Retirement Benefit Plans (Changes in Benefit Obligations and Plan Assets) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Benefit obligation at beginning of year	$ 517,648	$ 495,746
Service cost	7,707	7,916	$ 11,438
Interest cost	$ 24,047	$ 23,854	$ 14,639
Defined Benefit Plan, Net Periodic Benefit Cost (Credit), Interest Cost, Statement of Income or Comprehensive Income [Extensible Enumeration]	Payroll Taxes Healthcare Costs Pension And Other Postretirement Benefit Expense	Payroll Taxes Healthcare Costs Pension And Other Postretirement Benefit Expense	Payroll Taxes Healthcare Costs Pension And Other Postretirement Benefit Expense
Net actuarial gain (loss)	$ (35,453)	$ 15,285
Benefits paid	(27,718)	(25,153)
Benefit obligation, end of year	486,231	517,648	$ 495,746
Fair value of plan assets at beginning of year	723,064	700,535
Actual return on plan assets	40,388	48,497
Employer contributions	1,264	1,136
Benefit payments	(27,718)	(25,153)
Expenses	(2,178)	(1,951)
Fair value of plan assets, end of year	734,820	723,064	700,535
Funded status at end of year - net asset (liability)	248,589	205,416
Unrecognized loss (gain) at beginning of year	141,049	135,243
Net actuarial loss (gain)	(31,725)	5,806
Unrecognized loss (gain) at end of year	109,324	141,049	135,243
Accumulated benefit obligation	467,634	493,800
Other Post-Retirement Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Benefit obligation at beginning of year	13,404	13,796
Service cost	31	34	59
Interest cost	$ 578	$ 622	$ 375
Defined Benefit Plan, Net Periodic Benefit Cost (Credit), Interest Cost, Statement of Income or Comprehensive Income [Extensible Enumeration]	Payroll Taxes Healthcare Costs Pension And Other Postretirement Benefit Expense	Payroll Taxes Healthcare Costs Pension And Other Postretirement Benefit Expense	Payroll Taxes Healthcare Costs Pension And Other Postretirement Benefit Expense
Plan participants' contributions	$ 608	$ 691
Net actuarial gain (loss)	(2,371)	92
Benefits paid	(1,803)	(1,831)
Benefit obligation, end of year	10,447	13,404	$ 13,796
Employer contributions	1,196	1,140
Plan participants' contributions	608	691
Benefit payments	(1,804)	(1,831)
Funded status at end of year - net asset (liability)	(10,447)	(13,404)
Unrecognized loss (gain) at beginning of year	(7,902)	(8,837)
Net actuarial loss (gain)	(1,572)	935
Unrecognized loss (gain) at end of year	$ (9,474)	$ (7,902)	$ (8,837)