v3.25.2
Other Assets and Liabilities (Summarized Financial Information of Morgan Stanley) (Detail) - JPY (¥)
¥ in Millions
 12 Months Ended
Mar. 31, 2025
Mar. 31, 2024
Mar. 31, 2023
Schedule of Equity Method Investments [Line Items]      
Total assets ¥ 405,940,211 ¥ 397,820,570 ¥ 382,177,876
Total liabilities 386,690,473 379,303,483  
Noncontrolling interests 964,252 841,350  
Equity Method Investment, Summarized Financial Information, Income and Loss      
Net income applicable to Morgan Stanley 1,267,638 1,377,569 414,561
Morgan Stanley      
Schedule of Equity Method Investments [Line Items]      
Trading assets 59,844,000 55,663,000  
Securities purchased under agreements to resell 17,800,000 18,583,000  
Securities borrowed 20,967,000 20,115,000  
Total assets 194,420,000 186,008,000  
Deposits 57,051,000 53,371,000  
Customer and other payables 30,163,000 32,458,000  
Borrowings 45,662,000 41,090,000  
Total liabilities 178,295,000 170,845,000  
Noncontrolling interests 155,000 143,000  
Equity Method Investment, Summarized Financial Information, Income and Loss      
Net revenues 9,739,000 7,907,000 7,235,000
Total non-interest expenses 6,843,000 6,068,000 5,376,000
Income from continuing operations before income taxes 2,835,000 1,798,000 1,797,000
Net income applicable to Morgan Stanley ¥ 2,162,000 ¥ 1,375,000 ¥ 1,402,000