Pension plan and 401(k) Program - Change in Benefit Obligations (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Change in benefit obligation:
Benefit obligation, beginning of year	$ 30,772	$ 30,185
Service cost	2,535	2,166	$ 1,982
Interest cost	244	197	253
Actuarial losses (gains)	2,904	771
Benefits paid	(707)	(2,446)
Translation adjustments and other	658	(101)
Benefit obligation, end of year	$ 36,406	$ 30,772	$ 30,185