Pension and Severance Plans (Defined Benefit Plans) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Change in projected benefit obligation:
Projected benefit obligation at January 1	$ 159,760	$ 200,187
Service cost	15,032	20,072	$ 25,908
Interest cost	6,202	4,731	4,900
Benefits paid	(14,056)	(8,573)
Actuarial (gain) loss	4,150	(24,571)
Effects of curtailment	(617)	508
Settlement	(1,073)	(16,914)
Foreign exchange (gain) loss	(5,117)	(15,680)
Projected benefit obligation at December 31	164,281	159,760	200,187
Change in plan assets:
Fair value of plan assets at January 1	127,338	157,012
Actual gain (loss) on plan assets	12,325	(6,528)
Employer contributions	7,368	12,946
Settlement	(1,073)	(16,914)
Benefits paid	(14,056)	(8,573)
Foreign exchange gain (loss)	(2,706)	(10,605)
Fair value of plan assets at December 31	129,196	127,338	$ 157,012
Funded status of the Plans at December 31	$ (35,085)	$ (32,422)