RETIREMENT BENEFITS - Changes in Benefit Obligations and Plan Assets as Well as Funded Status of Retirement Plans (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Change in plan assets
Fair value of plan assets at beginning of year	$ 764,405
Fair value of plan assets at end of year	807,016	$ 764,405
Pension Benefits
Change in benefit obligation
Obligation at beginning of year	674,104	925,129
Service cost	8,573	12,603	$ 14,265
Interest cost	34,725	20,579	17,697
Actuarial losses (gains)	22,938	(231,923)
Special termination benefits	577	0
Plan amendments	(76)	0
Curtailment gain	0	0
Benefits paid	(45,006)	(44,443)
Participants’ contributions	0	0
Foreign currency exchange rate changes	2,891	(7,841)
Obligation at end of year	698,726	674,104	925,129
Change in plan assets
Fair value of plan assets at beginning of year	764,405	1,024,454
Actual return on plan assets	84,849	(218,002)
Employer contributions	2,768	2,396
Participants’ contributions	0	0
Benefits paid	(45,006)	(44,443)
Fair value of plan assets at end of year	807,016	764,405	1,024,454
Funded status	108,290	90,301
Amounts recognized in the consolidated balance sheets
Non-current assets	203,494	169,940
Current liabilities	(3,055)	(2,766)
Non-current liabilities	(92,149)	(76,873)
Net amount recognized	108,290	90,301
Amounts recognized in accumulated other comprehensive loss
Net actuarial loss (gain)	176,877	209,874
Prior service cost (credit)	391	505
Net amount recognized	177,268	210,379
Other Postretirement Benefits
Change in benefit obligation
Obligation at beginning of year	14,447	19,525
Service cost	50	78	107
Interest cost	745	413	363
Actuarial losses (gains)	645	(3,609)
Special termination benefits	0	0
Plan amendments	0	0
Curtailment gain	(1,103)	0
Benefits paid	(1,430)	(1,984)
Participants’ contributions	19	24
Foreign currency exchange rate changes	0	0
Obligation at end of year	13,373	14,447	19,525
Change in plan assets
Fair value of plan assets at beginning of year	0	0
Actual return on plan assets	0	0
Employer contributions	1,411	1,960
Participants’ contributions	19	24
Benefits paid	(1,430)	(1,984)
Fair value of plan assets at end of year	0	0	$ 0
Funded status	(13,373)	(14,447)
Amounts recognized in the consolidated balance sheets
Non-current assets	0	0
Current liabilities	(1,389)	(1,421)
Non-current liabilities	(11,984)	(13,026)
Net amount recognized	(13,373)	(14,447)
Amounts recognized in accumulated other comprehensive loss
Net actuarial loss (gain)	(4,740)	(6,002)
Prior service cost (credit)	(21)	(969)
Net amount recognized	$ (4,761)	$ (6,971)