Consolidated Statements of Stockholders' Equity - USD ($)
$ in Millions
Total
Common Stock [Member]
Common stock, Class A, voting [Member]
Common Stock [Member]
Common Stock, Class B, nonvoting [Member]
Additional Paid-in Capital [Member]
Retained Earnings [Member]
AOCI Attributable to Parent [Member]
Treasury Stock, Common [Member]
Beginning Balance at Apr. 30, 2018 $ 1,316 $ 25 $ 47 $ 4 $ 1,730 $ (378) $ (112)
Increase (Decrease) in Stockholders' Equity [Roll Forward]              
Net income 835       835    
Net other comprehensive income (loss) 15         15  
Cash dividends (310)       (310)    
Acquisition of treasury stock (207)           (207)
Stock-based compensation expense 14     14      
Stock issued under compensation plans 19           19
Loss on issuance of treasury stock issued under compensation plans (30)     (18) (12)    
Other (5)       (5)    
Ending Balance at Apr. 30, 2019 1,647 25 47 0 2,238 (363) (300)
Increase (Decrease) in Stockholders' Equity [Roll Forward]              
Reclassification of tax effects [1]         43 (43)  
Net income 827       827    
Net other comprehensive income (loss) (141)         (141)  
Cash dividends (325)       (325)    
Acquisition of treasury stock (1)           (1)
Stock-based compensation expense 11     11      
Stock issued under compensation plans 43           43
Loss on issuance of treasury stock issued under compensation plans (86)     (11) (75)    
Ending Balance at Apr. 30, 2020 1,975 25 47 0 2,708 (547) (258)
Increase (Decrease) in Stockholders' Equity [Roll Forward]              
Net income 903       903    
Net other comprehensive income (loss) 125         125  
Cash dividends (338)       (338)    
Acquisition of treasury stock 0           0
Stock-based compensation expense 12     12      
Stock issued under compensation plans 21           21
Loss on issuance of treasury stock issued under compensation plans (42)     (12) (30)    
Ending Balance at Apr. 30, 2021 $ 2,656 $ 25 $ 47 $ 0 $ 3,243 $ (422) $ (237)
[1] Reflects adoption of Accounting Standards Update No. 2018-02, Reclassification of Certain Tax Effects from Accumulated Other Comprehensive Income (AOCI), effective May 1, 2019.