v3.26.1
Intangible Assets - Summary of Changes in Cost, Accumulated Amortization and Impairment Losses of Intangible Assets (Detail) - JPY (¥)
¥ in Millions
 12 Months Ended
Mar. 31, 2026
Mar. 31, 2025
Statements [Line Items]    
Opening Balance ¥ 1,363,266  
Closing Balance 1,392,755 ¥ 1,363,266
Capitalized development costs [Member]    
Statements [Line Items]    
Opening Balance 582,606  
Closing Balance 523,437 582,606
Gross carrying amount [Member]    
Statements [Line Items]    
Opening Balance 2,270,435 2,198,228
Additions 102,039 60,914
Internally developed 322,812 300,775
Sales or disposal (298,378) (257,018)
Foreign currency translation adjustments 35,631 (5,414)
Other (59,730) (27,050)
Closing Balance 2,372,808 2,270,435
Gross carrying amount [Member] | Capitalized development costs [Member]    
Statements [Line Items]    
Opening Balance 1,066,981 1,058,334
Additions 0 0
Internally developed 106,751 111,546
Sales or disposal (149,833) (98,495)
Foreign currency translation adjustments 3,093 (564)
Other (40,490) (3,839)
Closing Balance 986,503 1,066,981
Gross carrying amount [Member] | Software and other [Member]    
Statements [Line Items]    
Opening Balance 1,203,454 1,139,895
Additions 102,039 60,914
Internally developed 216,060 189,229
Sales or disposal (148,545) (158,523)
Foreign currency translation adjustments 32,538 (4,850)
Other (19,240) (23,210)
Closing Balance 1,386,306 1,203,454
Accumulated depreciation, amortization [Member]    
Statements [Line Items]    
Opening Balance (907,169) (842,902)
Amortization (329,643) (307,700)
Sales or disposal 249,100 242,919
Foreign currency translation adjustments (17,198) 2,577
Other 24,857 (2,062)
Closing Balance (980,053) (907,169)
Accumulated depreciation, amortization [Member] | Capitalized development costs [Member]    
Statements [Line Items]    
Opening Balance (484,375) (419,997)
Amortization (151,780) (162,068)
Sales or disposal 149,833 98,495
Foreign currency translation adjustments 0 0
Other 23,257 805
Closing Balance (463,066) (484,375)
Accumulated depreciation, amortization [Member] | Software and other [Member]    
Statements [Line Items]    
Opening Balance (422,794) (422,905)
Amortization (177,862) (145,632)
Sales or disposal 99,267 144,423
Foreign currency translation adjustments (17,198) 2,577
Other 1,600 (1,257)
Closing Balance ¥ (516,987) ¥ (422,794)