Accumulated Other Comprehensive Loss - Amounts Included in Accumulated Other Comprehensive Loss, Net of Tax (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance	$ 1,252,873
Other comprehensive loss before reclassifications	(33,210)
Amounts reclassified from accumulated other comprehensive loss	2,357
Other comprehensive loss	(30,853)	$ (37,955)
Ending balance	1,276,356	1,020,575
Accumulated Other Comprehensive Loss
Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance	(260,953)	(259,742)
Ending balance	(291,806)	$ (297,697)
Unrecognized Net Defined Benefit Plan Costs
Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance	(168,604)
Other comprehensive loss before reclassifications	0
Amounts reclassified from accumulated other comprehensive loss	1,878
Other comprehensive loss	1,878
Ending balance	(166,726)
Change in Fair Value of Derivatives
Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance	(4,656)
Other comprehensive loss before reclassifications	162
Amounts reclassified from accumulated other comprehensive loss	479
Other comprehensive loss	641
Ending balance	(4,015)
Foreign Currency Translation
Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance	(87,693)
Other comprehensive loss before reclassifications	(33,372)
Amounts reclassified from accumulated other comprehensive loss	0
Other comprehensive loss	(33,372)
Ending balance	$ (121,065)