Condensed Consolidated Statements of Comprehensive Income (Loss) (Unaudited) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Statement of Comprehensive Income [Abstract]
Net income (loss)	$ 24,540	$ (4,607)	$ 45,306	$ (8,608)
Other comprehensive income (loss) - net of tax:
Adjustment to accrued pension liability	618	487	1,615	1,715
Change in unrealized net (loss) gain on foreign currency	(2,953)	709	(9,149)	4,339
Unrealized gain on cash flow hedge derivatives	82	205	322	61
Other comprehensive (loss) income	(2,253)	1,401	(7,212)	6,115
Total comprehensive income (loss)	$ 22,287	$ (3,206)	$ 38,094	$ (2,493)