v3.26.1
Financial instruments - Summary of Assets and Liabilities that are Measured at Fair Value on a Recurring Basis (Detail) - JPY (¥)
¥ in Millions
Mar. 31, 2026
Mar. 31, 2025
Derivative Liabilities [Member]    
Liabilities:    
Financial liabilities required to be measured at FVPL ¥ 70,216 ¥ 154,526
Contingent consideration [member]    
Liabilities:    
Financial liabilities required to be measured at FVPL 16,549 25,785
Redeemable Non Controlling Interests [Member]    
Liabilities:    
Financial liabilities designated to be measured at FVPL 78,568 52,963
Recurring fair value measurement [member]    
Assets:    
Total assets 989,526 15,860,946
Liabilities:    
Total liabilities 165,333 233,274
Recurring fair value measurement [member] | Contingent consideration [member]    
Liabilities:    
Financial liabilities required to be measured at FVPL 16,549 25,785
Recurring fair value measurement [member] | Redeemable Non Controlling Interests [Member]    
Liabilities:    
Financial liabilities designated to be measured at FVPL 78,568 52,963
Recurring fair value measurement [member] | Interest rate swap contract [member] | Derivative Liabilities [Member]    
Liabilities:    
Financial liabilities required to be measured at FVPL   15,835
Recurring fair value measurement [member] | Foreign Exchange Contracts [Member] | Derivative Liabilities [Member]    
Liabilities:    
Financial liabilities required to be measured at FVPL 14,553 15,778
Recurring fair value measurement [member] | Equity Contracts [Member] | Derivative Liabilities [Member]    
Liabilities:    
Financial liabilities required to be measured at FVPL 55,663 119,120
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
Financial assets designated to be measured at FVPL   757,357
Financial assets required to be measured at FVOCI   6,134,141
Recurring fair value measurement [member] | Debt securities [member] | Japanese local government bonds [Member]    
Assets:    
Financial assets required to be measured at FVPL   1,225
Financial assets designated to be measured at FVPL   8,596
Financial assets required to be measured at FVOCI   71,752
Recurring fair value measurement [member] | Debt securities [member] | Japanese Corporate Bonds [Member]    
Assets:    
Financial assets required to be measured at FVPL 170 19,861
Financial assets required to be measured at FVOCI   804,808
Recurring fair value measurement [member] | Debt securities [member] | Foreign Government Bonds [Member]    
Assets:    
Financial assets required to be measured at FVPL   221,213
Financial assets designated to be measured at FVPL   50,569
Financial assets required to be measured at FVOCI 158 1,315,058
Recurring fair value measurement [member] | Debt securities [member] | Foreign Corporate Bonds [Member]    
Assets:    
Financial assets required to be measured at FVPL 6,601 27,506
Financial assets designated to be measured at FVPL   77,450
Financial assets required to be measured at FVOCI   414,930
Recurring fair value measurement [member] | Debt securities [member] | Securitized Products [Member]    
Assets:    
Financial assets required to be measured at FVOCI   108,580
Recurring fair value measurement [member] | Debt securities [member] | Investment funds [member]    
Assets:    
Financial assets required to be measured at FVPL 16,646 733,525
Recurring fair value measurement [member] | Equity securities [member]    
Assets:    
Financial assets required to be measured at FVPL 470,508 4,227,643
Financial assets designated to be measured at FVOCI 467,489 388,827
Recurring fair value measurement [member] | Derivatives [member] | Interest rate swap contract [member]    
Assets:    
Financial assets required to be measured at FVPL 20,982 65,433
Recurring fair value measurement [member] | Derivatives [member] | Foreign Exchange Contracts [Member]    
Assets:    
Financial assets required to be measured at FVPL 6,972 15,255
Recurring fair value measurement [member] | Derivatives [member] | Equity Contracts [Member]    
Assets:    
Financial assets required to be measured at FVPL   4,167
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
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
Financial assets required to be measured at FVOCI   35,000
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
Financial assets required to be measured at FVOCI   11,055
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 required to be measured at FVOCI   11,087
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
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
Financial assets required to be measured at FVOCI   29,447
Other Financial Assets Current [Member] | Recurring fair value measurement [member]    
Assets:    
Total assets 6,972 19,767
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
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 6,972 13,821
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
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
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
Financial assets designated to be measured at FVPL   753,863
Financial assets required to be measured at FVOCI   6,099,141
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
Financial assets designated to be measured at FVPL   0
Financial assets required to be measured at FVOCI   60,697
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
Financial assets required to be measured at FVOCI   793,721
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
Financial assets designated to be measured at FVPL   44,930
Financial assets required to be measured at FVOCI   1,310,307
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
Financial assets designated to be measured at FVPL   51,791
Financial assets required to be measured at FVOCI   385,483
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
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
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
Financial assets designated to be measured at FVOCI   5,880
Other Financial Assets Non Current [Member] | Recurring fair value measurement [member]    
Assets:    
Total assets 982,554 957,469
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 170 33
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 158 139
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 6,601 2,849
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 16,646 17,673
