Product Warranties - Additional Information (Detail)		6 Months Ended
Jan. 01, 2017	Jun. 30, 2018
Product Warranty Liability [Line Items]
Product warranty period		2 years
Military Grade Products [Member]
Product Warranty Liability [Line Items]
Extended warranty period	3 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_ProductWarrantyLiabilityLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration