Consolidated Statements of Comprehensive Income (Parenthetical) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Statement of Comprehensive Income [Abstract]
Changes in net prior service credit and actuarial losses, tax (provision) benefit	$ (1,960)	$ 28,408	$ (42,822)
Change in fair value of derivatives, tax (provision)	(129)	(1,934)	(2,763)
Foreign currency translation, tax (provision) benefit	$ (9,949)	$ (14,027)	$ 4,580