Litigation - Schedule of Loss Contingencies by Contingency (Detail) - Asbestos Claims [Member]	6 Months Ended
	Jun. 30, 2018 USD ($) Claim	Jun. 30, 2017 USD ($) Claim
Loss Contingencies [Line Items]
Total claims pending at the beginning of the period	6,907	6,618
New claims served	627	709
Claims dismissed	(198)	(185)
Claims settled	(190)	(176)
Total claims pending at the end of the period	7,146	6,966
Gross settlement and defense costs | $	$ 12,446,000	$ 12,266,000
Avg. gross settlement and defense costs per claim resolved | $	$ 32,080	$ 33,980