Regulatory Matters (Capital Requirements and Regulatory Adjustments Over Transitional Period) (Parenthetical) (Detail) |
12 Months Ended |
|---|---|
Mar. 31, 2026 | |
| After March 2026 | |
| Japan Gaap Schedule Of Compliance With Regulatory Capital Requirements Under Banking Regulations [Line Items] | |
| Countercyclical capital buffer | 0.13% |
| March 2028 | |
| Japan Gaap Schedule Of Compliance With Regulatory Capital Requirements Under Banking Regulations [Line Items] | |
| Additional loss absorbency requirements for G-SIBs and D-SIBs | 1.00% |
| March 2026 | |
| Japan Gaap Schedule Of Compliance With Regulatory Capital Requirements Under Banking Regulations [Line Items] | |
| Countercyclical capital buffer | 0.13% |
| Additional loss absorbency requirements for G-SIBs and D-SIBs | 1.00% |
| March 2026 | Basel III | |
| Japan Gaap Schedule Of Compliance With Regulatory Capital Requirements Under Banking Regulations [Line Items] | |
| Leverage ratio buffer | 50.00% |