Annual report pursuant to Section 13 and 15(d)

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

v2.4.0.6
Basic and Diluted Earnings Per Share - Additional Information (Detail)
In Millions, unless otherwise specified
12 Months Ended
Apr. 30, 2013
Apr. 30, 2012
Apr. 30, 2011
Earnings Per Share Disclosure [Line Items]      
Anti-dilutive securities excluded from computation of earnings per share, shares 0.50 0.57 0.39