v3.26.1
Stockholders' equity - Additional Information (Detail) - JPY (¥)
¥ / shares in Units, ¥ in Millions
12 Months Ended
Oct. 01, 2024
Mar. 31, 2026
Mar. 31, 2025
Mar. 31, 2024
Statements [Line Items]        
Number of shares of common stock authorized   18,000,000,000 18,000,000,000 3,600,000,000
Number of shares of treasury stock   242,143,391 124,806,850 39,783,003
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      
Dividends paid in kind   ¥ 955,700    
Board Resolution Two Thousand Twenty Five September Three [Member]        
Statements [Line Items]        
Dividends paid in kind   ¥ 955,700    
Dividends per share   ¥ 159.89    
Tranche One [Member]        
Statements [Line Items]        
Number of shares repurchased       798,000
Stock repurchase amount       ¥ 10,000
Tranche Two [Member]        
Statements [Line Items]        
Number of shares repurchased       14,869,300
Stock repurchase amount       ¥ 192,532
Tranche Three [Member]        
Statements [Line Items]        
Number of shares repurchased     572,400  
Stock repurchase amount     ¥ 7,468  
Tranche Four [Member]        
Statements [Line Items]        
Number of shares repurchased     93,287,300  
Stock repurchase amount     ¥ 250,000  
Tranche Five [Member]        
Statements [Line Items]        
Number of shares repurchased     7,715,800  
Stock repurchase amount     ¥ 27,930  
Tranche Six [Member]        
Statements [Line Items]        
Number of shares repurchased   6,921,900    
Stock repurchase amount   ¥ 22,069    
Tranche Seven [Member]        
Statements [Line Items]        
Number of shares repurchased   63,156,800    
Stock repurchase amount   ¥ 250,000    
Tranche Eight [Member]        
Statements [Line Items]        
Number of shares repurchased   70,793,900    
Stock repurchase amount   ¥ 250,000