v3.25.2
Pension plans and other postretirement benefits - Net Periodic Defined Benefit Cost for Defined Benefit Plans (Detail) - USD ($)
$ in Thousands
 3 Months Ended 6 Months Ended
Jun. 30, 2025
Jun. 30, 2024
Jun. 30, 2025
Jun. 30, 2024
Pension Benefits        
Defined Benefit Plan Disclosure [Line Items]        
Service cost $ 2,000 $ 3,000 $ 4,000 $ 5,000
Interest cost on projected benefit obligation 27,000 29,000 54,000 58,000
Expected return on plan assets (47,000) (50,000) (93,000) (101,000)
Amortization of prior service credit 0 0 0 0
Amortization of net actuarial gain 0 (1,000) (1,000) (1,000)
Net periodic benefit $ (18,000) $ (19,000) $ (36,000) $ (39,000)
Defined benefit plan, net periodic benefit cost (credit) excluding service cost, statement of income or comprehensive income [extensible enumeration] Other costs of operations Other costs of operations Other costs of operations Other costs of operations
Other Postretirement Benefits        
Defined Benefit Plan Disclosure [Line Items]        
Service cost $ 1,000 $ 1,000 $ 1,000 $ 1,000
Interest cost on projected benefit obligation 0 0 1,000 1,000
Expected return on plan assets 0 0 0 0
Amortization of prior service credit (1,000) (1,000) (1,000) (1,000)
Amortization of net actuarial gain (1,000) 0 (2,000) (1,000)
Net periodic benefit $ (1,000) $ 0 $ (1,000) $ 0
Defined benefit plan, net periodic benefit cost (credit) excluding service cost, statement of income or comprehensive income [extensible enumeration] Other costs of operations Other costs of operations Other costs of operations Other costs of operations