Supplemental Balance Sheet and Income Statement Information - Accumulated Other Comp Inc (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 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	368	$ (17,218)
Balance at the end of the period	1,013,753
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	328	(17,365)
Amounts reclassified from accumulated other comprehensive income (loss)	40	147
Other comprehensive income (loss), net of tax	368	(17,218)
Balance at the end of the period	(10,756)	(29,006)
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)		107
Other comprehensive income (loss), net of tax		107
Balance at the end of the period	2	42
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)	40	40
Other comprehensive income (loss), net of tax	(1,860)	40
Balance at the end of the period	(5,476)	(3,738)
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	2,228	(17,365)
Other comprehensive income (loss), net of tax	2,228	(17,365)
Balance at the end of the period	$ (5,282)	$ (25,310)