Summary of Significant Accounting Policies (Changes in AOCI Balances by Component) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance at the beginning of the period	$ 1,654,921
Balance at the beginning of the period, noncontrolling interests	18,799
Other comprehensive income (loss) before reclassifications	(5,357)	$ 1,330	$ (6,124)
Amounts reclassified from AOCI	1,955	1,776	1,483
Other comprehensive income	(2,272)	140	230
Balance at the end of the period	1,449,718	1,654,921
Balance at the end of the period, noncontrolling interests	(7,734)	18,799
AOCI Attributable to Parent
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance at the beginning of the period	(43,635)	(46,741)	(42,100)
Balance at the end of the period	(47,037)	(43,635)	(46,741)
Defined Benefit Pension Plan
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance at the beginning of the period	(37,866)	(44,087)	(37,826)
Other comprehensive income (loss) before reclassifications	3,370	4,167	(7,993)
Amounts reclassified from AOCI	1,859	2,054	1,732
Balance at the end of the period	(32,637)	(37,866)	(44,087)
Foreign Currency Translation
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance at the beginning of the period	(5,787)	(5,322)	(5,371)
Other comprehensive income (loss) before reclassifications	(1,454)	(465)	49
Amounts reclassified from AOCI	0	0	0
Balance at the end of the period	(7,241)	(5,787)	(5,322)
Unrealized Gain (Loss) in Fair Value of Investments
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance at the beginning of the period	18	2,668	1,097
Other comprehensive income (loss) before reclassifications	(7,273)	(2,372)	1,820
Amounts reclassified from AOCI	96	(278)	(249)
Balance at the end of the period	(7,159)	18	2,668
AOCI Attributable to Noncontrolling Interest
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance at the beginning of the period, noncontrolling interests	542	402	172
Balance at the end of the period, noncontrolling interests	(1,730)	542	402
Defined Benefit Pension Plan
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance at the beginning of the period, noncontrolling interests	0	0	0
Other comprehensive income	0	0	0
Balance at the end of the period, noncontrolling interests	0	0	0
Foreign Currency Translation
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance at the beginning of the period, noncontrolling interests	542	402	172
Other comprehensive income	(1,341)	140	230
Balance at the end of the period, noncontrolling interests	(799)	542	402
Unrealized Loss in Fair Value of Investments
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance at the beginning of the period, noncontrolling interests	0	0	0
Other comprehensive income	(931)	0	0
Balance at the end of the period, noncontrolling interests	$ (931)	$ 0	$ 0