No definition available.

Name:	erna_LegalMattersAbstract
Namespace Prefix:	erna_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

The percentage of equity promised to the plaintiff seeks in the legal matter.

+ References

No definition available.

+ Details

Name:	erna_LossContingencyDamagesSoughtExpectedEquityPercentage
Namespace Prefix:	erna_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

The monetary amount of salary promised to the plaintiff seeks in the legal matter.

+ References

No definition available.

+ Details

Name:	erna_LossContingencyDamagesSoughtExpectedSalary
Namespace Prefix:	erna_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Represents the number member in arbitration panel pertaining to a loss contingency during the period.

+ References

No definition available.

+ Details

Name:	erna_LossContingencyNumberOfArbitrationPanel
Namespace Prefix:	erna_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount awarded to other party in judgment or settlement of litigation.

+ References

No definition available.

+ Details

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

- Definition

The value (monetary amount) of the award the plaintiff seeks in the legal matter.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 450
-SubTopic 20
-Section 50
-Paragraph 4
-Subparagraph (a)
-URI https://asc.fasb.org/extlink&oid=121557415&loc=d3e14435-108349

Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 450
-SubTopic 20
-Section 50
-Paragraph 1
-URI https://asc.fasb.org/extlink&oid=121557415&loc=d3e14326-108349

Reference 3: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 450
-SubTopic 20
-Section 50
-Paragraph 9
-Subparagraph (a)
-URI https://asc.fasb.org/extlink&oid=121557415&loc=d3e14557-108349

+ Details

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

- Details

Name:	us-gaap_RelatedPartyTransactionsByRelatedPartyAxis=erna_NovellusTherapeuticsLimitedMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_RangeAxis=srt_MinimumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_RelatedPartyTransactionsByRelatedPartyAxis=erna_DheshGovenderMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

COMMITMENTS AND CONTINGENCIES, Legal Matters (Details) $ in Millions	Aug. 05, 2022 USD ($)	Dec. 15, 2021 USD ($) BoardMember	Feb. 05, 2021 USD ($)
Legal Matters [Abstract]
Litigation settlement, amount	$ 1.2
Novellus, Ltd. [Member]
Legal Matters [Abstract]
Defendants salary promised against plaintiff			$ 0.5
Percentage of equity promised against plaintiff			7.00%
Novellus, Ltd. [Member] \| Minimum [Member]
Legal Matters [Abstract]
Loss contingency, damages sought, value			$ 10.0
Govender [Member]
Legal Matters [Abstract]
Defendants salary promised against plaintiff		$ 0.5
Percentage of equity promised against plaintiff		7.00%
Number of member arbitration panel \| BoardMember		3
Govender [Member] \| Minimum [Member]
Legal Matters [Abstract]
Loss contingency, damages sought, value		$ 100.0