Summary of Significant Accounting Policies (Tax Effects of Components of Other Comprehensive Income (Loss) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Accumulated Other Comprehensive Income (Loss) [Line Items]
Total other comprehensive income (loss), Before-Tax Amount	$ 10,644	$ (6,340)	$ 4,717
Total other comprehensive income (loss), Tax (Expense) Benefit	(2,395)	666	(1,471)
TOTAL OTHER COMPREHENSIVE INCOME (LOSS), NET OF TAX	8,249	(5,674)	3,246
Accumulated Other Comprehensive Loss
Accumulated Other Comprehensive Income (Loss) [Line Items]
Total other comprehensive income (loss), Before-Tax Amount	9,645	(4,068)	4,577
Total other comprehensive income (loss), Tax (Expense) Benefit	(2,395)	666	(1,471)
TOTAL OTHER COMPREHENSIVE INCOME (LOSS), NET OF TAX	7,250	(3,402)	3,106
Defined benefit pension plan adjustments
Accumulated Other Comprehensive Income (Loss) [Line Items]
Total other comprehensive income (loss), Before-Tax Amount	4,477	7,230	8,665
Total other comprehensive income (loss), Tax (Expense) Benefit	(1,194)	(2,001)	(2,444)
TOTAL OTHER COMPREHENSIVE INCOME (LOSS), NET OF TAX	3,283	5,229	6,221
Foreign currency translation adjustment
Accumulated Other Comprehensive Income (Loss) [Line Items]
Total other comprehensive income (loss), Before-Tax Amount	961	(3,351)	(508)
Total other comprehensive income (loss), Tax (Expense) Benefit	(126)	556	183
TOTAL OTHER COMPREHENSIVE INCOME (LOSS), NET OF TAX	835	(2,795)	(325)
Unrealized gain (loss) in fair value of investments
Accumulated Other Comprehensive Income (Loss) [Line Items]
Total other comprehensive income (loss), Before-Tax Amount	5,206	(10,219)	(3,440)
Total other comprehensive income (loss), Tax (Expense) Benefit	(1,075)	2,111	790
TOTAL OTHER COMPREHENSIVE INCOME (LOSS), NET OF TAX	4,131	(8,108)	(2,650)
Noncontrolling Interests
Accumulated Other Comprehensive Income (Loss) [Line Items]
Total other comprehensive income (loss), Before-Tax Amount	999	(2,272)	140
Total other comprehensive income (loss), Tax (Expense) Benefit	0	0	0
TOTAL OTHER COMPREHENSIVE INCOME (LOSS), NET OF TAX	$ 999	$ (2,272)	$ 140