Condensed Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Statement of Comprehensive Income [Abstract]
Net income	$ 81,274	$ 84,739	$ 158,970	$ 185,802
Other comprehensive income (loss), net of tax:
Changes in net prior service credit and actuarial losses	2,625	807	7,745	2,441
Change in fair value of derivatives	(159)	476	(2,647)	673
Foreign currency translation	(25,016)	(4,576)	(24,213)	(26,397)
Other comprehensive loss	(22,550)	(3,293)	(19,115)	(23,283)
Comprehensive income	$ 58,724	$ 81,446	$ 139,855	$ 162,519