XML 53 R39.htm IDEA: XBRL DOCUMENT
v3.22.2.2

FAIR VALUE OF FINANCIAL INSTRUMENTS, Liabilities Measured at Fair Value (Details) - USD ($) | Jul. 12, 2022 | Sep. 30, 2022 | Jul. 14, 2022 | Mar. 09, 2022 | Mar. 06, 2022 | Dec. 31, 2021
--- | --- | --- | --- | --- | --- | ---
Liabilities [Abstract] |  |  |  |  |  |
Liabilities, fair value disclosure |  |  |  |  |  | $ 0
PIPE Investor [Member] |  |  |  |  |  |
Liabilities [Abstract] |  |  |  |  |  |
Warrants outstanding (in shares) | 0 |  |  |  |  |
Pre-funded Warrants [Member] |  |  |  |  |  |
Liabilities [Abstract] |  |  |  |  |  |
Warrants exercisable (in shares) |  |  |  | 68,000 |  |
Warrants exercise price (in dollars per share) |  |  |  |  | $ 0.1 |
Pre-funded Warrants [Member] | PIPE Investor [Member] |  |  |  |  |  |
Liabilities [Abstract] |  |  |  |  |  |
Warrants exercised (in shares) | 68,000 |  |  |  |  |
Warrants exercise price (in dollars per share) | $ 0.1 |  |  |  |  |
Aggregate exercise price | $ 6,786 |  |  |  |  |
Warrants outstanding (in shares) | 0 |  |  |  |  |
Common Warrants [Member] |  |  |  |  |  |
Liabilities [Abstract] |  |  |  |  |  |
Warrants exercisable (in shares) |  |  |  | 343,000 |  |
Warrants exercise price (in dollars per share) |  | $ 38.2 |  |  | $ 38.2 |
Warrants outstanding (in shares) |  | 343,000 |  |  |  |
Common Warrants [Member] | PIPE Investor [Member] |  |  |  |  |  |
Liabilities [Abstract] |  |  |  |  |  |
Warrants exercisable (in shares) |  |  | 68,000 |  |  |
Level 1 [Member] |  |  |  |  |  |
Liabilities [Abstract] |  |  |  |  |  |
Liabilities, fair value disclosure |  | $ 0 |  |  |  |
Level 1 [Member] | Common Warrants [Member] | Warrant Liabilities [Member] |  |  |  |  |  |
Liabilities [Abstract] |  |  |  |  |  |
Liabilities, fair value disclosure |  | 0 |  |  |  |
Level 2 [Member] |  |  |  |  |  |
Liabilities [Abstract] |  |  |  |  |  |
Liabilities, fair value disclosure |  | 0 |  |  |  |
Level 2 [Member] | Common Warrants [Member] | Warrant Liabilities [Member] |  |  |  |  |  |
Liabilities [Abstract] |  |  |  |  |  |
Liabilities, fair value disclosure |  | 0 |  |  |  |
Level 3 [Member] |  |  |  |  |  |
Liabilities [Abstract] |  |  |  |  |  |
Liabilities, fair value disclosure |  | 633,000 |  |  |  |
Level 3 [Member] | Common Warrants [Member] | Warrant Liabilities [Member] |  |  |  |  |  |
Liabilities [Abstract] |  |  |  |  |  |
Liabilities, fair value disclosure |  | $ 633,000 |  |  |  |

X
- Definition Number of warrants or rights exercised during the period. + References No definition available. + Details
Name: | erna_ClassOfWarrantOrRightExercised
Namespace Prefix: | erna_
Data Type: | xbrli:sharesItemType
Balance Type: | na
Period Type: | duration

X
- Definition Exercise price per share or per unit of warrants or rights outstanding. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 505 -SubTopic 10 -Section 50 -Paragraph 3 -URI https://asc.fasb.org/extlink&oid=126973232&loc=d3e21475-112644 + Details
Name: | us-gaap_ClassOfWarrantOrRightExercisePriceOfWarrantsOrRights1
Namespace Prefix: | us-gaap_
Data Type: | dtr-types:perShareItemType
Balance Type: | na
Period Type: | instant

X
- Definition Number of securities into which the class of warrant or right may be converted. For example, but not limited to, 500,000 warrants may be converted into 1,000,000 shares. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 505 -SubTopic 10 -Section 50 -Paragraph 3 -URI https://asc.fasb.org/extlink&oid=126973232&loc=d3e21475-112644 + Details
Name: | us-gaap_ClassOfWarrantOrRightNumberOfSecuritiesCalledByWarrantsOrRights
Namespace Prefix: | us-gaap_
Data Type: | xbrli:sharesItemType
Balance Type: | na
Period Type: | instant

X
- Definition Number of warrants or rights outstanding. + References No definition available. + Details
Name: | us-gaap_ClassOfWarrantOrRightOutstanding
Namespace Prefix: | us-gaap_
Data Type: | xbrli:sharesItemType
Balance Type: | na
Period Type: | instant

X
- Definition Fair value of financial and nonfinancial obligations. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 820 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (a) -URI https://asc.fasb.org/extlink&oid=126976982&loc=d3e19207-110258 + Details
Name: | us-gaap_LiabilitiesFairValueDisclosure
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- References No definition available. + Details
Name: | us-gaap_LiabilitiesFairValueDisclosureAbstract
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition The cash inflow from issuance of rights to purchase common shares at predetermined price (usually issued together with corporate debt). + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 14 -Subparagraph (a) -URI https://asc.fasb.org/extlink&oid=126954810&loc=d3e3255-108585 + Details
Name: | us-gaap_ProceedsFromIssuanceOfWarrants
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Details
Name: | us-gaap_InvestmentTypeAxis=erna_PIPEInvestorMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_ClassOfWarrantOrRightAxis=erna_PreFundedWarrantsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_ClassOfWarrantOrRightAxis=erna_CommonWarrantsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FairValueByFairValueHierarchyLevelAxis=us-gaap_FairValueInputsLevel1Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FairValueByLiabilityClassAxis=us-gaap_DerivativeFinancialInstrumentsLiabilitiesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FairValueByFairValueHierarchyLevelAxis=us-gaap_FairValueInputsLevel2Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FairValueByFairValueHierarchyLevelAxis=us-gaap_FairValueInputsLevel3Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |