CONSOLIDATED STATEMENTS OF COMPREHENSIVE (LOSS) INCOME - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Comprehensive Income Net Of Tax Including Portion Attributable To Noncontrolling Interest [Abstract]
Net income	$ 18,477	$ 26,513	$ 65,633
Unrealized (loss) gain on defined benefit plan, net of tax	(7,777)	4,399	(7,555)
Unrealized gain on interest rate swap, net of tax	2,317
Unrealized foreign currency loss, net of tax	(22,790)	(20,413)	(16,473)
Comprehensive (loss) income	(9,773)	10,499	41,605
Less: Comprehensive income attributable to noncontrolling interest	(2,542)	(2,239)	(1,955)
Total comprehensive (loss) income attributable to common stockholders	$ (12,315)	$ 8,260	$ 39,650