v3.26.1
Investments in Associates and Joint Ventures - Summary of Investments in Associates and Joint Ventures (Detail)
12 Months Ended
Mar. 31, 2026
Sumitomo Mitsui Finance and Leasing Company, Limited [member]  
Disclosure of significant investments in associates and joint ventures [line items]  
Principal Joint Venture, Country of Incorporation Japan
Principal Joint Venture, Proportion of Ownership Interest 50.00% [1]
Principal Joint Venture, Proportion of Voting Rights 50.00% [1]
Principal Joint Venture, Main Business Leasing
PayPay Bank Corporation [member]  
Disclosure of significant investments in associates and joint ventures [line items]  
Principal Associates, Country of Incorporation Japan
Principal Associates, Proportion of Ownership Interest 21.50% [1]
Principal Associates, Proportion of Voting Rights 21.50% [1]
Principal Associates, Main Business Internet banking
YES BANK LIMITED [Member]  
Disclosure of significant investments in associates and joint ventures [line items]  
Principal Associates, Country of Incorporation India
Principal Associates, Proportion of Ownership Interest 24.90% [1]
Principal Associates, Proportion of Voting Rights 24.90% [1]
Principal Associates, Main Business Commercial banking
ACLEDA Bank Plc. [member]  
Disclosure of significant investments in associates and joint ventures [line items]  
Principal Associates, Country of Incorporation Cambodia
Principal Associates, Proportion of Ownership Interest 18.00% [1]
Principal Associates, Proportion of Voting Rights 18.00% [1]
Principal Associates, Main Business Commercial banking
Vietnam Prosperity Joint-Stock Commercial Bank [member]  
Disclosure of significant investments in associates and joint ventures [line items]  
Principal Associates, Country of Incorporation Vietnam
Principal Associates, Proportion of Ownership Interest 15.00% [1]
Principal Associates, Proportion of Voting Rights 15.00% [1]
Principal Associates, Main Business Commercial banking
Rizal Commercial Banking Corporation [Member]  
Disclosure of significant investments in associates and joint ventures [line items]  
Principal Associates, Country of Incorporation Philippines
Principal Associates, Proportion of Ownership Interest 24.40% [1]
Principal Associates, Proportion of Voting Rights 24.40% [1]
Principal Associates, Main Business Commercial banking
Sumitomo Mitsui Auto Service Company, Limited [member]  
Disclosure of significant investments in associates and joint ventures [line items]  
Principal Associates, Country of Incorporation Japan
Principal Associates, Proportion of Ownership Interest 26.10% [1]
Principal Associates, Proportion of Voting Rights 26.10% [1]
Principal Associates, Main Business Leasing
SMBC Aviation Capital Limited [member]  
Disclosure of significant investments in associates and joint ventures [line items]  
Principal Associates, Country of Incorporation Ireland
Principal Associates, Proportion of Ownership Interest 32.00% [1]
Principal Associates, Proportion of Voting Rights 32.00% [1]
Principal Associates, Main Business Leasing
POCKET CARD CO., LTD. [member]  
Disclosure of significant investments in associates and joint ventures [line items]  
Principal Associates, Country of Incorporation Japan
Principal Associates, Proportion of Ownership Interest 20.00% [1]
Principal Associates, Proportion of Voting Rights 20.00% [1]
Principal Associates, Main Business Credit card
VPBank SMBC Finance Company Limited [member]  
Disclosure of significant investments in associates and joint ventures [line items]  
Principal Associates, Country of Incorporation Vietnam
Principal Associates, Proportion of Ownership Interest 49.00% [1]
Principal Associates, Proportion of Voting Rights 49.00% [1]
Principal Associates, Main Business Consumer lending
SAKURA KCS Corporation [member]  
Disclosure of significant investments in associates and joint ventures [line items]  
Principal Associates, Country of Incorporation Japan
Principal Associates, Proportion of Ownership Interest 29.70% [1]
Principal Associates, Proportion of Voting Rights 29.70% [1]
Principal Associates, Main Business System engineering and data processing
JSOL Corporation [member]  
Disclosure of significant investments in associates and joint ventures [line items]  
Principal Associates, Country of Incorporation Japan
Principal Associates, Proportion of Ownership Interest 50.00% [1]
Principal Associates, Proportion of Voting Rights 50.00% [1]
Principal Associates, Main Business System development and data processing
Sakura Information Systems Co., Ltd. [member]  
Disclosure of significant investments in associates and joint ventures [line items]  
Principal Associates, Country of Incorporation Japan
Principal Associates, Proportion of Ownership Interest 49.00% [1]
Principal Associates, Proportion of Voting Rights 49.00% [1]
Principal Associates, Main Business System engineering and data processing
China Post & Capital Fund Management Co., Ltd. [member]  
Disclosure of significant investments in associates and joint ventures [line items]  
Principal Associates, Country of Incorporation China
Principal Associates, Proportion of Ownership Interest 23.60% [1]
Principal Associates, Proportion of Voting Rights 23.60% [1]
Principal Associates, Main Business Investment management, and investment advisory and agency
[1] Percentages of proportion of ownership interest and proportion of voting rights have been truncated.