v3.26.1
Segment Information - Summary of Geographical Information (Detail) - JPY (¥)
¥ in Millions
 12 Months Ended
Mar. 31, 2026
Mar. 31, 2025
Mar. 31, 2024
Disclosure of geographical areas [line items]      
Sales revenues ¥ 50,684,952 ¥ 48,036,704 ¥ 45,095,325
Non-current assets 19,788,499 17,704,029 16,486,260
Revenues from external customers [Member]      
Disclosure of geographical areas [line items]      
Sales revenues 50,684,952 48,036,704 45,095,325
Japan [Member]      
Disclosure of geographical areas [line items]      
Non-current assets 6,525,712 6,246,879 5,827,404
Japan [Member] | Revenues from external customers [Member]      
Disclosure of geographical areas [line items]      
Sales revenues 10,985,614 10,719,120 10,193,556
United States [Member]      
Disclosure of geographical areas [line items]      
Non-current assets 8,388,696 7,242,318 6,679,478
United States [Member] | Revenues from external customers [Member]      
Disclosure of geographical areas [line items]      
Sales revenues 18,493,969 16,981,710 15,784,361
Other [Member]      
Disclosure of geographical areas [line items]      
Non-current assets 4,874,091 4,214,833 3,979,378
Other [Member] | Revenues from external customers [Member]      
Disclosure of geographical areas [line items]      
Sales revenues ¥ 21,205,369 ¥ 20,335,874 ¥ 19,117,407