v3.26.1
Business Segments (Narrative) (Detail)
¥ in Billions
12 Months Ended
Mar. 31, 2026
segment
Mar. 31, 2025
JPY (¥)
Mar. 31, 2024
JPY (¥)
Segment Reporting Information [Line Items]      
Number of operating segments | segment 7    
Number of reportable segments | segment 7    
Operating Segments | Retail & Digital Business Group | Customer business | Revision of prior period, reclassification, adjustment      
Segment Reporting Information [Line Items]      
Modification impact in operating profits (losses)   ¥ 1.1 ¥ 1.7
Operating Segments | Commercial Banking & Wealth Management Business Group | Customer business | Revision of prior period, reclassification, adjustment      
Segment Reporting Information [Line Items]      
Modification impact in operating profits (losses)   1.1 0.5
Operating Segments | Global Markets Business Group | Customer business | Revision of prior period, reclassification, adjustment      
Segment Reporting Information [Line Items]      
Modification impact in operating profits (losses)   (9.1) (8.5)
Operating Segments | Global Corporate & Investment Banking Business Group | Customer business | Revision of prior period, reclassification, adjustment      
Segment Reporting Information [Line Items]      
Modification impact in operating profits (losses)   (12.2) (6.8)
Operating Segments | Japanese Corporate & Investment Banking Business Group | Customer business | Revision of prior period, reclassification, adjustment      
Segment Reporting Information [Line Items]      
Modification impact in operating profits (losses)   (2.4) (2.7)
Operating Segments | Global Commercial Banking Business Group | Customer business | Revision of prior period, reclassification, adjustment      
Segment Reporting Information [Line Items]      
Modification impact in operating profits (losses)   (0.1) (0.1)
Other | Revision of prior period, reclassification, adjustment      
Segment Reporting Information [Line Items]      
Modification impact in operating profits (losses)   ¥ 21.6 ¥ 15.9