v3.26.1
Severance Indemnities and Pension Plans (Combined Funded Status and Amounts Recognized in Consolidated Balance Sheets) (Detail) - JPY (¥)
¥ in Millions
 12 Months Ended
Mar. 31, 2026
Mar. 31, 2025
Mar. 31, 2024
Amounts recognized in the consolidated balance sheets:      
Prepaid benefit cost ¥ 2,639,445 ¥ 2,196,632  
Accrued benefit cost (106,363) (103,957)  
Domestic, Japan | Non-contributory pension benefits and SIP      
Change in benefit obligation:      
Benefit obligation at beginning of fiscal year 1,310,512 1,448,579  
Service cost 28,099 31,728  
Interest cost 30,210 23,954  
Plan participants’ contributions 0 0  
Acquisitions/ Divestitures (257) (354)  
Amendments 0 0  
Actuarial loss (gain) (97,490) (109,527)  
Benefits paid (66,015) (65,960)  
Lump-sum payment (13,495) (17,908)  
Translation adjustments and other 0 0  
Benefit obligation at end of fiscal year 1,191,564 1,310,512 ¥ 1,448,579
Change in plan assets:      
Fair value of plan assets at beginning of fiscal year 3,409,772 3,333,330  
Actual return on plan assets 358,683 117,384  
Employer contributions 25,130 25,184  
Acquisitions/ Divestitures (182) (26)  
Plan participants’ contributions 0 0  
Benefits paid (66,015) (65,960)  
Translation adjustments and other 0 (140)  
Fair value of plan assets at end of fiscal year 3,727,388 3,409,772 3,333,330
Amounts recognized in the consolidated balance sheets:      
Prepaid benefit cost 2,553,516 2,116,823  
Accrued benefit cost (17,691) (17,563)  
Net amount recognized 2,535,825 2,099,260  
Foreign offices and subsidiaries | Pension benefits      
Change in benefit obligation:      
Benefit obligation at beginning of fiscal year 199,316 198,793  
Service cost 13,354 14,759 13,231
Interest cost 9,303 8,850 8,461
Plan participants’ contributions 0 0  
Acquisitions/ Divestitures 1,478 0  
Amendments 0 (2,075)  
Actuarial loss (gain) 2,757 (5,195)  
Benefits paid (9,139) (7,721)  
Lump-sum payment (6,568) (5,837)  
Translation adjustments and other 9,946 (2,258)  
Benefit obligation at end of fiscal year 220,447 199,316 198,793
Change in plan assets:      
Fair value of plan assets at beginning of fiscal year 193,635 196,991  
Actual return on plan assets 13,285 7,761  
Employer contributions 4,653 2,826  
Acquisitions/ Divestitures 0 0  
Plan participants’ contributions 0 0  
Benefits paid (9,139) (7,721)  
Translation adjustments and other 14,528 (6,222)  
Fair value of plan assets at end of fiscal year 216,962 193,635 196,991
Amounts recognized in the consolidated balance sheets:      
Prepaid benefit cost 84,712 79,809  
Accrued benefit cost (88,197) (85,490)  
Net amount recognized (3,485) (5,681)  
Foreign offices and subsidiaries | Other benefits      
Change in benefit obligation:      
Benefit obligation at beginning of fiscal year 23,394 25,719  
Service cost 77 52 52
Interest cost 1,144 1,266 1,216
Plan participants’ contributions 362 430  
Acquisitions/ Divestitures 0 0  
Amendments 0 0  
Actuarial loss (gain) (573) (1,107)  
Benefits paid (2,439) (2,555)  
Translation adjustments and other 1,434 (411)  
Benefit obligation at end of fiscal year 23,399 23,394 25,719
Change in plan assets:      
Fair value of plan assets at beginning of fiscal year 22,490 23,671  
Actual return on plan assets 1,911 993  
Acquisitions/ Divestitures 0 0  
Plan participants’ contributions 362 430  
Benefits paid (2,439) (2,555)  
Translation adjustments and other 1,563 (277)  
Fair value of plan assets at end of fiscal year 24,141 22,490 ¥ 23,671
Amounts recognized in the consolidated balance sheets:      
Prepaid benefit cost 1,217 0  
Accrued benefit cost (475) (904)  
Net amount recognized 742 (904)  
Foreign offices and subsidiaries | Other benefits netting      
Change in plan assets:      
Employer contributions ¥ 254 ¥ 228