Commitments and Contingencies - Additional Information (Detail)	6 Months Ended
Jun. 30, 2018 USD ($)
Commitments and Contingencies Disclosure [Abstract]
Accrual for the probable payment of pending claims	$ 49,195,000
Payments for legal settlements	$ 27,250,000

The amount of cash paid for the settlement of litigation or for other legal issues during the period.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 25
-Subparagraph (g)
-URI http://asc.fasb.org/extlink&oid=109223946&loc=d3e3536-108585

Name:	us-gaap_PaymentsForLegalSettlements
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration