Equity Attributable To Other Equity Instruments Holders - Additional Information (Detail)	Mar. 31, 2026
Equity [abstract]
Common Equity Tier 1 capital ratio threshold where bonds may be written down	5.125%

Triggering percentage of common equity Tier 1 capital where bonds may be written down.

No definition available.

Name:	smfg_TriggeringPercentageOfCommonEquityTierOneCapitalWhereBondsMayBeWrittenDown
Namespace Prefix:	smfg_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	instant