v3.26.3
Segment Reporting - Schedule of reportable segment net (loss) income (Detail) - USD ($)
$ in Thousands
 3 Months Ended 9 Months Ended
Sep. 30, 2026
Jun. 30, 2026
Mar. 31, 2026
Sep. 30, 2025
Jun. 30, 2025
Mar. 31, 2025
Sep. 30, 2026
Sep. 30, 2025
Segment Reporting [Line Items]                
Grant revenue $ 593     $ 351     $ 1,687 $ 351
Operating Expenses 16,745     22,828     60,019 74,945
Impairment of long-lived assets 5,705     0     11,512 0
Gain on sale of VOWST Business 0     27,222     25,000 79,588
Net (loss) income (16,286) $ 4,581 $ (19,913) 8,204 $ (19,855) $ 32,682 (31,618) 21,031
Operating Segments [Member]                
Segment Reporting [Line Items]                
Grant revenue 593     351     1,687 351
R&D personnel-related (including stock-based compensation) 2,732     5,229     12,332 17,431
G&A personnel-related (including stock-based compensation) 1,964     3,863     7,926 11,761
Professional fees 1,753     2,035     4,909 7,370
Facility-related and other 1,731     3,578     7,744 12,486
Impairment of long-lived assets 5,705     0     11,512 0
Gain on sale of VOWST Business [1] 0     (27,222)     (25,000) (79,588)
Other segment expense (income) [2] 415     (2,721)     (851) (10,077)
Live Biotherapeutics Platform [Member] | Operating Segments [Member]                
Segment Reporting [Line Items]                
Operating Expenses 2,297     6,165     13,705 17,096
SER-155 [Member] | Operating Segments [Member]                
Segment Reporting [Line Items]                
Operating Expenses $ 282     $ 1,220     $ 1,028 $ 2,841
[1] See Note 3, Discontinued Operations and TSA, for further details.
[2]

[1] Other segment expense (income) includes manufacturing services expenses, research and development expenses on early stage programs, interest income and other expense (income), net.