Commitments and Contingencies - Activity Related to Asbestos Claims (Detail) - Asbestos Related Matters [Member] - Claim Claim in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Number of Pending Claims [Roll Forward]
Pending claims - Beginning	30	37	62
New claims	4	4	4
Settlements	(2)	(1)	(1)
Dismissals	(6)	(10)	(28)
Pending claims - Ending	26	30	37
Active [Member]
Number of Pending Claims [Roll Forward]
Pending claims - Ending	26