v3.25.2
Financial instruments - Summary of Assets and Liabilities that are Measured at Fair Value on a Recurring Basis (Detail) - JPY (¥)
¥ in Millions
Mar. 31, 2025
Mar. 31, 2024
Contingent consideration [member]    
Liabilities:    
Financial liabilities required to be measured at FVPL ¥ 25,785 ¥ 50,343
Redeemable Non Controlling Interests [Member]    
Liabilities:    
Financial liabilities designated to be measured at FVPL 52,963 54,028
Recurring fair value measurement [member]    
Assets:    
Total assets 15,860,946 16,013,706
Liabilities:    
Total liabilities 233,274 133,658
Recurring fair value measurement [member] | Contingent consideration [member]    
Liabilities:    
Financial liabilities required to be measured at FVPL 25,785 50,343
Recurring fair value measurement [member] | Redeemable Non Controlling Interests [Member]    
Liabilities:    
Financial liabilities designated to be measured at FVPL 52,963 54,028
Recurring fair value measurement [member] | Interest rate swap contract [member] | Derivative Liabilities [Member]    
Liabilities:    
Financial liabilities required to be measured at FVPL 15,835 6,450
Recurring fair value measurement [member] | Foreign Exchange Contracts [Member] | Derivative Liabilities [Member]    
Liabilities:    
Financial liabilities required to be measured at FVPL 15,778 17,493
Recurring fair value measurement [member] | Equity Contracts [Member] | Derivative Liabilities [Member]    
Liabilities:    
Financial liabilities required to be measured at FVPL 119,120 5,344
Recurring fair value measurement [member] | Bond Contracts [Member] | Derivative Liabilities [Member]    
Liabilities:    
Financial liabilities required to be measured at FVPL 3,793  
Recurring fair value measurement [member] | Debt securities [member] | Japanese National Government Bonds [Member]    
Assets:    
Financial assets required to be measured at FVPL 411,764 423,129
Financial assets designated to be measured at FVPL 757,357 1,021,309
Financial assets required to be measured at FVOCI 6,134,141 7,057,395
Recurring fair value measurement [member] | Debt securities [member] | Japanese local government bonds [Member]    
Assets:    
Financial assets required to be measured at FVPL 1,225 1,846
Financial assets designated to be measured at FVPL 8,596 13,945
Financial assets required to be measured at FVOCI 71,752 48,712
Recurring fair value measurement [member] | Debt securities [member] | Japanese Corporate Bonds [Member]    
Assets:    
Financial assets required to be measured at FVPL 19,861 27,316
Financial assets designated to be measured at FVPL   3,302
Financial assets required to be measured at FVOCI 804,808 882,652
Recurring fair value measurement [member] | Debt securities [member] | Foreign Government Bonds [Member]    
Assets:    
Financial assets required to be measured at FVPL 221,213 231,688
Financial assets designated to be measured at FVPL 50,569 39,472
Financial assets required to be measured at FVOCI 1,315,058 1,221,208
Recurring fair value measurement [member] | Debt securities [member] | Foreign Corporate Bonds [Member]    
Assets:    
Financial assets required to be measured at FVPL 27,506 14,914
Financial assets designated to be measured at FVPL 77,450 165,081
Financial assets required to be measured at FVOCI 414,930 301,119
Recurring fair value measurement [member] | Debt securities [member] | Securitized Products [Member]    
Assets:    
Financial assets required to be measured at FVOCI 108,580 82,573
Recurring fair value measurement [member] | Debt securities [member] | Investment funds [member]    
Assets:    
Financial assets required to be measured at FVPL 733,525 619,372
Recurring fair value measurement [member] | Equity securities [member]    
Assets:    
Financial assets required to be measured at FVPL 4,227,643 3,469,235
Financial assets designated to be measured at FVOCI 388,827 317,015
Recurring fair value measurement [member] | Derivatives [member] | Interest rate swap contract [member]    
Assets:    
Financial assets required to be measured at FVPL 65,433 49,619
Recurring fair value measurement [member] | Derivatives [member] | Foreign Exchange Contracts [Member]    
Assets:    
Financial assets required to be measured at FVPL 15,255 20,425
Recurring fair value measurement [member] | Derivatives [member] | Equity Contracts [Member]    
Assets:    
Financial assets required to be measured at FVPL 4,167 2,379
