Pension and Severance Plans (Impact on Accumulated Other Comprehensive Income) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Balance at beginning of period	$ 3,699,701	$ 2,972,546	$ 2,353,959
Amortization and settlement gain included in net periodic pension cost	(526)	(1,003)
Net gain (loss) arising during period	177	(2,276)
Total other comprehensive income (loss)	(349)	(3,279)	(7,292)
Balance at end of period	3,995,035	3,699,701	2,972,546
Prior Service Cost
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Balance at beginning of period	602	602
Amortization and settlement gain included in net periodic pension cost	0	0
Net gain (loss) arising during period	0	0
Total other comprehensive income (loss)	0	0
Balance at end of period	602	602	602
Actuarial Net Gain (Loss)
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Balance at beginning of period	13,618	5,014
Amortization and settlement gain included in net periodic pension cost	(46)	(1,021)
Net gain (loss) arising during period	1,731	9,625
Total other comprehensive income (loss)	1,685	8,604
Balance at end of period	15,303	13,618	5,014
Total
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Balance at beginning of period	14,220	5,616
Amortization and settlement gain included in net periodic pension cost	(46)	(1,021)
Net gain (loss) arising during period	1,731	9,625
Total other comprehensive income (loss)	1,685	8,604
Balance at end of period	$ 15,905	$ 14,220	$ 5,616