Supplemental Balance Sheet and Income Statement Information - Accumulated other comprehensive income (loss) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021
Changes in accumulated other comprehensive income (loss)
Beginning balance			$ 590,656
Other comprehensive income (loss), net of tax	$ (658)	$ 2,132	678	$ 2,500
Ending balance	453,200		453,200
Accumulated Other Comprehensive Income (Loss)
Changes in accumulated other comprehensive income (loss)
Beginning balance			(10,634)	(11,124)
Other comprehensive income (loss) before reclassifications			598	2,420
Amounts reclassified from accumulated other comprehensive income (loss)			80	80
Other comprehensive income (loss), net of tax			678	2,500
Ending balance	(9,956)	(8,624)	(9,956)	(8,624)
Gains (losses) on cash flow hedges
Changes in accumulated other comprehensive income (loss)
Beginning balance			2	2
Ending balance	2	2	2	2
Defined benefit pension plan items
Changes in accumulated other comprehensive income (loss)
Beginning balance			(5,356)	(3,616)
Other comprehensive income (loss) before reclassifications			1,428	(1,900)
Amounts reclassified from accumulated other comprehensive income (loss)			80	80
Other comprehensive income (loss), net of tax			1,508	(1,820)
Ending balance	(3,848)	(5,436)	(3,848)	(5,436)
Foreign currency items
Changes in accumulated other comprehensive income (loss)
Beginning balance			(5,280)	(7,510)
Other comprehensive income (loss) before reclassifications			(830)	4,320
Other comprehensive income (loss), net of tax			(830)	4,320
Ending balance	$ (6,110)	$ (3,190)	$ (6,110)	$ (3,190)