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 Comprehensive Income [Abstract]
Net Income	$ 29,831	$ 28,176	$ 81,682	$ 71,342
Other comprehensive income (loss), net of tax:
Currency translation adjustments (net of income tax of $0 in 2016 and 2015)	1,401	2,054	2,443	(19,281)
Change in unrecognized net periodic pension costs (net of income tax of $194 and $532 in 2016 and $117 and $402 in 2015)	218	284	701	802
Other (net of income tax of $0 in 2016 and 2015)	82	(105)	119	(75)
Total other comprehensive income (loss), net of tax	1,701	2,233	3,263	(18,554)
Comprehensive income	$ 31,532	$ 30,409	$ 84,945	$ 52,788