Provisions - Sensitivity analysis of inbound and outbound claims (Details) $ in Millions	Jun. 30, 2018 USD ($)
Other Provisions, Contingent Liabilities And Contingent Assets [Abstract]
Increase (decrease) in redress provision due to reasonably possible increase in inbound claims	$ 268

Increase (Decrease) In Redress Provision Due To Reasonably Possible Increase In Inbound Claims

No definition available.

Name:	hsbc_IncreaseDecreaseInRedressProvisionDueToReasonablyPossibleIncreaseInInboundClaims
Namespace Prefix:	hsbc_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant