v3.26.1
Retirement Benefit Plans - Net Periodic Benefit Cost (Details) - USD ($)
$ in Thousands
 3 Months Ended 6 Months Ended
Jun. 30, 2026
Jun. 30, 2025
Jun. 30, 2026
Jun. 30, 2025
Employees' Pension Plan        
Defined Benefit Plan Disclosure [Line Items]        
Service Cost $ 506 $ 402 $ 953 $ 802
Interest Cost 590 577 1,180 1,161
Expected Return on Plan Assets (1,036) (977) (2,101) (1,986)
Amortization of Prior Service Cost 45 48 91 95
Amortization of Net Gain 0 0 0 0
Net Periodic Cost (Benefit) 105 50 123 72
Plan Contributions During the Period 0 0 0 0
Estimated Future Contributions in the Current Fiscal Year 0   0  
Select Executive Retirement Plan        
Defined Benefit Plan Disclosure [Line Items]        
Service Cost 42 21 67 47
Interest Cost 65 76 130 148
Expected Return on Plan Assets 0 0 0 0
Amortization of Prior Service Cost 10 10 20 20
Amortization of Net Gain 0 0 0 0
Net Periodic Cost (Benefit) 117 107 217 215
Plan Contributions During the Period 117 128 233 248
Estimated Future Contributions in the Current Fiscal Year 233   233  
Postretirement Benefit Plans        
Defined Benefit Plan Disclosure [Line Items]        
Service Cost 5 5 13 16
Interest Cost 57 60 124 139
Expected Return on Plan Assets 0 0 0 0
Amortization of Prior Service Cost 14 25 29 51
Amortization of Net Gain (137) (159) (254) (255)
Net Periodic Cost (Benefit) (61) (69) (88) (49)
Plan Contributions During the Period 78 $ 34 119 $ 91
Estimated Future Contributions in the Current Fiscal Year $ 119   $ 119