Retirement plans - Schedule of Pension Costs (Details) - Retirement Plans - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Defined Benefit Plan Disclosure [Line Items]
Interest cost on benefit obligation	$ 22,756	$ 24,183	$ 16,830
Expected return on plan assets	(22,066)	(20,940)	(19,502)
Amortization of prior service cost	90	90	90
Amortization of actuarial loss	5,942	6,059	4,583
Pension settlement charge	10,316	0	300
Expense for (income from) company-sponsored retirement plans	$ 17,038	$ 9,392	$ 2,301