Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Statement Of Income And Comprehensive Income [Abstract]
Net income	$ 21,554	$ 64,575	$ 69,246
Foreign currency translation adjustments	(27,407)	(38,817)	(49,365)
Net change in:
Deferred gains (losses) on cash flow hedges, net of taxes of $(335), $880 and $(1,281), respectively	1,725	(2,581)	3,297
Unrecognized retirement obligations, net of taxes of $(7,247), $(2,920) and $20,730, respectively	11,562	5,782	(33,445)
Other comprehensive loss	(14,120)	(35,616)	(79,513)
Comprehensive income (loss)	$ 7,434	$ 28,959	$ (10,267)