Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Statement of Comprehensive Income [Abstract]
Net Income	$ (212,327)	$ 166,398	$ 24,586
Other comprehensive income, net of tax:
Foreign currency translation adjustments	(47,026)	10,723	(5,559)
Pension-related adjustments	(215)	(195)	3,258
Other comprehensive income	(47,241)	10,528	(2,301)
Comprehensive Income	$ (259,568)	$ 176,926	$ 22,285