v3.25.2
Financial instruments - Summary of Changes in Fair Value of Level 3 Assets and Liabilities (Detail) - JPY (¥)
¥ in Millions
 12 Months Ended
Mar. 31, 2025
Mar. 31, 2024
Assets:    
Beginning balance ¥ 34,107,490  
Ending balance 35,293,173 ¥ 34,107,490
Liabilities:    
Beginning balance 26,351,385  
Ending balance 26,783,022 26,351,385
Level 3 of fair value hierarchy [member] | Financial liabilities required to be measured at FVPL [member] | Contingent consideration [member] | Recurring fair value measurement [member]    
Liabilities:    
Beginning balance 50,343 51,512
Net income (3,013) 182
Other comprehensive income (260) 6,614
Purchases 3,101 4,363
Sales and settlements (24,221) (12,328)
Others [1] (165)  
Ending balance 25,785 50,343
Level 3 of fair value hierarchy [member] | Financial liabilities designated to be measured at FVPL [member] | Redeemable Non Controlling Interests [Member] | Recurring fair value measurement [member]    
Liabilities:    
Beginning balance 54,028 47,326
Net income (610) (3,396)
Other comprehensive income (348) 5,345
Purchases 6,199 5,294
Sales and settlements (6,306) (541)
Ending balance 52,963 54,028
Level 3 of fair value hierarchy [member] | Equity Contracts [Member] | Financial liabilities required to be measured at FVPL [member] | Derivatives [member] | Recurring fair value measurement [member]    
Liabilities:    
Net income 121,082  
Other comprehensive income (2,476)  
Ending balance 118,606  
Level 3 of fair value hierarchy [member] | Debt securities [member] | Japanese Corporate Bonds [Member] | Financial assets required to be measured at FVPL [member] | Recurring fair value measurement [member]    
Assets:    
Beginning balance 20 38
Purchases 33 20
Sales and settlements   (18)
Other (20) [1] (20)
Ending balance 33 20
Level 3 of fair value hierarchy [member] | Debt securities [member] | Japanese Corporate Bonds [Member] | Financial assets required to be measured at FVOCI [member] | Recurring fair value measurement [member]    
Assets:    
Beginning balance 138,848 171,622
Net income 9 8
Other comprehensive income (27,065) (32,782)
Ending balance 111,792 138,848
Level 3 of fair value hierarchy [member] | Debt securities [member] | Foreign Corporate Bonds [Member] | Financial assets required to be measured at FVPL [member] | Recurring fair value measurement [member]    
Assets:    
Beginning balance 2,933 3,377
Net income (53) 171
Purchases   317
Sales and settlements (31)  
Other   (932)
Ending balance 2,849 2,933
Level 3 of fair value hierarchy [member] | Debt securities [member] | Foreign Corporate Bonds [Member] | Financial assets designated to be measured at FVPL [member] | Recurring fair value measurement [member]    
Assets:    
Beginning balance 5,923 3,541
Net income 119 642
Purchases   1,740
Ending balance 6,042 5,923
Level 3 of fair value hierarchy [member] | Debt securities [member] | Foreign Corporate Bonds [Member] | Financial assets required to be measured at FVOCI [member] | Recurring fair value measurement [member]    
Assets:    
Beginning balance 34,757 24,672
Net income (939) 1,315
Other comprehensive income (452) 255
Purchases 48,023 29,150
Sales and settlements (17,628) (19,148)
Transfers out of Level 3 [2] (2,693) (1,487)
Ending balance 61,068 34,757
Level 3 of fair value hierarchy [member] | Debt securities [member] | Securitized Products [Member] | Financial assets required to be measured at FVOCI [member] | Recurring fair value measurement [member]    
Assets:    
Beginning balance 22,008 40,591
Net income (1,605) 1,483
Other comprehensive income 37 34
Purchases 40,906 7,905
Sales and settlements (12,468) (24,437)
Transfers out of Level 3   (3,568)
Ending balance 48,878 22,008
Level 3 of fair value hierarchy [member] | Debt securities [member] | Investment funds [member] | Financial assets required to be measured at FVPL [member] | Recurring fair value measurement [member]    
Assets:    
Beginning balance 67,355 60,796
Net income 2,580 3,781
Other comprehensive income (94) 736
Purchases 35,176 8,677
Sales and settlements (37,968) (6,635)
Other [1] (186)  
Ending balance 66,863 67,355
Level 3 of fair value hierarchy [member] | Equity securities [member] | Financial assets required to be measured at FVPL [member] | Recurring fair value measurement [member]    
Assets:    
Beginning balance 9,434 6,789
Net income (1,725) 595
Other comprehensive income (1) 1
Purchases 2,391 1,951
Sales and settlements (421) (152)
Other   250
Ending balance 9,678 9,434
Level 3 of fair value hierarchy [member] | Equity securities [member] | Financial assets designated to be measured at FVOCI [member] | Recurring fair value measurement [member]    
Assets:    
Beginning balance 249,181 324,028
Other comprehensive income (16,430) (6,987)
Purchases 7,200 6,342
Sales and settlements (2,185) (73,874)
Transfers out of Level 3 [2] (1,699) (1,175)
Other 66,421 [1] 847
Ending balance 302,488 249,181
Level 3 of fair value hierarchy [member] | Derivatives [member] | Equity Contracts [Member] | Financial assets required to be measured at FVPL [member] | Recurring fair value measurement [member]    
Assets:    
Beginning balance 2,379 4,692
Net income   (2,816)
Other comprehensive income (33) 503
Ending balance ¥ 2,346 ¥ 2,379
[1] The increase in equity securities designated to be measured at fair value through other comprehensive income is mainly due to a change in the scope of consolidation.
[2] Previously, the amount of transfers was calculated by assuming that transfers between levels occurred at the beginning of each quarterly consolidated accounting period. However, from the consolidated accounting period of the fiscal year ending March 31, 2025, the calculation of the amount of transfers has been changed to assume that transfers between levels occurred at the beginning of the interim consolidated accounting period. The amount of transfers between levels for the consolidated accounting period of the fiscal year ended March 31, 2024 is also calculated assuming that transfers between levels occurred at the beginning of the interim consolidated accounting period.