Goodwill and Long-Lived Assets - Changes in Carrying Amount of Goodwill by Reporting Unit (Detail) - USD ($) $ in Thousands		12 Months Ended
	Dec. 31, 2016	Dec. 31, 2017	Dec. 31, 2016
Goodwill [Roll Forward]
Beginning Balance		$ 63,606	$ 16,841
Goodwill addition / adjustment		323	47,987
Currency translation adjustment		5,040	(1,222)
Ending Balance	$ 63,606	68,969	63,606
Performance Materials
Goodwill [Roll Forward]
Beginning Balance		12,777	12,898
Goodwill addition / adjustment		0	0
Currency translation adjustment		530	(121)
Ending Balance	12,777	13,307	12,777
Technical Nonwovens
Goodwill [Roll Forward]
Beginning Balance		50,829	3,943
Goodwill addition / adjustment	300	323	47,987
Currency translation adjustment		4,510	(1,101)
Ending Balance	$ 50,829	$ 55,662	$ 50,829