Retirement plans - Schedule of Pension Costs (Details) - Retirement Plans - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Defined Benefit Plan Disclosure [Line Items]
Service cost-benefits earned during the period	$ 0	$ 2	$ 7
Interest cost on benefit obligation	16,830	15,887	19,487
Expected return on plan assets	(19,502)	(34,679)	(31,058)
Amortization of prior service cost	90	90	90
Amortization of actuarial loss	4,583	4,952	6,207
Pension payment timing related charge	300	946	0
Expense for (income from) company-sponsored retirement plans	$ 2,301	$ (12,802)	$ (5,267)