XML 31 R22.htm IDEA: XBRL DOCUMENT
v3.22.2

Organization and Basis of Presentation - Additional Information (Details) - USD ($) | 1 Months Ended | 2 Months Ended | 6 Months Ended
--- | --- | --- | ---
Jul. 31, 2022 | Mar. 31, 2021 | Nov. 30, 2021 | Jun. 30, 2022 | Jun. 30, 2021
Subsidiary Sale Of Stock [Line Items] |  |  |  |  |
Date of incorporation |  |  |  | Jun. 30, 2019 |
Proceeds from issuance of common stock, net of commissions and offering expenses |  |  |  | $ 43,000 | $ 83,000
Liability related to public offering |  |  |  | 28,186,000 |
Cash and cash equivalents and short term available-for-sale securities |  |  |  | $ 139,300,000 |
Public Offerings | Subsequent Event |  |  |  |  |
Subsidiary Sale Of Stock [Line Items] |  |  |  |  |
Shares issued and sold | 18,675,466 |  |  |  |
Proceeds from issuance of common stock, net of commissions and offering expenses | $ 88,200,000 |  |  |  |
Offering price per share | $ 3.55 |  |  |  |
Warrant exercise price | $ 5.325 |  |  |  |
Underwriting discounts and commissions | $ 5,700,000 |  |  |  |
Other offering costs | $ 600,000 |  |  |  |
Public Offerings | Pre-Funded Warrants | Subsequent Event |  |  |  |  |
Subsidiary Sale Of Stock [Line Items] |  |  |  |  |
Warrants to purchase shares of common stock | 3,972,126 |  |  |  |
Number of pre-funded warrants issued | 7,944,252 |  |  |  |
Offering price per warrant | $ 3.549 |  |  |  |
Public Offerings | Minimum [Member] | Subsequent Event |  |  |  |  |
Subsidiary Sale Of Stock [Line Items] |  |  |  |  |
Warrants to purchase shares of common stock | 9,337,733 |  |  |  |
Public Offerings | A T M Facility |  |  |  |  |
Subsidiary Sale Of Stock [Line Items] |  |  |  |  |
Shares issued and sold |  |  |  | 0 |
Public Offerings | A T M Facility | Maximum |  |  |  |  |
Subsidiary Sale Of Stock [Line Items] |  |  |  |  |
Maximum amount of equity shares issuable |  | $ 75,000,000.0 |  |  |
Public Offerings | SVB Leerink LLC |  |  |  |  |
Subsidiary Sale Of Stock [Line Items] |  |  |  |  |
Shares issued and sold |  |  | 186,546 |  |
Selling commission per shares sold percentage |  | 3.00% |  |  |
Proceeds from issuance of common stock, net of commissions and offering expenses |  |  | $ 3,300,000 |  |
Issuance of common stock, weighted average price per share |  |  | $ 17.97 |  |

X
- Definition Date when an entity was incorporated + References No definition available. + Details
Name: | dei_EntityIncorporationDateOfIncorporation
Namespace Prefix: | dei_
Data Type: | xbrli:dateItemType
Balance Type: | na
Period Type: | duration

X
- Definition Common stock and warrants combined offering price per share. + References No definition available. + Details
Name: | etnb_CommonStockAndWarrantsCombinedOfferingPricePerShare
Namespace Prefix: | etnb_
Data Type: | dtr-types:perShareItemType
Balance Type: | na
Period Type: | instant

X
- Definition Liability related to public offering. + References No definition available. + Details
Name: | etnb_LiabilityRelatedToPublicOffering
Namespace Prefix: | etnb_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Maximum amount of equity shares issuable. + References No definition available. + Details
Name: | etnb_MaximumAmountOfEquitySharesIssuable
Namespace Prefix: | etnb_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Number of pre-funded warrants issued. + References No definition available. + Details
Name: | etnb_NumberOfPreFundedWarrantsIssued
Namespace Prefix: | etnb_
Data Type: | xbrli:sharesItemType
Balance Type: | na
Period Type: | duration

X
- Definition Offering price per warrant. + References No definition available. + Details
Name: | etnb_OfferingPricePerWarrant
Namespace Prefix: | etnb_
Data Type: | dtr-types:perShareItemType
Balance Type: | na
Period Type: | instant

X
- Definition Selling commission per shares sold percentage. + References No definition available. + Details
Name: | etnb_SellingCommissionPerSharesSoldPercentage
Namespace Prefix: | etnb_
Data Type: | dtr-types:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition Underwriting discounts and commissions. + References No definition available. + Details
Name: | etnb_UnderwritingDiscountsAndCommissions
Namespace Prefix: | etnb_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Cash includes currency on hand as well as demand deposits with banks or financial institutions. It also includes other kinds of accounts that have the general characteristics of demand deposits in that the customer may deposit additional funds at any time and effectively may withdraw funds at any time without prior notice or penalty. Cash equivalents, excluding items classified as marketable securities, include short-term, highly liquid Investments that are both readily convertible to known amounts of cash, and so near their maturity that they present minimal risk of changes in value because of changes in interest rates. Generally, only investments with original maturities of three months or less qualify under that definition. Original maturity means original maturity to the entity holding the investment. For example, both a three-month US Treasury bill and a three-year Treasury note purchased three months from maturity qualify as cash equivalents. However, a Treasury note purchased three years ago does not become a cash equivalent when its remaining maturity is three months. Short-term investments, exclusive of cash equivalents, generally consist of marketable securities intended to be sold within one year (or the normal operating cycle if longer) and may include trading securities, available-for-sale securities, or held-to-maturity securities (if maturing within one year), as applicable. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02(9)) -URI https://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682 + Details
Name: | us-gaap_CashCashEquivalentsAndShortTermInvestments
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

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 The cash outflow for cost incurred directly with the issuance of an equity security. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 15 -URI https://asc.fasb.org/extlink&oid=126954810&loc=d3e3291-108585 + Details
Name: | us-gaap_PaymentsOfStockIssuanceCosts
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition The cash inflow from the additional capital contribution to the entity. + 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_ProceedsFromIssuanceOfCommonStock
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Per share or per unit amount of equity securities issued. + References No definition available. + Details
Name: | us-gaap_SharesIssuedPricePerShare
Namespace Prefix: | us-gaap_
Data Type: | dtr-types:perShareItemType
Balance Type: | na
Period Type: | instant

X
- Definition Number of new stock issued during the period. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02(29)) -URI https://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 505 -SubTopic 10 -Section 50 -Paragraph 2 -URI https://asc.fasb.org/extlink&oid=126973232&loc=d3e21463-112644 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 505 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.3-04) -URI https://asc.fasb.org/extlink&oid=120397183&loc=d3e187085-122770 Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02(28)) -URI https://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682 + Details
Name: | us-gaap_StockIssuedDuringPeriodSharesNewIssues
Namespace Prefix: | us-gaap_
Data Type: | xbrli:sharesItemType
Balance Type: | na
Period Type: | duration

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_SubsidiarySaleOfStockLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Details
Name: | us-gaap_SubsidiarySaleOfStockAxis=us-gaap_IPOMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_SubsequentEventTypeAxis=us-gaap_SubsequentEventMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_StatementEquityComponentsAxis=etnb_PreFundedWarrantsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_RangeAxis=srt_MinimumMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_TypeOfArrangementAxis=etnb_ATMFacilityMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_RangeAxis=srt_MaximumMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_TypeOfArrangementAxis=etnb_SVBLeerinkLLCAndCantorFitzgeraldCoMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |