Annual report pursuant to Section 13 and 15(d)

Segments - Additional Information (Detail)

v3.19.2
Segments - Additional Information (Detail) - Segment
12 Months Ended
Apr. 30, 2019
Apr. 30, 2018
Apr. 30, 2017
Segment Reporting Information [Line Items]      
Number of global segments 3 3  
Geographic Concentration Risk | Sales Revenue, Net [Member] | UNITED STATES | Minimum      
Segment Reporting Information [Line Items]      
Concentration risk percentage 10.00% 10.00% 10.00%
Geographic Concentration Risk | Sales Revenue, Net [Member] | United Kingdom | Minimum      
Segment Reporting Information [Line Items]      
Concentration risk percentage 10.00% 10.00% 10.00%
Geographic Concentration Risk | Property, Plant and Equipment | UNITED STATES | Minimum      
Segment Reporting Information [Line Items]      
Concentration risk percentage 10.00% 10.00% 10.00%