Stockholders' equity - Schedule of Changes in Accumulated Other Comprehensive Loss (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2025	Jun. 30, 2024	Jun. 30, 2025	Jun. 30, 2024
Accumulated Other Comprehensive Income Loss [Line Items]
Balance at beginning of period			$ 396,904
Balance at end of period	$ 397,582		397,582
Currency Translation
Accumulated Other Comprehensive Income Loss [Line Items]
Balance at beginning of period	(181,238)	$ (182,085)	(185,423)	$ (177,119)
Other comprehensive income (loss)	3,437	466	7,622	(4,500)
Balance at end of period	(177,801)	(181,619)	(177,801)	(181,619)
Accumulated Defined Benefit Plans Adjustment \| Defined Benefit Pension Plans
Accumulated Other Comprehensive Income Loss [Line Items]
Balance at beginning of period	(36,349)	(40,994)	(36,666)	(41,373)
Other comprehensive income (loss)	323	378	640	757
Balance at end of period	(36,026)	(40,616)	(36,026)	(40,616)
Other \| OPEB plans
Accumulated Other Comprehensive Income Loss [Line Items]
Balance at beginning of period	(1,300)	(1,161)	(1,267)	(1,114)
Other comprehensive income (loss)	(31)	(45)	(64)	(92)
Balance at end of period	(1,331)	(1,206)	(1,331)	(1,206)
Marketable debt securities
Accumulated Other Comprehensive Income Loss [Line Items]
Balance at beginning of period	0	0	0	(15)
Other comprehensive income (loss)	0	7	0	22
Balance at end of period	0	7	0	7
Total accumulated other comprehensive loss
Accumulated Other Comprehensive Income Loss [Line Items]
Balance at beginning of period	(218,887)	(224,240)	(223,356)	(219,621)
Other comprehensive income (loss)	3,729	806	8,198	(3,813)
Balance at end of period	$ (215,158)	$ (223,434)	$ (215,158)	$ (223,434)