Recurring fair value measurement [member] | Derivatives [member] | Bond Contracts [Member]    
Assets:    
Financial assets required to be measured at FVPL 1,286  
Investments And Advances In The Financial Services Segment Current [Member] | Recurring fair value measurement [member]    
Assets:    
Total assets 134,589 110,509
Investments And Advances In The Financial Services Segment Current [Member] | Recurring fair value measurement [member] | Debt securities [member] | Japanese National Government Bonds [Member]    
Assets:    
Financial assets designated to be measured at FVPL 3,494 4,302
Financial assets required to be measured at FVOCI 35,000 300
Investments And Advances In The Financial Services Segment Current [Member] | Recurring fair value measurement [member] | Debt securities [member] | Japanese local government bonds [Member]    
Assets:    
Financial assets designated to be measured at FVPL 8,596 5,310
Financial assets required to be measured at FVOCI 11,055 550
Investments And Advances In The Financial Services Segment Current [Member] | Recurring fair value measurement [member] | Debt securities [member] | Japanese Corporate Bonds [Member]    
Assets:    
Financial assets designated to be measured at FVPL   3,302
Financial assets required to be measured at FVOCI 11,087 11,414
Investments And Advances In The Financial Services Segment Current [Member] | Recurring fair value measurement [member] | Debt securities [member] | Foreign Government Bonds [Member]    
Assets:    
Financial assets designated to be measured at FVPL 5,639 7,390
Financial assets required to be measured at FVOCI 4,612  
Investments And Advances In The Financial Services Segment Current [Member] | Recurring fair value measurement [member] | Debt securities [member] | Foreign Corporate Bonds [Member]    
Assets:    
Financial assets designated to be measured at FVPL 25,659 49,578
Financial assets required to be measured at FVOCI 29,447 28,363
Other Financial Assets Current [Member] | Recurring fair value measurement [member]    
Assets:    
Total assets 19,767 22,162
Other Financial Assets Current [Member] | Recurring fair value measurement [member] | Derivatives [member] | Interest rate swap contract [member]    
Assets:    
Financial assets required to be measured at FVPL 493 1,009
Other Financial Assets Current [Member] | Recurring fair value measurement [member] | Derivatives [member] | Foreign Exchange Contracts [Member]    
Assets:    
Financial assets required to be measured at FVPL 13,821 18,774
Other Financial Assets Current [Member] | Recurring fair value measurement [member] | Derivatives [member] | Equity Contracts [Member]    
Assets:    
Financial assets required to be measured at FVPL 4,167 2,379
Other Financial Assets Current [Member] | Recurring fair value measurement [member] | Derivatives [member] | Bond Contracts [Member]    
Assets:    
Financial assets required to be measured at FVPL 1,286  
Investments And Advances In The Financial Services Segment Noncurrent [Member] | Recurring fair value measurement [member]    
Assets:    
Total assets 14,749,121 15,239,597
Investments And Advances In The Financial Services Segment Noncurrent [Member] | Recurring fair value measurement [member] | Debt securities [member] | Japanese National Government Bonds [Member]    
Assets:    
Financial assets required to be measured at FVPL 411,764 423,129
Financial assets designated to be measured at FVPL 753,863 1,017,007
Financial assets required to be measured at FVOCI 6,099,141 7,057,095
Investments And Advances In The Financial Services Segment Noncurrent [Member] | Recurring fair value measurement [member] | Debt securities [member] | Japanese local government bonds [Member]    
Assets:    
Financial assets required to be measured at FVPL 1,225 1,846
Financial assets designated to be measured at FVPL   8,635
Financial assets required to be measured at FVOCI 60,697 48,162
Investments And Advances In The Financial Services Segment Noncurrent [Member] | Recurring fair value measurement [member] | Debt securities [member] | Japanese Corporate Bonds [Member]    
Assets:    
Financial assets required to be measured at FVPL 19,828 27,296
Financial assets required to be measured at FVOCI 793,721 871,238
Investments And Advances In The Financial Services Segment Noncurrent [Member] | Recurring fair value measurement [member] | Debt securities [member] | Foreign Government Bonds [Member]    
