Supplemental Balance Sheet and Income Statement Information - Accumulated other comprehensive income (loss) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Changes in accumulated other comprehensive income (loss)
Beginning balance	$ 368,956
Other comprehensive income (loss), net of tax	206	$ (404)	$ 490
Ending balance	326,614	368,956
Accumulated Other Comprehensive Income
Changes in accumulated other comprehensive income (loss)
Beginning balance	(11,038)	(10,634)
Other comprehensive income (loss) before reclassifications	45	(564)
Amounts reclassified from accumulated other comprehensive income (loss)	161	160
Other comprehensive income (loss), net of tax	206	(404)
Ending balance	(10,832)	(11,038)	(10,634)
Gains (losses) on cash flow hedges
Changes in accumulated other comprehensive income (loss)
Beginning balance	2	2
Ending balance	2	2	2
Defined benefit pension plan items
Changes in accumulated other comprehensive income (loss)
Beginning balance	(3,767)	(5,356)
Other comprehensive income (loss) before reclassifications		1,429
Amounts reclassified from accumulated other comprehensive income (loss)	161	160
Other comprehensive income (loss), net of tax	161	1,589
Ending balance	(3,606)	(3,767)	(5,356)
Foreign currency items
Changes in accumulated other comprehensive income (loss)
Beginning balance	(7,273)	(5,280)
Other comprehensive income (loss) before reclassifications	45	(1,993)
Other comprehensive income (loss), net of tax	45	(1,993)
Ending balance	$ (7,228)	$ (7,273)	$ (5,280)