Net Investment Income - Additional Information (Detail) - JPY (¥) ¥ in Millions	12 Months Ended
Mar. 31, 2026	Mar. 31, 2025	Mar. 31, 2024
Material income and expense [abstract]
Dividend income from equity instruments at fair value through other comprehensive income derecognized	¥ 3,829	¥ 4,708	¥ 5,015

The amount of dividends related to investments in equity instruments that the entity has designated at fair value through other comprehensive income, derecognised during the reporting period. [Refer: Investments in equity instruments designated at fair value through other comprehensive income [member]]

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IFRS
-Number 7
-IssueDate 2025-01-01
-Paragraph 11A
-Subparagraph d
-URI https://taxonomy.ifrs.org/xifrs-link?type=IFRS&num=7&code=ifrs-tx-2025-en-r&anchor=para_11A_d&doctype=Standard
-URIDate 2025-03-27

Name:	ifrs-full_DividendsRecognisedForInvestmentsInEquityInstrumentsDesignatedAsMeasuredAtFairValueThroughOtherComprehensiveIncomeDerecognisedDuringPeriod
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration