v3.25.1

Leases - Narrative (Details) - USD ($) $ in Thousands	1 Months Ended	3 Months Ended
Leases - Narrative (Details) - USD ($) $ in Thousands	Mar. 31, 2025	Mar. 31, 2025	Mar. 31, 2024	Feb. 18, 2025	Jul. 27, 2021	May 23, 2021
Lessee, Lease, Description [Line Items]
Operating lease right-of-use asset		$ 861	$ 0
Operating lease right-of-use asset		1,494	$ 0
Office Space in Pasadena, California
Lessee, Lease, Description [Line Items]
Lessee, operating lease, term of contract						7 years
Operating lease right-of-use asset		900
Manufacturing space in Long Beach, California
Lessee, Lease, Description [Line Items]
Lessee, operating lease, term of contract					5 years
Letters of credit					$ 1,500
Operating lease termination fee				$ 800
Operating lease right-of-use asset		1,500
Operating lease liability removed upon lease termination	$ 2,800	2,800
Gain on termination of lease		$ (500)
Letters of credit. outstanding released amount	$ 1,500

Letters Of Credit. Outstanding Released Amount

+ References

No definition available.

+ Details

Name:	hlg_LettersOfCredit.OutstandingReleasedAmount
Namespace Prefix:	hlg_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Operating Lease, Operating Lease Liability Removed Upon Lease Termination

+ References

No definition available.

+ Details

Name:	hlg_OperatingLeaseOperatingLeaseLiabilityRemovedUponLeaseTermination
Namespace Prefix:	hlg_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Operating Lease, Right-of-Use Asset Removed Upon Lease Termination

+ References

No definition available.

+ Details

Name:	hlg_OperatingLeaseRightOfUseAssetRemovedUponLeaseTermination
Namespace Prefix:	hlg_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Operating Lease, Termination Fee

+ References

No definition available.

+ Details

Name:	hlg_OperatingLeaseTerminationFee
Namespace Prefix:	hlg_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount of gain (loss) on termination of lease before expiration of lease term.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 842
-SubTopic 20
-Name Accounting Standards Codification
-Section 40
-Paragraph 1
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479092/842-20-40-1

+ Details

Name:	us-gaap_GainLossOnTerminationOfLease
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- 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

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 842
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 7A
-Subparagraph (c)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147478964/842-20-50-7A

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 842
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 3
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147478964/842-20-50-3

+ Details

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

- Definition

Term of lessee's operating lease, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 842
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 3
-Subparagraph (a)(3)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147478964/842-20-50-3

+ Details

Name:	us-gaap_LesseeOperatingLeaseTermOfContract
Namespace Prefix:	us-gaap_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	instant

- Definition

The total amount of the contingent obligation under letters of credit outstanding as of the reporting date.

+ References

No definition available.

+ Details

Name:	us-gaap_LettersOfCreditOutstandingAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount of loss from impairment of right-of-use asset from operating lease.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 842
-SubTopic 20
-Name Accounting Standards Codification
-Section 25
-Paragraph 6
-Subparagraph (c)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479365/842-20-25-6

+ Details

Name:	us-gaap_OperatingLeaseImpairmentLoss
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Details

Name:	hlg_LesseeLeaseArrangementAxis=hlg_OfficeSpaceInPasadenaCaliforniaMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	hlg_LesseeLeaseArrangementAxis=hlg_ManufacturingSpaceInLongBeachCaliforniaMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Heliogen, Inc. 10-Q