XML 41 R33.htm IDEA: XBRL DOCUMENT
v3.26.1

Nature of the Business and Basis of Presentation - Additional Information (Detail) - USD ($) $ in Thousands |  | 3 Months Ended | 6 Months Ended |  |
--- | --- | --- | --- | --- | ---
Feb. 12, 2026 | Jun. 30, 2026 | Jun. 30, 2025 | Jun. 30, 2026 | Jun. 30, 2025 | Jul. 01, 2026 | Dec. 31, 2025
Nature Of Business And Basis Of Presentation [Line Items] |  |  |  |  |  |  |
Entity incorporated month and year |  |  |  | 2010-10 |  |  |
Restructuring and related cost, number of positions eliminated, period percent | 30.00% |  |  |  |  |  |
Restructuring costs |  |  |  | $ 914 |  |  |
Severance costs |  |  |  | $ 718 |  |  |
Entity incorporation, state or country code |  |  |  | DE |  |  |
Loss from operations |  | $ (21,273) | $ (24,881) | $ (42,180) | $ (52,117) |  |
Milestone Payment Due |  | $ 12,500 |  | $ 12,500 |  |  |
Milestone Payment date |  | Oct. 01, 2026 |  | Oct. 01, 2026 |  |  |
Accumulated deficit |  | $ (987,735) |  | $ (987,735) |  |  | $ (972,403)
Cash and cash equivalents |  | $ 15,594 |  | $ 15,594 |  |  | 45,766
Subsequent Event [Member] |  |  |  |  |  |  |
Nature Of Business And Basis Of Presentation [Line Items] |  |  |  |  |  |  |
Milestone Payments Received |  |  |  |  |  | $ 12,500 |
CARB-X [Member] | Maximum [Member] |  |  |  |  |  |  |
Nature Of Business And Basis Of Presentation [Line Items] |  |  |  |  |  |  |
Grant Received for Clinical Development |  |  |  |  |  |  | $ 3,583

X
- Definition Two-character EDGAR code representing the state or country of incorporation. + References No definition available. + Details
Name: | dei_EntityIncorporationStateCountryCode
Namespace Prefix: | dei_
Data Type: | dei:edgarStateCountryItemType
Balance Type: | na
Period Type: | duration

X
- Definition Entity incorporation month and year of incorporation. + References No definition available. + Details
Name: | mcrb_EntityIncorporationMonthAndYearOfIncorporation
Namespace Prefix: | mcrb_
Data Type: | xbrli:gYearMonthItemType
Balance Type: | na
Period Type: | duration

X
- Definition Grant received for clinical development. + References No definition available. + Details
Name: | mcrb_GrantReceivedForClinicalDevelopment
Namespace Prefix: | mcrb_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Milestone payment date + References No definition available. + Details
Name: | mcrb_MilestonePaymentDate
Namespace Prefix: | mcrb_
Data Type: | xbrli:dateItemType
Balance Type: | na
Period Type: | instant

