BENEFIT PLANS (Narrative) (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019 USD ($) employee ShareBasedCompensationPlan item	Dec. 31, 2018 USD ($) item	Dec. 31, 2017 USD ($)
Defined Benefit Plan Disclosure [Line Items]
Number of defined contribution plans | ShareBasedCompensationPlan		2
Expected return on plan assets		5.75%	7.00%
Contributions to multiemployer pension plans		$ 10,385	$ 10,081	$ 9,253
Percentage of contributions to individual multiemployer pension funds		5.00%	5.00%	5.00%
Percentage of domestic hourly labor force covered by collective bargaining agreements		7.40%
Percentage of domestic hourly labor force covered by collective bargaining agreements expiring in 2017		11.40%
Number of unfunded supplemental retirement plans | item		1	1
Accrued costs for supplemental retirement plan		$ 1,069	$ 1,122
Amount plan assets of Chemical Plan exceeds accumulated benefit obligation		9,056	6,525
Expense recognized related to defined contribution plans		$ 53,853	40,718	$ 44,562
Mexico [Member]
Defined Benefit Plan Disclosure [Line Items]
Number of employees | employee		330
Forecast [Member]
Defined Benefit Plan Disclosure [Line Items]
Expected return on plan assets	5.75%
Pension Plans, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Number of funded, noncontributory defined benefit pension plans | ShareBasedCompensationPlan		3
Normal retirement age		65 years
Projected benefit obligation		$ 1,090,893	958,936	$ 1,091,223
Accumulated benefit obligation		1,090,239	$ 958,899
Estimated net actuarial loss expected to be amortized from accumulated other comprehensive income		12,905
Estimated prior service cost that will be amortized from accumulated other comprehensive income		$ 1,339
Expected return on plan assets		5.75%	7.00%	7.00%
Employer contributions		$ 8,882	$ 109,631	$ 20,023
Estimated employer contribution in 2019		$ 8,579
Discount rate		3.28%	4.39%	3.72%
Estimated weighted-average discount rate to measure service cost		4.59%	3.90%
Estimated weighted-average discount rate to measure interest cost		4.02%	3.35%
Number of unions | item		2
Pension Plans, Defined Benefit [Member] | Qualified Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Discretionary qualified plan contribution			$ 100,000	$ 10,600
Employer contributions		$ 0
Pension Plans, Defined Benefit [Member] | Nonqualified Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Number of unfunded, nonqualified pension plans | ShareBasedCompensationPlan		3
Projected benefit obligation		$ 70,298	71,435
Accumulated benefit obligation		70,298	71,435
Employer contributions		8,882	$ 9,631	9,423
Estimated employer contribution in 2019		$ 8,579
Pension Plans, Defined Benefit [Member] | Return Seeking [Member]
Defined Benefit Plan Disclosure [Line Items]
Target allocation ranges for plan assets		50.00%	70.00%
Pension Plans, Defined Benefit [Member] | Liability Hedge [Member]
Defined Benefit Plan Disclosure [Line Items]
Target allocation ranges for plan assets		50.00%	30.00%
Other Postretirement Benefit Plans, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Normal retirement age		65 years
Projected benefit obligation		$ 41,187	$ 40,834	$ 43,480
Estimated net actuarial loss expected to be amortized from accumulated other comprehensive income		(956)
Estimated prior service cost that will be amortized from accumulated other comprehensive income		(3,919)
Estimated employer contribution in 2019		$ 5,340
Discount rate		2.84%	4.01%	3.33%
Estimated weighted-average discount rate to measure service cost		4.23%	3.56%
Estimated weighted-average discount rate to measure interest cost		3.63%	2.90%
Minimum [Member]
Defined Benefit Plan Disclosure [Line Items]
Discount rate		2.67%	3.92%
Maximum [Member]
Defined Benefit Plan Disclosure [Line Items]
Discount rate		3.37%	4.47%