Fair values of financial instruments carried at fair value - Sensitivity of Level 3 fair values to reasonably possible alternative assumptions (Details) $ in Millions	6 Months Ended	12 Months Ended
Jun. 30, 2026 USD ($) category	Jun. 30, 2025 USD ($)	Dec. 31, 2025 USD ($)
Disclosure Of Fair Value Measurement Of Assets And Liabilities [Line Items]
Favourable changes reflected in profit or loss	$ 2,449	$ 2,416	$ 2,233
Unfavourable changes reflected in profit or loss	(1,785)	(1,798)	(1,729)
Favourable changes reflected in OCI	68	52	49
Unfavourable changes reflected in OCI	$ (52)	(55)	(49)
Number of financial instrument categories \| category	1
Confidence level	95.00%
Derivatives, trading assets and trading liabilities \| Derivatives, trading liabilities
Disclosure Of Fair Value Measurement Of Assets And Liabilities [Line Items]
Favourable changes reflected in profit or loss	$ 593	524	483
Unfavourable changes reflected in profit or loss	(327)	(309)	(295)
Favourable changes reflected in OCI	0	0	0
Unfavourable changes reflected in OCI	0	0	0
Financial assets designated and otherwise mandatorily measured at fair value through profit or loss \| Financial liabilities designated at fair value
Disclosure Of Fair Value Measurement Of Assets And Liabilities [Line Items]
Favourable changes reflected in profit or loss	1,856	1,873	1,750
Unfavourable changes reflected in profit or loss	(1,458)	(1,470)	(1,434)
Favourable changes reflected in OCI	0	0	0
Unfavourable changes reflected in OCI	0	0	0
Financial investments
Disclosure Of Fair Value Measurement Of Assets And Liabilities [Line Items]
Favourable changes reflected in profit or loss	0	19	0
Unfavourable changes reflected in profit or loss	0	(19)	0
Favourable changes reflected in OCI	68	52	49
Unfavourable changes reflected in OCI	$ (52)	$ (55)	$ (49)

[Line Items] for Disclosure Of Fair Value Measurement Of Assets And Liabilities [Table]

No definition available.

Name:	hsbc_DisclosureOfFairValueMeasurementOfAssetsAndLiabilitiesLineItems
Namespace Prefix:	hsbc_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Gain (Loss) Recognized In Other Comprehensive Income Due to Favourable Changes In Significant Unobservable Inputs

+ References

No definition available.

+ Details

Name:	hsbc_GainLossRecognizedInOtherComprehensiveIncomeDueToFavourableChangesInSignificantUnobservableInputs
Namespace Prefix:	hsbc_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Gain (Loss) Recognized In Other Comprehensive Income Due to Unfavourable Changes In Significant Unobservable Inputs

+ References

No definition available.

+ Details

Name:	hsbc_GainLossRecognizedInOtherComprehensiveIncomeDueToUnfavourableChangesInSignificantUnobservableInputs
Namespace Prefix:	hsbc_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Gain (Loss) Recognized In Profit Or Loss Due to Favourable Changes In Significant Unobservable Inputs

+ References

No definition available.

+ Details

Name:	hsbc_GainLossRecognizedInProfitOrLossDueToFavourableChangesInSignificantUnobservableInputs
Namespace Prefix:	hsbc_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Gain (Loss) Recognized In Profit Or Loss Due to Unfavourable Changes In Significant Unobservable Inputs

+ References

No definition available.

+ Details

Name:	hsbc_GainLossRecognizedInProfitOrLossDueToUnfavourableChangesInSignificantUnobservableInputs
Namespace Prefix:	hsbc_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Number Of Financial Instrument Categories

+ References

No definition available.

+ Details

Name:	hsbc_NumberOfFinancialInstrumentCategories
Namespace Prefix:	hsbc_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Definition

The confidence level corresponding to the results of a technique other than the confidence level technique used for determining the risk adjustment for non-financial risk. [Refer: Risk adjustment for non-financial risk [member]]

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IFRS
-Number 17
-IssueDate 2025-01-01
-Paragraph 119
-URI https://taxonomy.ifrs.org/xifrs-link?type=IFRS&num=17&code=ifrs-tx-2025-en-r&anchor=para_119&doctype=Standard
-URIDate 2025-03-27

+ Details

Name:	ifrs-full_ConfidenceLevelCorrespondingToResultsOfTechniqueOtherThanConfidenceLevelTechniqueUsedForDeterminingRiskAdjustmentForNonfinancialRisk
Namespace Prefix:	ifrs-full_
Data Type:	dtr-2022:percentItemType
Balance Type:	na
Period Type:	instant

- Details

Name:	ifrs-full_CategoriesOfFinancialAssetsAxis=hsbc_FinancialAssetsAtFairValueThroughProfitOrLossClassifiedAsHeldForTradingAndDerivativesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	ifrs-full_CategoriesOfFinancialLiabilitiesAxis=hsbc_FinancialLiabilitiesAtFairValueThroughProfitOrLossClassifiedAsHeldForTradingAndDerivativesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	ifrs-full_CategoriesOfFinancialAssetsAxis=ifrs-full_FinancialAssetsAtFairValueThroughProfitOrLossDesignatedUponInitialRecognitionCategoryMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	ifrs-full_CategoriesOfFinancialLiabilitiesAxis=ifrs-full_FinancialLiabilitiesAtFairValueThroughProfitOrLossDesignatedUponInitialRecognitionCategoryMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	ifrs-full_CategoriesOfFinancialAssetsAxis=ifrs-full_FinancialAssetsAtFairValueThroughOtherComprehensiveIncomeCategoryMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: