Supplemental Balance Sheet and Income Statement Information - Accumulated Other Comp Inc (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Changes in accumulated other comprehensive income (loss)
Balance at the beginning of the period			$ 1,151,384
Other comprehensive income (loss), net of tax	$ (2,248)	$ 3,558	252	$ (6,842)
Balance at the end of the period	709,021		709,021
Accumulated Other Comprehensive Income
Changes in accumulated other comprehensive income (loss)
Balance at the beginning of the period			(11,124)	(11,788)
Other comprehensive income (loss) before reclassifications			132	(7,029)
Amounts reclassified from accumulated other comprehensive income (loss)			120	187
Other comprehensive income (loss), net of tax			252	(6,842)
Balance at the end of the period	(10,872)	(18,630)	(10,872)	(18,630)
Gains (losses) on cash flow hedges
Changes in accumulated other comprehensive income (loss)
Balance at the beginning of the period			2	(65)
Amounts reclassified from accumulated other comprehensive income (loss)				67
Other comprehensive income (loss), net of tax				67
Balance at the end of the period	2	2	2	2
Defined benefit pension plan items
Changes in accumulated other comprehensive income (loss)
Balance at the beginning of the period			(3,616)	(3,778)
Other comprehensive income (loss) before reclassifications			(1,900)
Amounts reclassified from accumulated other comprehensive income (loss)			120	120
Other comprehensive income (loss), net of tax			(1,780)	120
Balance at the end of the period	(5,396)	(3,658)	(5,396)	(3,658)
Foreign currency items
Changes in accumulated other comprehensive income (loss)
Balance at the beginning of the period			(7,510)	(7,945)
Other comprehensive income (loss) before reclassifications			2,032	(7,029)
Other comprehensive income (loss), net of tax			2,032	(7,029)
Balance at the end of the period	$ (5,478)	$ (14,974)	$ (5,478)	$ (14,974)