Basis of Presentation and Summary of Significant Accounting Policies - Revenue, Additional Information (Detail)	12 Months Ended
Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Transferred at Point in Time
Disaggregation of Revenue [Line Items]
Revenues, percent	92.50%	92.40%	94.00%
Transferred over Time
Disaggregation of Revenue [Line Items]
Revenues, percent	7.50%	7.60%	6.00%

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