Organization and Summary of Significant Accounting Policies - Additional Information (Detail) $ in Thousands	3 Months Ended	9 Months Ended
Sep. 30, 2018 USD ($) subsidiary	Sep. 30, 2018 USD ($) subsidiary segment	Sep. 30, 2017 USD ($)	Dec. 31, 2017 USD ($)
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Number of wholly owned subsidiaries \| subsidiary	2	2
Number of reportable segments \| segment		2
Warranty period		1 year
Corporate owned life insurance policies fair value	$ 3,949	$ 3,949		$ 3,846
Impairment charge	$ 2,000	$ 0	$ (23)

Amount of write-down of assets recognized in the income statement. Includes, but is not limited to, losses from tangible assets, intangible assets and goodwill.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 28
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=109223946&loc=d3e3602-108585

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 360
-SubTopic 10
-Section 45
-Paragraph 4
-URI http://asc.fasb.org/extlink&oid=109226348&loc=d3e2420-110228

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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration