Segment Disclosure - Additional information (Detail)	3 Months Ended	12 Months Ended
Jan. 31, 2019 Segment Customer	Jan. 31, 2018 Customer	Oct. 31, 2018 Segment
Segment Reporting Information [Line Items]
Number of reportable operating segment \| Segment	2		1
Customer concentration risk \| Sales revenue
Segment Reporting Information [Line Items]
Number of major customers \| Customer	1	1

Number of segments reported by the entity. A reportable segment is a component of an entity for which there is an accounting requirement to report separate financial information on that component in the entity's financial statements.

No definition available.

Name:	us-gaap_NumberOfReportableSegments
Namespace Prefix:	us-gaap_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration