Accumulated Other Comprehensive Loss - Amounts Included in Accumulated Other Comprehensive Loss, Net of Tax (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance			$ 1,252,873
Other comprehensive loss before reclassifications			(37,633)
Amounts reclassified from accumulated other comprehensive loss			7,428
Other comprehensive (loss) income	$ (27,725)	$ 25,008	(30,205)	$ (12,610)
Ending balance	1,456,706	1,218,863	1,456,706	1,218,863
Accumulated Other Comprehensive Loss
Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance	(263,433)	(297,360)	(260,953)	(259,742)
Ending balance	(291,158)	$ (272,352)	(291,158)	$ (272,352)
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			5,910
Other comprehensive (loss) income			5,910
Ending balance	(162,694)		(162,694)
Change in Fair Value of Derivatives
Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance			(4,656)
Other comprehensive loss before reclassifications			1,022
Amounts reclassified from accumulated other comprehensive loss			1,518
Other comprehensive (loss) income			2,540
Ending balance	(2,116)		(2,116)
Foreign Currency Translation
Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance			(87,693)
Other comprehensive loss before reclassifications			(38,655)
Amounts reclassified from accumulated other comprehensive loss			0
Other comprehensive (loss) income			(38,655)
Ending balance	$ (126,348)		$ (126,348)