Accumulated Other Comprehensive Income (Loss) - Roll Forward (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Rollforward of Accumulated other comprehensive income (loss)
Beginning balance	$ 1,081,796	$ 947,994
Other comprehensive income (loss) before reclassifications, net of tax	3,519	2,812
Amounts reclassified from accumulated other comprehensive income (loss), net of tax	(2,188)	(551)
Net current-period other comprehensive income (loss)	1,331	2,261
Ending balance	924,366	975,060
Foreign Currency Derivatives
Rollforward of Accumulated other comprehensive income (loss)
Beginning balance	3,341	3,317
Other comprehensive income (loss) before reclassifications, net of tax	3,279	2,341
Amounts reclassified from accumulated other comprehensive income (loss), net of tax	(2,935)	(1,196)
Net current-period other comprehensive income (loss)	344	1,145
Ending balance	3,685	4,462
Defined Benefit Plan Items
Rollforward of Accumulated other comprehensive income (loss)
Beginning balance	(108,028)	(95,855)
Other comprehensive income (loss) before reclassifications, net of tax	(138)	(143)
Amounts reclassified from accumulated other comprehensive income (loss), net of tax	736	719
Net current-period other comprehensive income (loss)	598	576
Ending balance	(107,430)	(95,279)
Short-Term Investments
Rollforward of Accumulated other comprehensive income (loss)
Beginning balance	804	(602)
Other comprehensive income (loss) before reclassifications, net of tax	378	614
Amounts reclassified from accumulated other comprehensive income (loss), net of tax	11	(74)
Net current-period other comprehensive income (loss)	389	540
Ending balance	1,193	(62)
Total
Rollforward of Accumulated other comprehensive income (loss)
Beginning balance	(103,883)	(93,140)
Net current-period other comprehensive income (loss)	1,331	2,261
Ending balance	$ (102,552)	$ (90,879)