Assets:    
Financial assets required to be measured at FVPL 221,213 231,688
Financial assets designated to be measured at FVPL 44,930 32,082
Financial assets required to be measured at FVOCI 1,310,307 1,221,068
Investments And Advances In The Financial Services Segment Noncurrent [Member] | Recurring fair value measurement [member] | Debt securities [member] | Foreign Corporate Bonds [Member]    
Assets:    
Financial assets required to be measured at FVPL 24,657 11,981
Financial assets designated to be measured at FVPL 51,791 115,503
Financial assets required to be measured at FVOCI 385,483 272,756
Investments And Advances In The Financial Services Segment Noncurrent [Member] | Recurring fair value measurement [member] | Debt securities [member] | Securitized Products [Member]    
Assets:    
Financial assets required to be measured at FVOCI 108,580 82,573
Investments And Advances In The Financial Services Segment Noncurrent [Member] | Recurring fair value measurement [member] | Debt securities [member] | Investment funds [member]    
Assets:    
Financial assets required to be measured at FVPL 715,852 599,937
Investments And Advances In The Financial Services Segment Noncurrent [Member] | Recurring fair value measurement [member] | Equity securities [member]    
Assets:    
Financial assets required to be measured at FVPL 3,740,189 3,210,296
Financial assets designated to be measured at FVOCI 5,880 7,305
Other Financial Assets Non Current [Member] | Recurring fair value measurement [member]    
Assets:    
Total assets 957,469 641,438
Other Financial Assets Non Current [Member] | Recurring fair value measurement [member] | Debt securities [member] | Japanese Corporate Bonds [Member]    
Assets:    
Financial assets required to be measured at FVPL 33 20
Other Financial Assets Non Current [Member] | Recurring fair value measurement [member] | Debt securities [member] | Foreign Government Bonds [Member]    
Assets:    
Financial assets required to be measured at FVOCI 139 140
Other Financial Assets Non Current [Member] | Recurring fair value measurement [member] | Debt securities [member] | Foreign Corporate Bonds [Member]    
Assets:    
Financial assets required to be measured at FVPL 2,849 2,933
Other Financial Assets Non Current [Member] | Recurring fair value measurement [member] | Debt securities [member] | Investment funds [member]    
Assets:    
Financial assets required to be measured at FVPL 17,673 19,435
Other Financial Assets Non Current [Member] | Recurring fair value measurement [member] | Equity securities [member]    
Assets:    
Financial assets required to be measured at FVPL 487,454 258,939
Financial assets designated to be measured at FVOCI 382,947 309,710
Other Financial Assets Non Current [Member] | Recurring fair value measurement [member] | Derivatives [member] | Interest rate swap contract [member]    
Assets:    
Financial assets required to be measured at FVPL 64,940 48,610
Other Financial Assets Non Current [Member] | Recurring fair value measurement [member] | Derivatives [member] | Foreign Exchange Contracts [Member]    
Assets:    
Financial assets required to be measured at FVPL 1,434 1,651
Other Financial Liabilities Current [Member] | Recurring fair value measurement [member]    
Liabilities:    
Total liabilities 43,607 48,240
Other Financial Liabilities Current [Member] | Recurring fair value measurement [member] | Contingent consideration [member]    
Liabilities:    
Financial liabilities required to be measured at FVPL 11,594 26,193
Other Financial Liabilities Current [Member] | Recurring fair value measurement [member] | Redeemable Non Controlling Interests [Member]    
Liabilities:    
Financial liabilities designated to be measured at FVPL 10,912  
Other Financial Liabilities Current [Member] | Recurring fair value measurement [member] | Interest rate swap contract [member] | Derivative Liabilities [Member]    
Liabilities:    
Financial liabilities required to be measured at FVPL 1,016 406
Other Financial Liabilities Current [Member] | Recurring fair value measurement [member] | Foreign Exchange Contracts [Member] | Derivative Liabilities [Member]    
Liabilities:    
Financial liabilities required to be measured at FVPL 15,778 16,297
Other Financial Liabilities Current [Member] | Recurring fair value measurement [member] | Equity Contracts [Member] | Derivative Liabilities [Member]    
