CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE (LOSS) INCOME - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Comprehensive Income Net Of Tax Including Portion Attributable To Noncontrolling Interest [Abstract]
Net income	$ 3,635	$ 20,132	$ 31,269	$ 48,429
Foreign currency translation adjustment	(11,954)	(8,009)	(13,205)	(8,604)
Unrealized gain (loss) on defined benefit plan, net of tax	1,852	(4,991)	4,487	(5,541)
Unrealized foreign currency loss, net of tax	(343)	(779)	(444)	(329)
Comprehensive (loss) income	(6,810)	6,353	22,107	33,955
Less: Comprehensive income attributable to noncontrolling interest	798	705	2,222	1,415
Total comprehensive (loss) income attributable to common stockholders	$ (7,608)	$ 5,648	$ 19,885	$ 32,540