Income taxes - Components of Comprehensive Provision for Income Taxes Allocation (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021
Comprehensive provision for income taxes allocable to:
Net income	$ 6,435	$ 1,901	$ 9,140	$ 4,406
Additional paid-in capital			100
Other comprehensive income:
Currency translation	(2,300)	200	(1,900)	300
Total	4,400	2,400	7,800	5,300
Defined Benefit Pension Plans
Other comprehensive income:
Defined benefit plans	$ 300	$ 300	$ 500	$ 600