v3.26.1
Other Assets and Liabilities (Summarized Financial Information of Equity Method Investees, Other than Morgan Stanley) (Detail) - JPY (¥)
¥ in Millions
 12 Months Ended
Mar. 31, 2026
Mar. 31, 2025
Mar. 31, 2024
Schedule of Equity Method Investments [Line Items]      
Total assets ¥ 425,581,652 ¥ 405,940,211 ¥ 397,820,570
Total liabilities 404,741,595 386,690,473  
Noncontrolling interests 1,266,924 964,252  
Equity Method Investment, Summarized Financial Information, Income and Loss      
Net income applicable to Morgan Stanley 1,883,904 1,267,638 1,377,569
Equity Method Investees Other than Morgan Stanley      
Schedule of Equity Method Investments [Line Items]      
Net loans 21,992,000 20,315,000  
Total assets 44,782,000 40,852,000  
Deposits 15,644,000 13,742,000  
Total liabilities 35,404,000 32,900,000  
Noncontrolling interests 106,000 93,000  
Equity Method Investment, Summarized Financial Information, Income and Loss      
Total interest income 2,052,000 1,998,000 1,820,000
Total interest expense 868,000 775,000 782,000
Net interest income 1,184,000 1,223,000 1,038,000
Provision for credit losses 252,000 366,000 291,000
Income before income tax expense 1,164,000 838,000 698,000
Net income applicable to Morgan Stanley ¥ 997,000 ¥ 704,000 ¥ 596,000