v3.25.2
Intangible Assets - Summary of Changes in Cost, Accumulated Amortization and Impairment Losses of Intangible Assets (Detail) - JPY (¥)
¥ in Millions
 12 Months Ended
Mar. 31, 2025
Mar. 31, 2024
Statements [Line Items]    
Opening Balance ¥ 1,355,326  
Closing Balance 1,363,266 ¥ 1,355,326
Capitalized development costs [Member]    
Statements [Line Items]    
Opening Balance 638,337  
Closing Balance 582,606 638,337
Gross carrying amount [Member]    
Statements [Line Items]    
Opening Balance 2,198,228 2,124,830
Additions 60,914 109,051
Internally developed 300,775 260,895
Sales or disposal (257,018) (363,989)
Foreign currency translation adjustments (5,414) 46,726
Other (27,050) 20,715
Closing Balance 2,270,435 2,198,228
Gross carrying amount [Member] | Capitalized development costs [Member]    
Statements [Line Items]    
Opening Balance 1,058,334 1,159,435
Additions 0 0
Internally developed 111,546 124,788
Sales or disposal (98,495) (230,512)
Foreign currency translation adjustments (564) 4,622
Other (3,839) 0
Closing Balance 1,066,981 1,058,334
Gross carrying amount [Member] | Software and other [Member]    
Statements [Line Items]    
Opening Balance 1,139,895 965,395
Additions 60,914 109,051
Internally developed 189,229 136,107
Sales or disposal (158,523) (133,477)
Foreign currency translation adjustments (4,850) 42,104
Other (23,210) 20,715
Closing Balance 1,203,454 1,139,895
Accumulated depreciation, amortization [Member]    
Statements [Line Items]    
Opening Balance (842,902) (875,708)
Amortization (307,700) (290,642)
Sales or disposal 242,919 348,353
Foreign currency translation adjustments 2,577 (22,633)
Other (2,062) (2,272)
Closing Balance (907,169) (842,902)
Accumulated depreciation, amortization [Member] | Capitalized development costs [Member]    
Statements [Line Items]    
Opening Balance (419,997) (489,823)
Amortization (162,068) (160,686)
Sales or disposal 98,495 230,512
Foreign currency translation adjustments 0 0
Other (805) 0
Closing Balance (484,375) (419,997)
Accumulated depreciation, amortization [Member] | Software and other [Member]    
Statements [Line Items]    
Opening Balance (422,905) (385,886)
Amortization (145,632) (129,956)
Sales or disposal 144,423 117,841
Foreign currency translation adjustments 2,577 (22,633)
Other (1,257) (2,272)
Closing Balance ¥ (422,794) ¥ (422,905)