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	$ 223,994	$ 269,659	$ 153,351
Other comprehensive income (loss), net of tax:
Changes in net prior service credit and net actuarial losses, net of tax benefit (provision) of $16,248, $3,017 and $(1,786), respectively	(49,644)	(6,293)	1,175
Change in fair value of derivatives, net of tax benefit (provision) of $283, $355 and $(906), respectively	(919)	(613)	1,528
Foreign currency translation, net of tax (provision) benefit of $(3,914), $17,131 and $(2,829), respectively	(29,272)	63,874	(17,753)
Other comprehensive (loss) income	(79,835)	56,968	(15,050)
Comprehensive income	$ 144,159	$ 326,627	$ 138,301