Liabilities:    
Financial liabilities required to be measured at FVPL 514 5,344
Other Financial Liabilities Current [Member] | Recurring fair value measurement [member] | Bond Contracts [Member] | Derivative Liabilities [Member]    
Liabilities:    
Financial liabilities required to be measured at FVPL 3,793  
Other Financial Liabilities Non current [Member] | Recurring fair value measurement [member]    
Liabilities:    
Total liabilities 189,667 85,418
Other Financial Liabilities Non current [Member] | Recurring fair value measurement [member] | Contingent consideration [member]    
Liabilities:    
Financial liabilities required to be measured at FVPL 14,191 24,150
Other Financial Liabilities Non current [Member] | Recurring fair value measurement [member] | Redeemable Non Controlling Interests [Member]    
Liabilities:    
Financial liabilities designated to be measured at FVPL 42,051 54,028
Other Financial Liabilities Non current [Member] | Recurring fair value measurement [member] | Interest rate swap contract [member] | Derivative Liabilities [Member]    
Liabilities:    
Financial liabilities required to be measured at FVPL 14,819 6,044
Other Financial Liabilities Non current [Member] | Recurring fair value measurement [member] | Foreign Exchange Contracts [Member] | Derivative Liabilities [Member]    
Liabilities:    
Financial liabilities required to be measured at FVPL   1,196
Other Financial Liabilities Non current [Member] | Recurring fair value measurement [member] | Equity Contracts [Member] | Derivative Liabilities [Member]    
Liabilities:    
Financial liabilities required to be measured at FVPL 118,606  
Level 1 [Member] | Recurring fair value measurement [member]    
Assets:    
Total assets 4,341,247 3,558,852
Liabilities:    
Total liabilities 4,307 3,428
Level 1 [Member] | Recurring fair value measurement [member] | Equity Contracts [Member] | Derivative Liabilities [Member]    
Liabilities:    
Financial liabilities required to be measured at FVPL 514 3,428
Level 1 [Member] | Recurring fair value measurement [member] | Bond Contracts [Member] | Derivative Liabilities [Member]    
Liabilities:    
Financial liabilities required to be measured at FVPL 3,793  
Level 1 [Member] | Recurring fair value measurement [member] | Debt securities [member] | Foreign Government Bonds [Member]    
Assets:    
Financial assets required to be measured at FVPL 41,867 39,363
Level 1 [Member] | Recurring fair value measurement [member] | Equity securities [member]    
Assets:    
Financial assets required to be measured at FVPL 4,210,845 3,451,655
Financial assets designated to be measured at FVOCI 86,339 67,834
Level 1 [Member] | Recurring fair value measurement [member] | Derivatives [member] | Equity Contracts [Member]    
Assets:    
Financial assets required to be measured at FVPL 910  
Level 1 [Member] | Recurring fair value measurement [member] | Derivatives [member] | Bond Contracts [Member]    
Assets:    
Financial assets required to be measured at FVPL 1,286  
Level 2 [Member] | Recurring fair value measurement [member]    
Assets:    
Total assets 10,907,662 11,922,016
Liabilities:    
Total liabilities 31,613 25,859
Level 2 [Member] | Recurring fair value measurement [member] | Interest rate swap contract [member] | Derivative Liabilities [Member]    
Liabilities:    
Financial liabilities required to be measured at FVPL 15,835 6,450
Level 2 [Member] | Recurring fair value measurement [member] | Foreign Exchange Contracts [Member] | Derivative Liabilities [Member]    
Liabilities:    
Financial liabilities required to be measured at FVPL 15,778 17,493
Level 2 [Member] | Recurring fair value measurement [member] | Equity Contracts [Member] | Derivative Liabilities [Member]    
Liabilities:    
Financial liabilities required to be measured at FVPL   1,916
Level 2 [Member] | Recurring fair value measurement [member] | Debt securities [member] | Japanese National Government Bonds [Member]    
Assets:    
Financial assets required to be measured at FVPL 411,764 423,129
Financial assets designated to be measured at FVPL 757,357 1,021,309
Financial assets required to be measured at FVOCI 6,134,141 7,057,395
Level 2 [Member] | Recurring fair value measurement [member] | Debt securities [member] | Japanese local government bonds [Member]    
Assets:    
Financial assets required to be measured at FVPL 1,225 1,846
