Income taxes - Components of Comprehensive Provision (Benefit) for Income Taxes Allocation (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
Comprehensive provision (benefit) for income taxes allocable to:
Income tax expense (benefit)	$ (16,053)	$ 14,057	$ (7,001)
Other comprehensive income (loss):
Currency translation	2,103	(2,207)	241
Other	(27)	28	35
Total	(3,901)	13,073	(7,086)
Pension Plan
Other comprehensive income (loss):
Pension plans	$ 10,022	$ 1,251	$ (291)