Principal Subsidiaries - Principal Foreign Subsidiaries (Parenthetical) (Detail)	12 Months Ended
Mar. 31, 2025	Mar. 31, 2021
Business combinations [member] \| SMBC Group [member]
Disclosure of subsidiaries [Line Items]
Proportion of Disposed Interest	3.70%	3.70%

Line items represent concepts included in a table. These concepts are used to disclose reportable information associated with members defined in one or many axes of the table.

No definition available.

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Period Type:	duration