Financial assets designated to be measured at FVPL 8,596 13,945
Financial assets required to be measured at FVOCI 71,752 48,712
Level 2 [Member] | Recurring fair value measurement [member] | Debt securities [member] | Japanese Corporate Bonds [Member]    
Assets:    
Financial assets required to be measured at FVPL 19,828 27,296
Financial assets designated to be measured at FVPL   3,302
Financial assets required to be measured at FVOCI 693,016 743,804
Level 2 [Member] | Recurring fair value measurement [member] | Debt securities [member] | Foreign Government Bonds [Member]    
Assets:    
Financial assets required to be measured at FVPL 179,346 192,325
Financial assets designated to be measured at FVPL 50,569 39,472
Financial assets required to be measured at FVOCI 1,315,058 1,221,208
Level 2 [Member] | Recurring fair value measurement [member] | Debt securities [member] | Foreign Corporate Bonds [Member]    
Assets:    
Financial assets required to be measured at FVPL 24,657 11,981
Financial assets designated to be measured at FVPL 71,408 159,158
Financial assets required to be measured at FVOCI 353,862 266,362
Level 2 [Member] | Recurring fair value measurement [member] | Debt securities [member] | Securitized Products [Member]    
Assets:    
Financial assets required to be measured at FVOCI 59,702 60,565
Level 2 [Member] | Recurring fair value measurement [member] | Debt securities [member] | Investment funds [member]    
Assets:    
Financial assets required to be measured at FVPL 666,662 552,017
Level 2 [Member] | Recurring fair value measurement [member] | Equity securities [member]    
Assets:    
Financial assets required to be measured at FVPL 7,120 8,146
Level 2 [Member] | Recurring fair value measurement [member] | Derivatives [member] | Interest rate swap contract [member]    
Assets:    
Financial assets required to be measured at FVPL 65,433 49,619
Level 2 [Member] | Recurring fair value measurement [member] | Derivatives [member] | Foreign Exchange Contracts [Member]    
Assets:    
Financial assets required to be measured at FVPL 15,255 20,425
Level 2 [Member] | Recurring fair value measurement [member] | Derivatives [member] | Equity Contracts [Member]    
Assets:    
Financial assets required to be measured at FVPL 911  
Level 3 [Member] | Recurring fair value measurement [member]    
Assets:    
Total assets 612,037 532,838
Liabilities:    
Total liabilities 197,354 104,371
Level 3 [Member] | Recurring fair value measurement [member] | Contingent consideration [member]    
Liabilities:    
Financial liabilities required to be measured at FVPL 25,785 50,343
Level 3 [Member] | Recurring fair value measurement [member] | Redeemable Non Controlling Interests [Member]    
Liabilities:    
Financial liabilities designated to be measured at FVPL 52,963 54,028
Level 3 [Member] | Recurring fair value measurement [member] | Equity Contracts [Member] | Derivative Liabilities [Member]    
Liabilities:    
Financial liabilities required to be measured at FVPL 118,606  
Level 3 [Member] | Recurring fair value measurement [member] | Debt securities [member] | Japanese Corporate Bonds [Member]    
Assets:    
Financial assets required to be measured at FVPL 33 20
Financial assets required to be measured at FVOCI 111,792 138,848
Level 3 [Member] | Recurring fair value measurement [member] | Debt securities [member] | Foreign Corporate Bonds [Member]    
Assets:    
Financial assets required to be measured at FVPL 2,849 2,933
Financial assets designated to be measured at FVPL 6,042 5,923
Financial assets required to be measured at FVOCI 61,068 34,757
Level 3 [Member] | Recurring fair value measurement [member] | Debt securities [member] | Securitized Products [Member]    
Assets:    
Financial assets required to be measured at FVOCI 48,878 22,008
Level 3 [Member] | Recurring fair value measurement [member] | Debt securities [member] | Investment funds [member]    
Assets:    
Financial assets required to be measured at FVPL 66,863 67,355
Level 3 [Member] | Recurring fair value measurement [member] | Equity securities [member]    
Assets:    
Financial assets required to be measured at FVPL 9,678 9,434
Financial assets designated to be measured at FVOCI 302,488 249,181
Level 3 [Member] | Recurring fair value measurement [member] | Derivatives [member] | Equity Contracts [Member]    
Assets:    
Financial assets required to be measured at FVPL ¥ 2,346 ¥ 2,379