Cash and Deposits with Banks - Additional Information (Detail) - JPY (¥) ¥ in Millions	Mar. 31, 2026	Mar. 31, 2025	Mar. 31, 2024
Cash and cash equivalents [abstract]
Reserves funds required to be maintained by the SMBC Group	¥ 2,234,643	¥ 2,231,539	¥ 1,983,987

The amount of reserve that is kept in deposit at a central bank to fulfil regulatory reserve requirements.

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Note Expiry date 2027-01-01
-Name IAS
-Number 1
-IssueDate 2025-01-01
-Paragraph 112
-Subparagraph c
-URI https://taxonomy.ifrs.org/xifrs-link?type=IAS&num=1&code=ifrs-tx-2025-en-b&anchor=para_112_c&doctype=Standard
-URIDate 2025-03-27

Name:	ifrs-full_MandatoryReserveDepositsAtCentralBanks
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant