v3.26.1
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, 2026
Jun. 30, 2025
Jun. 30, 2026
Jun. 30, 2025
Pension Benefits        
Defined Benefit Plan Disclosure [Line Items]        
Service cost $ 2,000 $ 2,000 $ 4,000 $ 4,000
Interest cost on benefit obligation 23,000 27,000 46,000 54,000
Expected return on plan assets (42,000) (47,000) (85,000) (93,000)
Amortization of prior service credit and actuarial gains (1,000) 0 (1,000) (1,000)
Net periodic benefit $ (18,000) $ (18,000) (36,000) (36,000)
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 Postretirement Benefits        
Defined Benefit Plan Disclosure [Line Items]        
Service cost $ 1,000 $ 1,000 1,000 1,000
Interest cost on benefit obligation 0 0 1,000 1,000
Expected return on plan assets 0 0 0 0
Amortization of prior service credit and actuarial gains (1,000) (2,000) (2,000) (3,000)
Net periodic benefit $ 0 $ (1,000) $ 0 $ (1,000)
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