v3.26.1
Financial instruments - Summary of Changes in Unrealized Gains (Losses) Recognized in Net Income for Level 3 Assets and Liabilities (Detail) - Recurring fair value measurement [member] - Level 3 of fair value hierarchy [member] - JPY (¥)
¥ in Millions
 12 Months Ended
Mar. 31, 2026
Mar. 31, 2025
Contingent Considerations [Member] | Financial liabilities required to be measured at FVPL [member]    
Liabilities:    
Financial liabilities required to be measured at FVPL ¥ (524) ¥ (1,223)
Redeemable Non Controlling Interests [Member] | Financial liabilities designated to be measured at FVPL [member]    
Liabilities:    
Financial liabilities required to be measured at FVPL (2,865) 600
Equity Contracts [Member] | Financial liabilities required to be measured at FVPL [member]    
Liabilities:    
Financial liabilities required to be measured at FVPL 67,174 (121,082)
Debt securities [member] | Investment funds [member] | Financial assets required to be measured at FVPL [member]    
Assets:    
Financial assets (2,067) (1,801)
Debt securities [member] | Foreign Corporate Bonds [Member] | Financial assets required to be measured at FVPL [member]    
Assets:    
Financial assets 201 (39)
Debt securities [member] | Foreign Corporate Bonds [Member] | Financial assets designated to be measured at FVPL [member]    
Assets:    
Financial assets 0 119
Debt securities [member] | Foreign Corporate Bonds [Member] | Financial assets required to be measured at FVOCI [member]    
Assets:    
Financial assets 0 (939)
Debt securities [member] | Securitized Products [Member] | Financial assets required to be measured at FVOCI [member]    
Assets:    
Financial assets 0 (1,610)
Debt securities [member] | Japanese Corporate Bonds [Member] | Financial assets required to be measured at FVPL [member]    
Assets:    
Financial assets (9)  
Debt securities [member] | Japanese Corporate Bonds [Member] | Financial assets required to be measured at FVOCI [member]    
Assets:    
Financial assets 0 9
Equity securities [member] | Financial assets required to be measured at FVPL [member]    
Assets:    
Financial assets ¥ 319 ¥ (840)