Warranty Costs - Additional Information (Detail)	9 Months Ended
Sep. 30, 2018
Minimum [Member]
Guarantor Obligations [Line Items]
Product warranty period	3 months
Maximum [Member]
Guarantor Obligations [Line Items]
Product warranty period	2 years

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

No definition available.

Name:	us-gaap_GuaranteeObligationsLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration