RETIREMENT AND DEFERRED COMPENSATION PLANS - Components of Net Periodic Benefit Cost (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
United States
Components of net periodic benefit cost:
Service cost	$ 4,074	$ 3,570	$ 12,242	$ 10,709
Interest cost	1,601	1,761	4,816	5,284
Expected return on plan assets	(3,060)	(3,062)	(9,197)	(9,186)
Amortization of net loss	2,498	1,422	7,502	4,264
Amortization of prior service cost	0	0	0	0
Net periodic benefit cost	5,113	3,691	15,363	11,071
Foreign Plans
Components of net periodic benefit cost:
Service cost	2,037	1,867	6,186	5,402
Interest cost	203	360	629	1,040
Expected return on plan assets	(675)	(671)	(2,119)	(1,936)
Amortization of net loss	568	544	1,748	1,572
Amortization of prior service cost	34	101	123	293
Net periodic benefit cost	$ 2,167	$ 2,201	$ 6,567	$ 6,371