CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Comprehensive Income Net Of Tax Including Portion Attributable To Noncontrolling Interest [Abstract]
Net income	$ 26,513	$ 65,633	$ 24,104
Foreign currency translation adjustment	(19,996)	(15,705)	6,671
Unrealized gain (loss) on defined benefit plan, net of tax	4,399	(7,555)	(16,971)
Unrealized foreign currency loss, net of tax	(417)	(768)	(218)
Comprehensive income	10,499	41,605	13,586
Less: Comprehensive (income) loss attributable to noncontrolling interest	(2,239)	(1,955)	2,428
Total comprehensive income attributable to common stockholders	$ 8,260	$ 39,650	$ 16,014