Unearned Revenue By Segment (Detail) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Deferred Revenue Arrangement [Line Items]
Unearned revenue	$ 6,128	$ 4,889
Automotive Segments
Deferred Revenue Arrangement [Line Items]
Unearned revenue	1,914
Industrial Segments
Deferred Revenue Arrangement [Line Items]
Unearned revenue	$ 4,214	$ 4,889

Amount of deferred revenue as of balance sheet date. Deferred revenue represents collections of cash or other assets related to a revenue producing activity for which revenue has not yet been recognized. Generally, an entity records deferred revenue when it receives consideration from a customer before achieving certain criteria that must be met for revenue to be recognized in conformity with GAAP.

No definition available.

Name:	us-gaap_DeferredRevenue
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant