Shareholders' equity - Schedule of Reclassification out of Accumulated Other Comprehensive Loss (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Total reclassifications, before tax	$ 5,590	$ (16,342)	$ 6,163
Income tax effect	(1,436)	4,236	(1,590)
Total reclassifications, net of tax	4,154	(12,106)	4,573
Amortization of prior service credit
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Total reclassifications, before tax	(464)	(481)	(481)
Amortization of actuarial loss
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Total reclassifications, before tax	6,054	4,639	5,698
Pension payment timing related charges
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Total reclassifications, before tax	0	300	946
Realized gain on available-for-sale investment
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Total reclassifications, before tax	$ 0	$ (20,800)	$ 0