.80%	(11.10%)
Return to provision	(0.60%)	5.30%	(4.20%)
U.S. Federal tax credits	(4.20%)	0.60%	(3.10%)
Other, net	(2.00%)	(6.80%)	8.90%
Effective tax rate	(368.90%)	88.60%	120.90%