Employee benefits - Breakdown of pension and OPEB plans assets and liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2024	Dec. 31, 2023
Defined Benefit Plan Disclosure [Line Items]
Non-current assets	$ 33,233	$ 23,404
Pension Plans
Defined Benefit Plan Disclosure [Line Items]
Non-current assets	33,233	23,404
Current liabilities	222	222
Non-current liabilities	5,594	6,550
OPEB Plan
Defined Benefit Plan Disclosure [Line Items]
Non-current assets	0	0
Current liabilities	5,304	5,595
Non-current liabilities	$ 93,868	$ 111,451