Income taxes - Components of Comprehensive Provision for Income Taxes Allocation (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Comprehensive provision for income taxes allocable to:
Net income	$ 2,785	$ 7,479	$ (2,515)
Additional paid-in capital			(100)
Other comprehensive income:
Currency translation	(1,800)	(400)	900
Total	7,600	10,300	(2,500)
Defined Benefit Pension Plans
Other comprehensive income:
Defined benefit plans	6,500	$ 3,200	(700)
OPEB
Other comprehensive income:
Defined benefit plans	$ 100		$ (100)