XML 67 R48.htm IDEA: XBRL DOCUMENT v3.20.4

Accrued Expenses - Additional Information (Details) $ in Millions	Dec. 31, 2020 USD ($)
Chief Executive Officer
Deferred Compensation Arrangement With Individual Share Based Payments [Line Items]
Accrued Severance Cost	$ 0.3

X

- Definition

Accrued severance cost.

+ References

No definition available.

+ Details

Name:	hsdt_AccruedSeveranceCost
Namespace Prefix:	hsdt_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

X

- Definition

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

+ References

No definition available.

+ Details

Name:	us-gaap_DeferredCompensationArrangementWithIndividualShareBasedPaymentsLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

X

- Details

Name:	srt_TitleOfIndividualAxis=srt_ChiefExecutiveOfficerMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: