v3.25.2
Segment Information - Summary of Revenues from External Customers (Detail) - JPY (¥)
¥ in Millions
 12 Months Ended
Mar. 31, 2025
Mar. 31, 2024
Mar. 31, 2023
Disclosure of revenues from external customers [Line Items]      
Revenue ¥ 48,036,704 ¥ 45,095,325 ¥ 37,154,298
Location of external customers [Member]      
Disclosure of revenues from external customers [Line Items]      
Revenue 48,036,704 45,095,325 37,154,298
Japan [Member]      
Disclosure of revenues from external customers [Line Items]      
Revenue 21,859,094 21,020,721 17,583,196
Japan [Member] | Location of external customers [Member]      
Disclosure of revenues from external customers [Line Items]      
Revenue 7,723,171 7,399,192 6,742,304
North America [Member]      
Disclosure of revenues from external customers [Line Items]      
Revenue 19,300,327 17,943,072 13,843,901
North America [Member] | Location of external customers [Member]      
Disclosure of revenues from external customers [Line Items]      
Revenue 18,985,399 17,694,375 13,578,084
Europe [Member]      
Disclosure of revenues from external customers [Line Items]      
Revenue 6,313,489 5,681,764 4,273,735
Europe [Member] | Location of external customers [Member]      
Disclosure of revenues from external customers [Line Items]      
Revenue 5,979,720 5,396,610 3,970,857
Asia [Member]      
Disclosure of revenues from external customers [Line Items]      
Revenue 8,988,062 8,730,749 8,044,906
Asia [Member] | Location of external customers [Member]      
Disclosure of revenues from external customers [Line Items]      
Revenue 7,944,206 7,742,141 7,150,555
Other [Member]      
Disclosure of revenues from external customers [Line Items]      
Revenue 4,521,257 4,389,785 3,472,193
Other [Member] | Location of external customers [Member]      
Disclosure of revenues from external customers [Line Items]      
Revenue ¥ 7,404,208 ¥ 6,863,007 ¥ 5,712,497