Investments in Associates and Joint Ventures - Summary of Investments in Associates and Joint Ventures (Detail)	12 Months Ended
Mar. 31, 2024
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%
Principal Joint Venture, Proportion of Voting Rights	50.00%
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	46.50%
Principal Associates, Proportion of Voting Rights	46.50%
Principal Associates, Main Business	Internet banking
The Bank of East Asia, Limited [member]
Disclosure of significant investments in associates and joint ventures [line items]
Principal Associates, Country of Incorporation	China
Principal Associates, Proportion of Ownership Interest	21.70%
Principal Associates, Proportion of Voting Rights	21.70%
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%
Principal Associates, Proportion of Voting Rights	18.00%
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%
Principal Associates, Proportion of Voting Rights	15.00%
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	20.00%
Principal Associates, Proportion of Voting Rights	20.00%
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%
Principal Associates, Proportion of Voting Rights	26.10%
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%
Principal Associates, Proportion of Voting Rights	32.00%
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%
Principal Associates, Proportion of Voting Rights	20.00%
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%
Principal Associates, Proportion of Voting Rights	49.00%
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%
Principal Associates, Proportion of Voting Rights	29.70%
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%
Principal Associates, Proportion of Voting Rights	50.00%
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%
Principal Associates, Proportion of Voting Rights	49.00%
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%
Principal Associates, Proportion of Voting Rights	23.60%
Principal Associates, Main Business	Investment management, and investment advisory and agency

The country in which a joint venture of the entity is incorporated. [Refer: Joint ventures [member]]

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IAS
-Number 27
-IssueDate 2023-01-01
-Paragraph 16
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-URIDate 2023-03-23

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Name IAS
-Number 27
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Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Name IFRS
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-IssueDate 2023-01-01
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- Definition

The country in which an associate of the entity is incorporated. [Refer: Associates [member]]

+ References

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- Definition

The proportion of ownership interest in an associate attributable to the entity. [Refer: Associates [member]]

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IAS
-Number 27
-IssueDate 2023-01-01
-Paragraph 17
-Subparagraph b
-Clause iii
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-URIDate 2023-03-23

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Name IAS
-Number 27
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-Paragraph 16
-Subparagraph b
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-URI https://taxonomy.ifrs.org/xifrs-link?type=IAS&num=27&code=ifrs-tx-2023-en-r&anchor=para_16_b_iii&doctype=Standard
-URIDate 2023-03-23

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Name IFRS
-Number 12
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- Definition

The proportion of ownership interest in a joint venture attributable to the entity. [Refer: Joint ventures [member]]

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The proportion of the voting rights in an associate held by the entity. [Refer: Associates [member]]

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- Definition

The proportion of the voting rights in a joint venture held by the entity. [Refer: Joint ventures [member]]

+ References

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- Definition

The description of main business of associate.

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No definition available.

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The description of main business of joint venture.

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