Pension and Severance Plans (Defined Benefit Plans) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Change in projected benefit obligation:
Projected benefit obligation at January 1	$ 222,509	$ 207,448
Service cost	25,908	29,848	$ 31,355
Interest cost	4,900	4,980	5,244
Benefits paid	(10,466)	(8,380)
Actuarial (gain) loss	(7,169)	6,104
Effects of curtailment	(954)	(2,410)
Settlement (1)	(18,042)	(31,804)
Foreign exchange (gain) loss	(16,499)	16,723
Projected benefit obligation at December 31	200,187	222,509	207,448
Change in plan assets:
Fair value of plan assets at January 1	155,211	145,158
Actual gain (loss) on plan assets	9,463	11,400
Employer contributions	32,354	25,080
Settlement (1)	(18,042)	(31,804)
Benefits paid	(10,466)	(8,380)
Foreign exchange gain (loss)	(11,508)	13,757
Fair value of plan assets at December 31	157,012	155,211	$ 145,158
Funded status of the Plans at December 31	(43,175)	(67,298)
Defined Benefit Plan, Liability
Accumulated benefit obligation	151,700	164,700
Defined Benefit Plan, Pension Plan with Project Benefit Obligation in Excess of Plan Assets [Abstract]
Aggregate projected benefit obligation	128,312	140,424
Aggregate fair value of plan assets	73,159	68,270
Defined Benefit Plan, Plan with Accumulated Benefit Obligation in Excess of Plan Assets [Abstract]
Aggregate accumulated benefit obligation	72,009	76,426
Aggregate fair value of plan assets	$ 24,365	$ 25,292
Defined Benefit Plan, Weighted Average Assumptions Used in Calculating Net Periodic Benefit Cost [Abstract]
Discount rate for determining net periodic pension cost (as a percent)	2.30%	2.50%	3.10%
Discount rate for determining benefit obligations at December 31 (as a percent)	2.60%	2.30%	2.50%
Rate of compensation increase for determining net periodic pension cost (as a percent)	3.70%	3.70%	3.60%
Rate of compensation increase for determining benefit obligations at December 31 (as a percent)	3.70%	3.70%	3.70%
Expected rate of return on plan assets for determining net periodic pension cost (as a percent)	3.70%	3.80%	5.10%