Pension and other postretirement benefits - Amounts recognized in consolidated balance sheet (Detail) - USD ($) $ in Thousands	Dec. 31, 2024	Dec. 31, 2023
Defined Benefit Plan Disclosure [Line Items]
Payroll and benefit-related liabilities	$ (151,263)	$ (146,535)
Pension and postretirement benefit liabilities	(20,185)	(23,989)
Pension
Defined Benefit Plan Disclosure [Line Items]
Other assets	477	27,370
Payroll and benefit-related liabilities	(1,117)	(1,439)
Pension and postretirement benefit liabilities	(13,935)	(15,815)
Accumulated other comprehensive loss (gain)	12,677	164,139
Amounts recognized in balance sheet	(1,898)	174,255
Other Benefits
Defined Benefit Plan Disclosure [Line Items]
Other assets	0	0
Payroll and benefit-related liabilities	(1,025)	(1,361)
Pension and postretirement benefit liabilities	(6,250)	(8,174)
Accumulated other comprehensive loss (gain)	(13,730)	(14,244)
Amounts recognized in balance sheet	$ (21,005)	$ (23,779)