v3.25.4

Stockholders' equity - Schedule of warrants or rights (Detail) - $ / shares |  | 6 Months Ended |
--- | --- | --- | ---
Apr. 22, 2024 | Dec. 31, 2025 | Sep. 30, 2025
Class of Warrant or Right [Line Items] |  |  |
Outstanding, beginning of period |  | 20,443,496 |
Pre-funded warrants issued | 5,749,152 |  |
Outstanding, ending of period |  | 20,179,428 |
Weighted Average Exercise Price, beginning of period |  | $ 0.9672 |
Weighted Average Exercise Price, ending of period |  | $ 0.9738 | $ 0.9672
Series 2 Warrants [Member] |  |  |
Class of Warrant or Right [Line Items] |  |  |
Common warrants exercised |  | (63,792) |
Pre-funded warrants exercised |  | $ 1.9299 |
Pre-funded warrants [Member] |  |  |
Class of Warrant or Right [Line Items] |  |  |
Common warrants exercised |  | (200,276) |
Pre-funded warrants exercised |  | $ 0.0001 |

X
- Definition Class of warrant or rights exercised. + References No definition available. + Details
Name: | bntc_ClassOfWarrantOrRightsExercised
Namespace Prefix: | bntc_
Data Type: | xbrli:sharesItemType
Balance Type: | na
Period Type: | duration

X
- Definition Weighted-average exercise price of class of warrants or rights outstanding. + References No definition available. + Details
Name: | bntc_WeightedAverageExercisePriceOfClassOfWarrantsOrRightsOutstanding
Namespace Prefix: | bntc_
Data Type: | dtr-types:perShareItemType
Balance Type: | na
Period Type: | instant

X
- Definition Weighted average exercise price of class of warrants or rights exercised. + References No definition available. + Details
Name: | bntc_Weightedaverageexercisepriceofclassofwarrantsorrightsexercised
Namespace Prefix: | bntc_
Data Type: | dtr-types:perShareItemType
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_ClassOfWarrantOrRightLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
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
- Definition The number of shares issued or sold by the subsidiary or equity method investee per stock transaction. + References No definition available. + Details
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Namespace Prefix: | us-gaap_
Data Type: | xbrli:sharesItemType
Balance Type: | na
Period Type: | duration

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

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