Condensed Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Statement of Comprehensive Income [Abstract]
Net income	$ 70,316	$ 83,276	$ 145,866	$ 158,755
Other comprehensive income (loss), net of tax:
Changes in net prior service credit and actuarial losses	12	(225)	1,632	(769)
Change in fair value of derivatives	(277)	1,310	(107)	2,648
Foreign currency translation	(13,834)	(34,688)	(32,779)	(41,776)
Other comprehensive loss	(14,099)	(33,603)	(31,254)	(39,897)
Comprehensive income	$ 56,217	$ 49,673	$ 114,612	$ 118,858