v3.26.1
Loans and Allowance for Credit Losses (Changes in Allowance for Credit Losses by Portfolio Segment) (Detail) - JPY (¥)
¥ in Millions
 12 Months Ended
Mar. 31, 2026
Mar. 31, 2025
Mar. 31, 2024
Financing Receivable, Allowance for Credit Losses [Line Items]      
Balance at beginning of fiscal year ¥ 1,243,075 ¥ 1,356,961 ¥ 1,279,514
Provision for credit losses (Note 4) 226,112 121,790 258,795
Charge-offs 361,055 337,151 314,375
Recoveries collected 64,541 70,892 65,236
Net charge-offs 296,514 266,259 249,139
Other 61,667 30,583 67,791
Balance at end of fiscal year 1,234,340 1,243,075 1,356,961
Allowance for credit losses at acquisition 14,067    
Effect of adopting new guidance on troubled debt restructurings and vintage disclosures      
Financing Receivable, Allowance for Credit Losses [Line Items]      
Other     18,869
Commercial      
Financing Receivable, Allowance for Credit Losses [Line Items]      
Balance at beginning of fiscal year 611,622 745,514 719,589
Provision for credit losses (Note 4) 24,661 (93,052) 66,240
Charge-offs 84,151 55,914 72,792
Recoveries collected 7,294 13,213 14,488
Net charge-offs 76,857 42,701 58,304
Other 8,173 1,861 17,989
Balance at end of fiscal year 567,599 611,622 745,514
Residential      
Financing Receivable, Allowance for Credit Losses [Line Items]      
Balance at beginning of fiscal year 49,607 56,964 59,747
Provision for credit losses (Note 4) (15,826) (6,729) (1,500)
Charge-offs 1,005 635 1,289
Recoveries collected 0 7 6
Net charge-offs 1,005 628 1,283
Other 0 0 0
Balance at end of fiscal year 32,776 49,607 56,964
Card      
Financing Receivable, Allowance for Credit Losses [Line Items]      
Balance at beginning of fiscal year 40,927 36,423 42,469
Provision for credit losses (Note 4) 30,027 25,607 21,927
Charge-offs 25,576 22,002 21,020
Recoveries collected 643 899 713
Net charge-offs 24,933 21,103 20,307
Other 0 0 (7,666)
Balance at end of fiscal year 46,021 40,927 36,423
Krungsri      
Financing Receivable, Allowance for Credit Losses [Line Items]      
Balance at beginning of fiscal year 423,857 405,211 364,647
Provision for credit losses (Note 4) 150,212 156,582 138,358
Charge-offs 198,727 199,643 180,641
Recoveries collected 44,067 40,340 32,856
Net charge-offs 154,660 159,303 147,785
Other 57,820 21,367 49,991
Balance at end of fiscal year 477,229 423,857 405,211
Allowance for credit losses at acquisition 14,067   20,134
Other      
Financing Receivable, Allowance for Credit Losses [Line Items]      
Balance at beginning of fiscal year 117,062 112,849 93,062
Provision for credit losses (Note 4) 37,038 39,382 33,770
Charge-offs 51,596 58,957 38,633
Recoveries collected 12,537 16,433 17,173
Net charge-offs 39,059 42,524 21,460
Other (4,326) 7,355 7,477
Balance at end of fiscal year ¥ 110,715 ¥ 117,062 112,849
Allowance for credit losses at acquisition     ¥ 2,097