Goodwill and Other Intangible Assets (Tables)
 12 Months Ended
Apr. 30, 2021
Goodwill and Intangible Assets Disclosure [Abstract]  
Schedule of Intangible Assets and Goodwill [Table Text Block]
The following table shows the changes in goodwill (which include no accumulated impairment losses) and other intangible assets over the past two years: 
GoodwillOther Intangible Assets
Balance as of April 30, 2019
$753 $645 
Acquisition of business (Note 12)11 12 
Foreign currency translation adjustment(8)(9)
Impairment— (13)
Balance as of April 30, 2020
756 635 
Sale of business (Note 12)(4)(1)
Acquisition of business (Note 12)8 8 
Foreign currency translation adjustment19 34 
Balance as of April 30, 2021
$779 $676