Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Statement of Comprehensive Income [Abstract]
Net income	$ 108,787	$ 103,409	$ 66,503
Other comprehensive income (loss), net of tax:
Currency translation adjustments (net of income tax of $0 in 2016, 2015 and 2014)	(15,017)	(27,581)	(29,539)
Change in unrecognized net periodic pension costs (net of income tax of $343 in 2016, $90 in 2015, and $2,361 in 2014)	(727)	(159)	(3,844)
Other (net of income tax of $0 in 2016 and 2015, $72 in 2014)	86	(84)	(186)
Other comprehensive income (loss)	(15,658)	(27,824)	(33,569)
Comprehensive income	$ 93,129	$ 75,585	$ 32,934