Supplemental Balance Sheet and Income Statement - Accumulated other comprehensive income (loss) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2026	Jun. 30, 2025	Jun. 30, 2026	Jun. 30, 2025
Changes in accumulated other comprehensive income (loss)
Beginning balance			$ 590,727
Other comprehensive income (loss), net of tax	$ (230)	$ (138)	(926)	$ (254)
Ending balance	544,128		544,128
Accumulated Other Comprehensive Income (Loss)
Changes in accumulated other comprehensive income (loss)
Beginning balance			(10,397)	(10,414)
Other comprehensive income (loss) before reclassifications			(953)	(335)
Amounts reclassified from accumulated other comprehensive income (loss)			27	81
Other comprehensive income (loss), net of tax			(926)	(254)
Ending balance	(11,323)	(10,668)	(11,323)	(10,668)
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			(3,282)	(3,444)
Amounts reclassified from accumulated other comprehensive income (loss)			27	81
Other comprehensive income (loss), net of tax			27	81
Ending balance	(3,255)	(3,363)	(3,255)	(3,363)
Foreign currency items
Changes in accumulated other comprehensive income (loss)
Beginning balance			(7,117)	(6,972)
Other comprehensive income (loss) before reclassifications			(953)	(335)
Other comprehensive income (loss), net of tax			(953)	(335)
Ending balance	$ (8,070)	$ (7,307)	$ (8,070)	$ (7,307)