CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Comprehensive Income Net Of Tax Including Portion Attributable To Noncontrolling Interest [Abstract]
Net income	$ 6,396	$ 15,858	$ 4,911	$ 27,634
Foreign currency translation adjustment	(10,673)	4,909	(7,792)	(1,251)
Unrealized (loss) gain on defined benefit plan, net of tax	(5,087)	4,448	(5,161)	2,635
Unrealized foreign currency gain (loss), net of tax	20	397	17	(101)
Comprehensive (loss) income	(9,344)	25,612	(8,025)	28,917
Less: Comprehensive income attributable to noncontrolling interest	(644)	(780)	(892)	(1,424)
Total comprehensive income (loss) attributable to common stockholders	$ (9,988)	$ 24,832	$ (8,917)	$ 27,493