Retirement Benefit Plans - Net Periodic Benefit Cost (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2026	Mar. 31, 2025
Employees' Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Service Cost	$ 447	$ 400
Interest Cost	590	584
Expected Return on Plan Assets	(1,065)	(1,009)
Amortization of Prior Service Cost	46	47
Amortization of Net (Gain)	0	0
Net Periodic Benefit Cost (Benefit)	18	22
Plan Contributions During the Period	0	0
Estimated Future Contributions in the Current Fiscal Year	0
Select Executive Retirement Plan
Defined Benefit Plan Disclosure [Line Items]
Service Cost	25	26
Interest Cost	65	72
Expected Return on Plan Assets	0	0
Amortization of Prior Service Cost	10	10
Amortization of Net (Gain)	0	0
Net Periodic Benefit Cost (Benefit)	100	108
Plan Contributions During the Period	116	120
Estimated Future Contributions in the Current Fiscal Year	349
Postretirement Benefit Plans
Defined Benefit Plan Disclosure [Line Items]
Service Cost	8	11
Interest Cost	67	79
Expected Return on Plan Assets	0	0
Amortization of Prior Service Cost	15	26
Amortization of Net (Gain)	(117)	(96)
Net Periodic Benefit Cost (Benefit)	(27)	20
Plan Contributions During the Period	41	$ 57
Estimated Future Contributions in the Current Fiscal Year	$ 123