v3.26.1
Share-based Payments - Narrative (Details)
¥ / shares in Units, ¥ in Millions
12 Months Ended
Jan. 08, 2019
Mar. 31, 2026
JPY (¥)
shares
plan
¥ / shares
Mar. 31, 2025
JPY (¥)
shares
¥ / shares
Mar. 31, 2024
JPY (¥)
¥ / shares
Mar. 31, 2023
¥ / shares
Disclosure of terms and conditions of share-based payment arrangement [line items]          
Share-based compensation cost (reversal of cost)   ¥ 73,300 ¥ 73,585 ¥ 71,510  
Stock options granted (in shares) | shares   0 0    
Weighted-average share price for share options exercised (in JPY per share) | ¥ / shares   ¥ 5,247 ¥ 4,167 ¥ 4,540  
Weighted-average exercise price of share options outstanding (in JPY per share) | ¥ / shares   ¥ 4,166 ¥ 4,138 ¥ 4,136 ¥ 4,111
Weighted-average remaining contractual life of share options outstanding   6 years 7 years 8 years  
Number of plans | plan   3      
American depositary shares | Shire          
Disclosure of terms and conditions of share-based payment arrangement [line items]          
Ratio of award or share per common stock 0.5        
Liability-settled long-term incentive plan (LTIP)          
Disclosure of terms and conditions of share-based payment arrangement [line items]          
Ratio of award or share per common stock   1      
BIP          
Disclosure of terms and conditions of share-based payment arrangement [line items]          
Weighted average remaining contractual life   1 year 1 year    
ESOP          
Disclosure of terms and conditions of share-based payment arrangement [line items]          
Weighted average remaining contractual life   1 year 1 year    
Equity-Settled LTIP          
Disclosure of terms and conditions of share-based payment arrangement [line items]          
Weighted average remaining contractual life   1 year 1 year    
BIP, ESOP and Equity-Settled LTIP          
Disclosure of terms and conditions of share-based payment arrangement [line items]          
Share-based compensation cost (reversal of cost)   ¥ 72,775 ¥ 72,867 ¥ 70,871  
Stock options          
Disclosure of terms and conditions of share-based payment arrangement [line items]          
Vesting period   3 years      
Stock options | Directors          
Disclosure of terms and conditions of share-based payment arrangement [line items]          
Expiration term   10 years      
Stock options | Corporate officers and senior management          
Disclosure of terms and conditions of share-based payment arrangement [line items]          
Expiration term   20 years      
Restricted stock units (RSUs)          
Disclosure of terms and conditions of share-based payment arrangement [line items]          
Award vesting percentage   33.33% 33.33% 33.33%  
Restricted stock units (RSUs) | BIP          
Disclosure of terms and conditions of share-based payment arrangement [line items]          
Vesting period   3 years      
Restricted stock units (RSUs) | Equity-Settled LTIP          
Disclosure of terms and conditions of share-based payment arrangement [line items]          
Vesting period   3 years      
Performance stock units (PSUs) | BIP          
Disclosure of terms and conditions of share-based payment arrangement [line items]          
Vesting period   3 years      
Performance stock units (PSUs) | ESOP          
Disclosure of terms and conditions of share-based payment arrangement [line items]          
Vesting period   3 years      
Performance stock units (PSUs) | Equity-Settled LTIP          
Disclosure of terms and conditions of share-based payment arrangement [line items]          
Vesting period   3 years      
Phantom stock appreciation rights and restricted stock units          
Disclosure of terms and conditions of share-based payment arrangement [line items]          
Share-based compensation cost (reversal of cost)   ¥ 525 ¥ 717 ¥ 639  
Liabilities from share-based payment transactions   ¥ 662 ¥ 642 ¥ 1,018  
Phantom stock appreciation rights (PSARs)          
Disclosure of terms and conditions of share-based payment arrangement [line items]          
Vesting period   3 years      
Expiration term   10 years      
Award vesting percentage   33.33% 33.33% 33.33%