Condensed Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Statement Of Income And Comprehensive Income [Abstract]
Net income	$ 65,281	$ 64,398	$ 192,605	$ 164,242
Other comprehensive (loss) income:
Foreign currency translation adjustments	(2,627)	(6,830)	(15,014)	(7,269)
Income tax effect	(101)	156	44	790
Foreign currency translation adjustments, net	(2,728)	(6,674)	(14,970)	(6,479)
Pension and other post-retirement adjustments	(30)	300	(262)	203
Income tax effect	13	(80)	75	(67)
Pension and other post-retirement adjustments, net	(17)	220	(187)	136
Other comprehensive (loss) income, net of tax	(2,745)	(6,454)	(15,157)	(6,343)
Comprehensive income	$ 62,536	$ 57,944	$ 177,448	$ 157,899

Amount after tax of increase (decrease) in equity from transactions and other events and circumstances from net income and other comprehensive income, attributable to parent entity. Excludes changes in equity resulting from investments by owners and distributions to owners.

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Amount before tax, after reclassification adjustments of gain (loss) on foreign currency translation adjustments, foreign currency transactions designated and effective as economic hedges of a net investment in a foreign entity and intra-entity foreign currency transactions that are of a long-term-investment nature.

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