EMPLOYEE BENEFIT PLANS - Obligations and Funded Status (Details) - Pension Plans - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Change in benefit obligations:
Benefit obligations at January 1	$ 2,324,080	$ 2,135,143
Service cost	11,915	11,007
Interest cost	67,781	84,960
Actuarial (gain) loss	212,099	274,456
Pension curtailment and settlement	(19,052)	(102,905)
Benefits paid	(104,977)	(96,290)
Foreign currency exchange rate changes	17,247	17,709
Benefit obligations at December 31	2,509,093	2,324,080
Change in plan assets:
Fair value of plan assets at January 1	1,978,708	1,725,543
Actual return on plan assets	275,372	348,354
Employer contribution	136,029	72,202
Benefits paid	(104,977)	(96,290)
Pension settlement	0	(93,049)
Foreign currency exchange rate changes	18,864	21,948
Fair value of plan assets at December 31	2,303,996	1,978,708
Funded status	$ (205,097)	$ (345,372)
Funded percent	92.00%	85.00%