INCOME TAXES (Details 2)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Effective Tax Rate Reconciliation (Percent)
Statutory federal tax rate	21.00%	21.00%	21.00%
State income taxes, net	1.10%	(5.40%)	2.00%
Foreign rate differential	(0.20%)	19.40%	1.80%
U.S. tax on foreign earnings	(1.80%)	0.00%	1.10%
Salt depletion	1.00%	29.00%	(2.40%)
Change in valuation allowance	(3.50%)	(64.90%)	3.80%
Remeasurement of U.S. state deferred taxes	(0.10%)	16.10%	(0.60%)
Change in tax contingencies	0.20%	35.40%	(0.70%)
U.S. Tax Cuts and Jobs Act	0.00%	0.00%	(0.80%)
Share-based payments	0.00%	0.70%	0.00%
Dividends paid to Contributing Employee Ownership Plan	0.00%	1.10%	(0.10%)
Return to provision	0.30%	15.00%	(0.10%)
U.S. federal tax credits	0.20%	6.40%	(0.40%)
Goodwill impairment charge	(13.30%)	0.00%	0.00%
Other, net	0.00%	(4.40%)	0.40%
Effective tax rate	4.90%	69.40%	25.00%