Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Statement of Comprehensive Income [Abstract]
Net income	$ 172,413	$ 182,391	$ 185,413
Other comprehensive income (loss), net of tax:
Changes in net prior service credit and actuarial losses, net of tax (provision) benefit of $(1,960), $28,408 and $(42,822), respectively	4,972	(50,331)	66,754
Change in fair value of derivatives, net of tax (provision) of $(129), $(1,934) and $(2,763), respectively	210	2,592	3,937
Foreign currency translation, net of tax (provision) benefit of $(9,949), $(14,027) and $4,580, respectively	(48,364)	(79,766)	1,103
Other comprehensive (loss) income	(43,182)	(127,505)	71,794
Comprehensive income	$ 129,231	$ 54,886	$ 257,207