Annual report pursuant to Section 13 and 15(d)

Basic and Diluted Earnings Per Share - Additional Information (Detail)

v3.7.0.1
Basic and Diluted Earnings Per Share - Additional Information (Detail) - shares
shares in Millions
12 Months Ended
Apr. 30, 2017
Apr. 30, 2016
Apr. 30, 2015
Restricted Stock      
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]      
Anti-dilutive securities excluded from computation of earnings per share, shares 0.5 0.6 0.5