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]
Foreign currency translation, tax	$ 10,977	$ 24,150	$ 24,818
Prior service cost recognized in net periodic cost, tax	20	0	(9)
Unamortized (loss) gain arising during the period, tax	1,849	1,469	26,624
Net loss recognized in net periodic cost, tax	(2,489)	(2,242)	(1,544)
Foreign currency translation, tax	(373)	(316)	(265)
Unrealized gain (loss) on derivatives arising during the period, tax	1,359	379	(111)
Reclassification adjustment on derivatives included in net income, tax	$ (1,010)	$ (196)	$ 111