Industry Segments - Additional Information (Detail)	3 Months Ended
Jul. 31, 2018 Segment Group
Segment Reporting [Abstract]
Number of major operating segments \| Segment	3
Number of major product and service groups \| Group	6
Segment reporting, disclosure of major customers	No one customer accounted for more than 10% of total revenues for the three months ended July 31, 2018 and 2017.

Disclosure of the extent of enterprise reliance on its major customers. For example, includes revenues from transactions with a single external customer amounting to 10 percent or more of the entity's revenues, the total amount of revenues from each such customer, and the identity of the segment or segments reporting the revenues. A group of entities that the entity knows to be under common control generally will be considered a single customer for inclusion in this item. The federal government, a state government, a local government (for example, a county or municipality), or a foreign government each will generally be considered as a single customer for inclusion in this item.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 42
-URI http://asc.fasb.org/extlink&oid=115929826&loc=d3e9054-108599

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