RETIREMENT AND DEFERRED COMPENSATION PLANS (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
United States
Change in benefit obligation:
Service cost	$ 2,853	$ 2,426	$ 8,546	$ 7,279
Interest cost	1,713	1,752	5,139	5,257
Change in plan assets:
Employer contribution	20,000
Components of net periodic benefit cost:
Service cost	2,853	2,426	8,546	7,279
Interest cost	1,713	1,752	5,139	5,257
Expected return on plan assets	(2,803)	(2,470)	(8,409)	(7,409)
Amortization of net loss	1,214	801	3,642	2,403
Net periodic benefit cost	2,977	2,509	8,918	7,530
Minimum funding requirements			0
Foreign Plans
Change in benefit obligation:
Service cost	1,457	1,447	4,479	4,166
Interest cost	445	459	1,374	1,321
Change in plan assets:
Employer contribution			1,600
Components of net periodic benefit cost:
Service cost	1,457	1,447	4,479	4,166
Interest cost	445	459	1,374	1,321
Expected return on plan assets	(645)	(627)	(1,982)	(1,781)
Amortization of net loss	422	493	1,301	1,400
Amortization of prior service cost	122	104	376	296
Net periodic benefit cost	1,801	$ 1,876	5,548	$ 5,402
Expected contribution in current fiscal year	$ 3,100		$ 3,100