v3.26.1
Financial instruments - Summary of Changes in Fair Value of Level 3 Assets and Liabilities (Detail) - JPY (¥)
¥ in Millions
 12 Months Ended
Mar. 31, 2026
Mar. 31, 2025
Assets:    
Beginning balance ¥ 35,293,173  
Ending balance 15,683,490 ¥ 35,293,173
Liabilities:    
Beginning balance 26,783,022  
Ending balance 7,169,901 26,783,022
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 25,785 50,343
Net income [1],[2] (873) (3,013)
Other comprehensive income [1],[3] 1,480 (260)
Purchases 1,271 3,101
Sales and settlements (10,933) (24,221)
Others (181) [4] (165) [5]
Ending balance 16,549 25,785
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 52,963 54,028
Net income [1],[2] 2,865 (610)
Other comprehensive income [1],[3] 3,472 (348)
Purchases 20,360 6,199
Sales and settlements (1,092) (6,306)
Ending balance 78,568 52,963
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:    
Beginning balance 118,606  
Net income [1],[2] (67,174) 121,082
Other comprehensive income [1],[3] 4,231 (2,476)
Ending balance 55,663 118,606
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 33 20
Net income (9)  
Purchases 26 33
Other 120 [4] (20) [5]
Ending balance 170 33
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 111,792 138,848
Net income [1],[2] 4 9
Other comprehensive income [1],[3] (17,509) (27,065)
Other [4] (94,287)  
Ending balance   111,792
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 2,849 2,933
Net income [1],[2] 201 (53)
Purchases 3,551  
Sales and settlements 0 (31)
Ending balance 6,601 2,849
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 6,042 5,923
Net income [1],[2] 74 119
Transfers out of Level 3 (1,808)  
Other [4] (4,308)  
Ending balance   6,042
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 61,068 34,757
Net income [1],[2] 727 (939)
Other comprehensive income [1],[3] 70 (452)
Purchases 29,629 48,023
Sales and settlements (16,921) (17,628)
Transfers out of Level 3 [6] 0 (2,693)
Other [4] (74,573)  
Ending balance   61,068
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 48,878 22,008
Net income [1],[2] 154 (1,605)
Other comprehensive income [1],[3] 19 37
Purchases 31,207 40,906
Sales and settlements (4,816) (12,468)
Transfers out of Level 3 (12,650)  
Other [4] (62,792)  
Ending balance   48,878
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 66,863 67,355
Net income [1],[2] (2,296) 2,580
Other comprehensive income [1],[3] 399 (94)
Purchases 3,873 35,176
Sales and settlements (2,302) (37,968)
Other (49,891) [4] (186) [5]
Ending balance 16,646 66,863
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 9,678 9,434
Net income [1],[2] 401 (1,725)
Other comprehensive income [1],[3] 1 (1)
Purchases 7,067 2,391
Sales and settlements (160) (421)
Other [4] (1,958)  
Ending balance 15,029 9,678
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 302,488 249,181
Other comprehensive income [1],[3] (11,154) (16,430)
Purchases 31,126 7,200
Sales and settlements (3,005) (2,185)
Transfers out of Level 3 [6]   (1,699)
Other (503) [4] 66,421 [5]
Ending balance 318,952 302,488
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 2,346 2,379
Net income (2,119)  
Other comprehensive income [1],[3] 20 (33)
Sales and settlements ¥ (247)  
Ending balance   ¥ 2,346
[1] For liability items, gains are presented as negative and losses are presented as positive.
[2] Gains (losses) recognized in net income are included in other operating (income) expense, net, financial income, financial expenses and net income (loss) from discontinued operations in the consolidated statements of income. In connection with the Resolution for the plan regarding the execution of the Partial Spin-off of the Financial Services business, the Financial Services business was classified as a discontinued operation. Therefore, income and loss from the Financial Services business is included in net income (loss) from discontinued operations, which was previously included in financial services revenue in the consolidated statements of income.
[3] Gains (losses) recognized in other comprehensive income are included in changes in equity instruments measured at fair value through other comprehensive income, exchange differences on translating foreign operations and other comprehensive income from discontinued operations in the consolidated statements of comprehensive income. In connection with the Resolution for the plan regarding the execution of the Partial Spin-off of the Financial Services business, the Financial Services business was classified as a discontinued operation. Therefore, other comprehensive income from the Financial Services business, which was previously included in changes in equity instruments measured at fair value through other comprehensive income and changes in debt instruments measured at fair value through other comprehensive income in the consolidated statements of comprehensive income, is included in other comprehensive income from discontinued operations.
[4] This column primarily includes the amount excluded from consolidation as a result of the execution of the Partial Spin-off of the Financial Services business.
[5] This column primarily includes the amount of equity securities designated to be measured at fair value through other comprehensive income due to a change in the scope of consolidation.
[6] Certain financial assets were transferred from Level 3 because observable market data became available.