Condensed Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Statement Of Income And Comprehensive Income [Abstract]
Net income (loss)	$ (5,714)	$ 1,965	$ 5,889	$ 18,133
Foreign currency translation adjustments	27,504	(14,864)	33,569	(1,445)
Net change in:
Deferred (gains) losses on cash flow hedges, net of taxes of $1,632, $(258), $1,920 and $(201), respectively	(3,651)	944	(4,597)	1,010
Unrecognized retirement obligations net of taxes of $(1,430), $(1,442), $(2,678) and $(2,809), respectively	2,479	2,381	4,553	4,638
Other comprehensive income (loss)	26,332	(11,539)	33,525	4,203
Comprehensive income (loss)	$ 20,618	$ (9,574)	$ 39,414	$ 22,336