X
- Definition Milestone payment due. + References No definition available. + Details
Name: | mcrb_MilestonePaymentDue
Namespace Prefix: | mcrb_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Milestone payments received. + References No definition available. + Details
Name: | mcrb_MilestonePaymentsReceived
Namespace Prefix: | mcrb_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Nature of business and basis of presentation. + References No definition available. + Details
Name: | mcrb_NatureOfBusinessAndBasisOfPresentationLineItems
Namespace Prefix: | mcrb_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Amount of cash and cash equivalent. Cash includes, but is not limited to, currency on hand, demand deposit with financial institution, and account with general characteristic of demand deposit. Cash equivalent includes, but is not limited to, short-term, highly liquid investment that is both readily convertible to known amount of cash and so near maturity that it presents insignificant risk of change in value because of change in interest rate. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 230 -SubTopic 10 -Name Accounting Standards Codification -Section 45 -Paragraph 4 -Publisher FASB -URI https://asc.fasb.org/1943274/2147482740/230-10-45-4 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Topic 230 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 8 -Publisher FASB -URI https://asc.fasb.org/1943274/2147482913/230-10-50-8 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Topic 210 -SubTopic 10 -Name Accounting Standards Codification -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02(1)) -Publisher FASB -URI https://asc.fasb.org/1943274/2147480566/210-10-S99-1 Reference 4: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 860 -SubTopic 30 -Name Accounting Standards Codification -Section 50 -Paragraph 1A -Subparagraph (b)(1)(i) -Publisher FASB -URI https://asc.fasb.org/1943274/2147481420/860-30-50-1A Reference 5: http://www.xbrl.org/2003/role/exampleRef -Topic 210 -SubTopic 10 -Name Accounting Standards Codification -Section 45 -Paragraph 1 -Subparagraph (a) -Publisher FASB -URI https://asc.fasb.org/1943274/2147483467/210-10-45-1 + Details
Name: | us-gaap_CashAndCashEquivalentsAtCarryingValue
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition The net result for the period of deducting operating expenses from operating revenues. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 280 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 32 -Subparagraph (f) -Publisher FASB -URI https://asc.fasb.org/1943274/2147482810/280-10-50-32 Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 280 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 30 -Subparagraph (b) -Publisher FASB -URI https://asc.fasb.org/1943274/2147482810/280-10-50-30 Reference 3: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 280 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 22 -Publisher FASB -URI https://asc.fasb.org/1943274/2147482810/280-10-50-22 Reference 4: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 205 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 7 -Publisher FASB -URI https://asc.fasb.org/1943274/2147483499/205-20-50-7 Reference 5: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 323 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 3 -Subparagraph (c) -Publisher FASB -URI https://asc.fasb.org/1943274/2147481687/323-10-50-3 Reference 6: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 205 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 5A -Publisher FASB -URI https://asc.fasb.org/1943274/2147483499/205-20-50-5A Reference 7: http://www.xbrl.org/2003/role/exampleRef -Topic 220 -SubTopic 40 -Name Accounting Standards Codification -Section 55 -Paragraph 4 -Publisher FASB -URI https://asc.fasb.org/1943274/2147476153/220-40-55-4 Reference 8: http://www.xbrl.org/2003/role/exampleRef -Topic 220 -SubTopic 40 -Name Accounting Standards Codification -Section 55 -Paragraph 14 -Publisher FASB -URI https://asc.fasb.org/1943274/2147476153/220-40-55-14 Reference 9: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 270 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 1 -Subparagraph (i) -Publisher FASB -URI https://asc.fasb.org/1943274/2147482964/270-10-50-1 Reference 10: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 280 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 32 -Subparagraph (ee) -Publisher FASB -URI https://asc.fasb.org/1943274/2147482810/280-10-50-32 Reference 11: http://www.xbrl.org/2003/role/exampleRef -Topic 280 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 31 -Publisher FASB -URI https://asc.fasb.org/1943274/2147482810/280-10-50-31 + Details
Name: | us-gaap_OperatingIncomeLoss
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition The number of positions eliminated during the period as a percentage of total positions eliminated during the period in connection with the restructuring plan(s). + References No definition available. + Details
Name: | us-gaap_RestructuringAndRelatedCostNumberOfPositionsEliminatedPeriodPercent
Namespace Prefix: | us-gaap_
