Revenue - Additional Information (Detail) $ in Millions	9 Months Ended
Sep. 30, 2018 USD ($)
Revenue from Contract with Customer [Abstract]
Revenue remaining performance obligation	$ 49.0
Revenue remaining performance obligation description	The Company discloses only the transaction price allocated to its remaining performance obligations on contracts with an original duration greater than one year

Description of when remaining performance obligation is expected to be recognized as revenue.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 13
-Subparagraph (b)(2)
-URI http://asc.fasb.org/extlink&oid=109196051&loc=SL49130556-203045

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