RETIREMENT AND DEFERRED COMPENSATION PLANS - Components of Net Periodic Benefit Cost (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
United States
Components of net periodic benefit cost:
Service cost	$ 4,227	$ 3,577
Interest cost	1,611	1,987
Expected return on plan assets	(3,073)	(3,422)
Amortization of net loss	2,503	1,548
Amortization of prior service cost	0	0
Net periodic benefit cost	5,268	3,690
Foreign Plans
Components of net periodic benefit cost:
Service cost	2,078	1,768
Interest cost	218	340
Expected return on plan assets	(723)	(634)
Amortization of net loss	589	514
Amortization of prior service cost	45	97
Net periodic benefit cost	$ 2,207	$ 2,085