Data Type: | dtr-types:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition Amount of expenses associated with exit or disposal activities pursuant to an authorized plan. Excludes expenses related to a discontinued operation or an asset retirement obligation. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Name Accounting Standards Codification -Section 45 -Paragraph 28 -Subparagraph (b) -SubTopic 10 -Topic 230 -Publisher FASB -URI https://asc.fasb.org/1943274/2147482740/230-10-45-28 Reference 2: http://www.xbrl.org/2003/role/exampleRef -Topic 220 -SubTopic 40 -Name Accounting Standards Codification -Section 55 -Paragraph 18 -Publisher FASB -URI https://asc.fasb.org/1943274/2147476153/220-40-55-18 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Topic 420 -SubTopic 10 -Name Accounting Standards Codification -Section S99 -Paragraph 2 -Subparagraph (SAB Topic 5.P.4.b.1) -Publisher FASB -URI https://asc.fasb.org/1943274/2147479823/420-10-S99-2 Reference 4: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 420 -SubTopic 10 -Name Accounting Standards Codification -Section 45 -Paragraph 3 -Publisher FASB -URI https://asc.fasb.org/1943274/2147482047/420-10-45-3 Reference 5: http://www.xbrl.org/2003/role/disclosureRef -Topic 420 -SubTopic 10 -Name Accounting Standards Codification -Section S99 -Paragraph 1 -Subparagraph (SAB Topic 5.P.3) -Publisher FASB -URI https://asc.fasb.org/1943274/2147479823/420-10-S99-1 Reference 6: http://www.xbrl.org/2003/role/disclosureRef -Topic 220 -SubTopic 40 -Name Accounting Standards Codification -Section 50 -Paragraph 21 -Subparagraph (e) -Publisher FASB -URI https://asc.fasb.org/1943274/2147476148/220-40-50-21 Reference 7: http://www.xbrl.org/2003/role/disclosureRef -Topic 220 -SubTopic 40 -Name Accounting Standards Codification -Section 50 -Paragraph 6 -Subparagraph (b) -Publisher FASB -URI https://asc.fasb.org/1943274/2147476148/220-40-50-6 + Details
Name: | us-gaap_RestructuringCharges
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Amount of accumulated undistributed earnings (deficit). + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 505 -SubTopic 10 -Name Accounting Standards Codification -Section S45 -Paragraph 4 -Publisher FASB -URI https://asc.fasb.org/1943274/2147480100/505-10-S45-4 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Topic 942 -SubTopic 210 -Name Accounting Standards Codification -Section S45 -Paragraph 1 -Publisher FASB -URI https://asc.fasb.org/1943274/2147477657/942-210-S45-1 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Topic 942 -SubTopic 210 -Name Accounting Standards Codification -Section S50 -Paragraph 1 -Publisher FASB -URI https://asc.fasb.org/1943274/2147478478/942-210-S50-1 Reference 4: http://www.xbrl.org/2003/role/disclosureRef -Topic 942 -SubTopic 210 -Name Accounting Standards Codification -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-03(21)) -Publisher FASB -URI https://asc.fasb.org/1943274/2147478546/942-210-S99-1 Reference 5: http://www.xbrl.org/2003/role/disclosureRef -Topic 210 -SubTopic 10 -Name Accounting Standards Codification -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02(30)(a)(3)) -Publisher FASB -URI https://asc.fasb.org/1943274/2147480566/210-10-S99-1 Reference 6: http://www.xbrl.org/2003/role/disclosureRef -Topic 210 -SubTopic 10 -Name Accounting Standards Codification -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02(30)(b)) -Publisher FASB -URI https://asc.fasb.org/1943274/2147480566/210-10-S99-1 Reference 7: http://www.xbrl.org/2003/role/exampleRef -Topic 852 -SubTopic 10 -Name Accounting Standards Codification -Section 55 -Paragraph 10 -Publisher FASB -URI https://asc.fasb.org/1943274/2147481372/852-10-55-10 Reference 8: http://www.xbrl.org/2003/role/disclosureRef -Topic 944 -SubTopic 40 -Name Accounting Standards Codification -Section 65 -Paragraph 2 -Subparagraph (g)(2)(i) -Publisher FASB -URI https://asc.fasb.org/1943274/2147480016/944-40-65-2 Reference 9: http://www.xbrl.org/2003/role/disclosureRef -Topic 944 -SubTopic 40 -Name Accounting Standards Codification -Section 65 -Paragraph 2 -Subparagraph (h)(2) -Publisher FASB -URI https://asc.fasb.org/1943274/2147480016/944-40-65-2 Reference 10: http://www.xbrl.org/2003/role/disclosureRef -Topic 946 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 11 -Publisher FASB -URI https://asc.fasb.org/1943274/2147480990/946-20-50-11 Reference 11: http://www.xbrl.org/2003/role/disclosureRef -Topic 944 -SubTopic 210 -Name Accounting Standards Codification -Section S99 -Paragraph 1 -Subparagraph (SX 210.7-03(a)(23)(a)(4)) -Publisher FASB -URI https://asc.fasb.org/1943274/2147478777/944-210-S99-1 Reference 12: http://www.xbrl.org/2003/role/disclosureRef -Topic 946 -SubTopic 210 -Name Accounting Standards Codification -Section S99 -Paragraph 1 -Subparagraph (SX 210.6-04(17)) -Publisher FASB -URI https://asc.fasb.org/1943274/2147479170/946-210-S99-1 + Details
Name: | us-gaap_RetainedEarningsAccumulatedDeficit
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Amount of expenses for special or contractual termination benefits provided to current employees involuntarily terminated under a benefit arrangement associated exit or disposal activities pursuant to an authorized plan. Excludes expenses related to one-time termination benefits, a discontinued operation or an asset retirement obligation. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Name Accounting Standards Codification -Section 45 -Paragraph 28 -Subparagraph (b) -SubTopic 10 -Topic 230 -Publisher FASB -URI https://asc.fasb.org/1943274/2147482740/230-10-45-28 + Details
Name: | us-gaap_SeveranceCosts1
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

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

X
- Details
Name: | us-gaap_RelatedPartyTransactionsByRelatedPartyAxis=mcrb_CombatingAntibioticResistantBacteriaBiopharmaceuticalAcceleratorMember
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: |