Consolidated Statements of Comprehensive Income (Parenthetical) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Statement of Comprehensive Income [Abstract]
Changes in net prior service credit and actuarial losses, tax (provision) benefit	$ (1,786)	$ (1,960)	$ 28,408
Change in fair value of derivatives, tax (provision)	(906)	(129)	(1,934)
Foreign currency translation, tax (provision)	$ (2,829)	$ (9,949)	$ (14,027)