Commitments and Contingencies - Activity Related to Asbestos Claims (Detail) - Asbestos Related Matters [Member] - Claim Claim in Thousands		12 Months Ended
		Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Number of Pending Claims [Roll Forward]
Pending claims - Beginning		37	62	79
New claims		4	4	4
Settlements		(1)	(1)	(2)
Dismissals	[1]	(10)	(28)	(19)
Pending claims - Ending		30	37	62
Inactive [Member]
Number of Pending Claims [Roll Forward]
Pending claims - Beginning		0	13
Pending claims - Ending		0	0	13
Active [Member]
Number of Pending Claims [Roll Forward]
Pending claims - Beginning		37	49
Pending claims - Ending		30	37	49

[1] (a)Inactive claims represent pending claims in Mississippi filed in 2004 or prior, which have been excluded from our asbestos measurement because the plaintiffs cannot demonstrate a significant compensable loss. As of December 31, 2016, all inactive claims have been dismissed.