Significant Accounting Policies - Tooling Related Assets (Detail) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Accounting Policies [Line Items]
Total tooling related assets	$ 18,821	$ 9,646
Inventories, net of progress billings and reserves
Accounting Policies [Line Items]
Total tooling related assets	18,540	9,388
Prepaid expenses and other current assets
Accounting Policies [Line Items]
Total tooling related assets	$ 281	$ 258

Carrying amount as of the balance sheet date of capitalized costs of molds, dies, and other tools that will be used in producing products under a long-term supply arrangement.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 340
-SubTopic 10
-Section 25
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=6387057&loc=d3e6169-108318

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 340
-SubTopic 10
-Section S99
-Paragraph 3
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=27011391&loc=d3e105117-122735

Name:	us-gaap_PreproductionCostsRelatedToLongTermSupplyArrangementsAssetForMoldsDiesAndToolsOwned
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant