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v3.23.1

Equity and Warrants,Warrants activity (Details) | 12 Months Ended
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Dec. 31, 2022 shares
Warrant Activity Abstract |
Beginning balance (in shares) | 0
Granted (in shares) | 4,781
Exercised (in shares) | (68)
Ending balance (in shares) | 4,713
March 2022 Warrants [Member] |
Warrant Activity Abstract |
Beginning balance (in shares) | 0
Granted (in shares) | 343
Exercised (in shares) | 0
Ending balance (in shares) | 343
Pre-funded Warrants [Member] |
Warrant Activity Abstract |
Beginning balance (in shares) | 0
Granted (in shares) | 68
Exercised (in shares) | (68)
Ending balance (in shares) | 0
November 2022 Warrants [Member] |
Warrant Activity Abstract |
Beginning balance (in shares) | 0
Granted (in shares) | 4,370
Exercised (in shares) | 0
Ending balance (in shares) | 4,370

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

X
- Definition The number of grants made during the period on warrants. + References No definition available. + Details
Name: | erna_ClassOfWarrantOrRightGrantsInPeriod
Namespace Prefix: | erna_
Data Type: | xbrli:sharesItemType
Balance Type: | na
Period Type: | duration

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

X
- Details
Name: | us-gaap_ClassOfWarrantOrRightAxis=erna_March2022WarrantsMember
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_November2022WarrantsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |