Litigation - Schedule of Loss Contingencies by Contingency (Detail) - Asbestos Claims [Member]	12 Months Ended
	Dec. 31, 2017 USD ($) Claim	Dec. 31, 2016 USD ($) Claim
Loss Contingencies [Line Items]
Total claims pending at the beginning of the period	6,618	6,212
New claims served	1,365	1,452
Claims dismissed	(718)	(782)
Claims settled	(358)	(264)
Total claims pending at the end of the period	6,907	6,618
Gross settlement and defense costs | $	$ 21,431,000	$ 17,960,000
Average gross settlement and defense costs per claim resolved | $	$ 19,920	$ 17,170