Other Financial Assets Non Current [Member] | Recurring fair value measurement [member] | Equity securities [member]    
Assets:    
Financial assets required to be measured at FVPL 470,508 487,454
Financial assets designated to be measured at FVOCI 467,489 382,947
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 20,982 64,940
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
Other Financial Liabilities Current [Member] | Recurring fair value measurement [member]    
Liabilities:    
Total liabilities 115,785 43,607
Other Financial Liabilities Current [Member] | Recurring fair value measurement [member] | Contingent consideration [member]    
Liabilities:    
Financial liabilities required to be measured at FVPL 9,906 11,594
Other Financial Liabilities Current [Member] | Recurring fair value measurement [member] | Redeemable Non Controlling Interests [Member]    
Liabilities:    
Financial liabilities designated to be measured at FVPL 35,663 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
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 14,553 15,778
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 55,663 514
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 49,548 189,667
Other Financial Liabilities Non current [Member] | Recurring fair value measurement [member] | Contingent consideration [member]    
Liabilities:    
Financial liabilities required to be measured at FVPL 6,643 14,191
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 42,905 42,051
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
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   0
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 0 118,606
Level 1 [Member] | Recurring fair value measurement [member]    
Assets:    
Total assets 595,469 4,341,247
Liabilities:    
Total liabilities 0 4,307
Level 1 [Member] | Recurring fair value measurement [member] | Equity Contracts [Member] | Derivative Liabilities [Member]    
Liabilities:    
Financial liabilities required to be measured at FVPL 0 514
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
Level 1 [Member] | Recurring fair value measurement [member] | Equity securities [member]    
Assets:    
Financial assets required to be measured at FVPL 446,932 4,210,845
Financial assets designated to be measured at FVOCI 148,537 86,339
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 36,659 10,907,662
Liabilities:    
Total liabilities 14,553 31,613
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
Level 2 [Member] | Recurring fair value measurement [member] | Foreign Exchange Contracts [Member] | Derivative Liabilities [Member]    
Liabilities:    
Financial liabilities required to be measured at FVPL 14,553 15,778
Level 2 [Member] | Recurring fair value measurement [member] | Equity Contracts [Member] | Derivative Liabilities [Member]    
Liabilities:    
Financial liabilities required to be measured at FVPL   0
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
Financial assets designated to be measured at FVPL   757,357
Financial assets required to be measured at FVOCI   6,134,141
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
Financial assets designated to be measured at FVPL   8,596
Financial assets required to be measured at FVOCI   71,752
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
Financial assets required to be measured at FVOCI   693,016
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
Financial assets designated to be measured at FVPL   50,569
Financial assets required to be measured at FVOCI 158 1,315,058
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
Financial assets designated to be measured at FVPL   71,408
Financial assets required to be measured at FVOCI   353,862
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
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
Level 2 [Member] | Recurring fair value measurement [member] | Equity securities [member]    
Assets:    
Financial assets required to be measured at FVPL 8,547 7,120
Level 2 [Member] | Recurring fair value measurement [member] | Derivatives [member] | Interest rate swap contract [member]    
Assets:    
Financial assets required to be measured at FVPL 20,982 65,433
Level 2 [Member] | Recurring fair value measurement [member] | Derivatives [member] | Foreign Exchange Contracts [Member]    
Assets:    
Financial assets required to be measured at FVPL 6,972 15,255
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 357,398 612,037
Liabilities:    
Total liabilities 150,780 197,354
Level 3 [Member] | Recurring fair value measurement [member] | Contingent consideration [member]    
Liabilities:    
Financial liabilities required to be measured at FVPL 16,549 25,785
Level 3 [Member] | Recurring fair value measurement [member] | Redeemable Non Controlling Interests [Member]    
Liabilities:    
Financial liabilities designated to be measured at FVPL 78,568 52,963
Level 3 [Member] | Recurring fair value measurement [member] | Equity Contracts [Member] | Derivative Liabilities [Member]    
Liabilities:    
Financial liabilities required to be measured at FVPL 55,663 118,606
Level 3 [Member] | Recurring fair value measurement [member] | Debt securities [member] | Japanese Corporate Bonds [Member]    
Assets:    
Financial assets required to be measured at FVPL 170 33
Financial assets required to be measured at FVOCI   111,792
Level 3 [Member] | Recurring fair value measurement [member] | Debt securities [member] | Foreign Corporate Bonds [Member]    
Assets:    
Financial assets required to be measured at FVPL 6,601 2,849
Financial assets designated to be measured at FVPL   6,042
Financial assets required to be measured at FVOCI   61,068
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
Level 3 [Member] | Recurring fair value measurement [member] | Debt securities [member] | Investment funds [member]    
Assets:    
Financial assets required to be measured at FVPL 16,646 66,863
Level 3 [Member] | Recurring fair value measurement [member] | Equity securities [member]    
Assets:    
Financial assets required to be measured at FVPL 15,029 9,678
Financial assets designated to be measured at FVOCI ¥ 318,952 302,488
Level 3 [Member] | Recurring fair value measurement [member] | Derivatives [member] | Equity Contracts [Member]    
Assets:    
Financial assets required to be measured at FVPL   ¥ 2,346