Consolidated Statements of Comprehensive Income (unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Statement of Comprehensive Income [Abstract]
Net income	$ 18,785	$ 24,135
Other comprehensive income, net of tax:
Currency translation adjustments (net of income tax of $0 in 2017 and 2016)	5,492	8,162
Change in unrecognized net periodic pension costs (net of income tax of $226 in 2017 and $171 in 2016)	236	238
Other (net of income tax of $0 in 2017 and 2016)	110	19
Total other comprehensive income, net of tax	5,838	8,419
Comprehensive Income (Loss), Net of Tax, Attributable to Parent	$ 24,623	$ 32,554