Revenue Recognition - Additional Information (Detail 1)	Apr. 30, 2019
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2019-05-01
Revenue Remaining Performance Obligation Expected Timing Of Satisfaction [Line Items]
Revenues remaining performance obligations expected to be satisfied period	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2020-05-01
Revenue Remaining Performance Obligation Expected Timing Of Satisfaction [Line Items]
Revenues remaining performance obligations expected to be satisfied period

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

Name:	us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionPeriod1
Namespace Prefix:	us-gaap_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	instant