v3.25.2
Stockholders' equity - Additional Information (Detail) - JPY (¥)
¥ in Millions
12 Months Ended
Oct. 01, 2024
Mar. 31, 2025
Mar. 31, 2024
Mar. 31, 2023
Statements [Line Items]        
Number of shares of common stock authorized   18,000,000,000 3,600,000,000 3,600,000,000
Number of shares of treasury stock   124,806,850 39,783,003 26,584,221
Percentage of cash dividends from retained earnings appropriated as a capital reserve or a legal reserve   10.00% 10.00% 10.00%
Percentage of ordinary shares used to obtain aggregated amount of capital reserve and legal reserve   25.00% 25.00% 25.00%
Minimum threshold percentage of additional paid in capital or proceeds from issuance of shares incorporated in common stock specified by The Companies Act of Japan   50.00% 50.00% 50.00%
Shareholders stock split five-for-one      
Tranche One [Member]        
Statements [Line Items]        
Number of shares repurchased     798,000 8,545,600
Stock repurchase amount     ¥ 10,000 ¥ 89,118
Tranche Two [Member]        
Statements [Line Items]        
Number of shares repurchased   572,400 14,869,300  
Stock repurchase amount   ¥ 7,468 ¥ 192,532  
Tranche Three [Member]        
Statements [Line Items]        
Number of shares repurchased   93,287,300    
Stock repurchase amount   ¥ 250,000    
Tranche Four [Member]        
Statements [Line Items]        
Number of shares repurchased   7,715,800    
Stock repurchase amount   ¥ 27,930