RETIREMENT AND DEFERRED COMPENSATION PLANS (Tables)

9 Months Ended

Sep. 30, 2020

Retirement Benefits [Abstract]

Components of net periodic benefit cost

Components of Net Periodic Benefit Cost:

​	Domestic Plans				Foreign Plans
Three Months Ended September 30,	2020		2019		2020		2019
Service cost	$	3,570	$	2,772	$	1,867	$	1,429
Interest cost	1,761		1,845		360		491
Expected return on plan assets	(3,062)		(3,095)		(671)		(581)
Amortization of net loss	1,422		490		544		356
Amortization of prior service cost	—		—		101		111
Net periodic benefit cost	$	3,691	$	2,012	$	2,201	$	1,806

​	Domestic Plans				Foreign Plans
Nine Months Ended September 30,	2020		2019		2020		2019
Service cost	$	10,709	$	8,320	$	5,402	$	4,334
Interest cost	5,284		5,536		1,040		1,487
Expected return on plan assets	(9,186)		(9,284)		(1,936)		(1,759)
Amortization of net loss	4,264		1,468		1,572		1,078
Amortization of prior service cost	—		—		293		337
Net periodic benefit cost	$	11,071	$	6,040	$	6,371	$	5,477