Postretirement Benefits Other Than Pensions - Additional Information (Detail) $ in Thousands	12 Months Ended
	Dec. 31, 2017 USD ($) Location	Dec. 31, 2016 USD ($)
Other Postretirement Benefits Plan [Member]
Payment for Pension and Other Postretirement Benefits [Abstract]
Other post retirement benefits recorded in consolidated balance sheets	$ 5,587	$ 4,592
Number of locations | Location	2
Domestic Plan [Member]
Payment for Pension and Other Postretirement Benefits [Abstract]
Unrecognized prior service credits	$ (676)	(970)
Unrecognized actuarial gains, before tax	(13,930)	(16,572)
Foreign Plan [Member]
Payment for Pension and Other Postretirement Benefits [Abstract]
Unrecognized prior service credits	(714)	(940)
Unrecognized actuarial gains, before tax	$ 9,127	$ 4,926