Accumulated Other Comprehensive Loss - Amounts Included in Accumulated Other Comprehensive Loss, Net of Tax (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Other Comprehensive Income (Loss) [Roll Forward]
Balance at December 31, 2019			$ (259,742)
Other comprehensive loss before reclassifications			(42,079)
Amounts reclassified from accumulated other comprehensive loss			4,461
Other comprehensive loss	$ 337	$ 7,058	(37,618)	$ 3,435
Balance at June 30, 2020	(297,360)	$ (265,373)	(297,360)	$ (265,373)
Unrecognized Net Defined Benefit Plan Costs [Member]
Other Comprehensive Income (Loss) [Roll Forward]
Balance at December 31, 2019			(139,102)
Other comprehensive loss before reclassifications			(872)
Amounts reclassified from accumulated other comprehensive loss			3,620
Other comprehensive loss			2,748
Balance at June 30, 2020	(136,354)		(136,354)
Change in Fair Value of Derivatives [Member]
Other Comprehensive Income (Loss) [Roll Forward]
Balance at December 31, 2019			(3,182)
Other comprehensive loss before reclassifications			(3,192)
Amounts reclassified from accumulated other comprehensive loss			841
Other comprehensive loss			(2,351)
Balance at June 30, 2020	(5,533)		(5,533)
Foreign Currency Translation [Member]
Other Comprehensive Income (Loss) [Roll Forward]
Balance at December 31, 2019			(117,458)
Other comprehensive loss before reclassifications			(38,015)
Amounts reclassified from accumulated other comprehensive loss			0
Other comprehensive loss			(38,015)
Balance at June 30, 2020	$ (155,473)		$ (155,473)