Revenue Recognition - Additional Information (Detail)
|9 Months Ended|
Sep. 30, 2018
|Revenue From Contract With Customer [Abstract]|
|Deferred revenue, expected recognition period, description||The vast majority of our deferred revenue is related to subscription fees that are expected to be recognized as revenue within the next month.|
|Remaining deferred revenue, expected recognition period||12 months|
Description of timing for satisfying performance obligation in contract with customer. Includes, but is not limited to, as services are rendered, and upon shipment, delivery or completion of service.
Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
Period in which remaining performance obligation is expected to be recognized as revenue, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days.
Reference 1: http://www.xbrl.org/2003/role/disclosureRef