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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

The amount of lump sum payment payable to parent.

No definition available.

Name:	btai_LumpSumPaymentToParent
Namespace Prefix:	btai_
Data Type:	xbrli:monetaryItemType
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Period Type:	duration

The period specified for payment.

No definition available.

Name:	btai_MaximumThresholdPeriodForPayment
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Data Type:	xbrli:durationItemType
Balance Type:	na
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Total number of common shares of an entity that have been sold or granted to shareholders (includes common shares that were issued, repurchased and remain in the treasury). These shares represent capital invested by the firm's shareholders and owners, and may be all or only a portion of the number of shares authorized. Shares issued include shares outstanding and shares held in the treasury.

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 http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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The increase (decrease) during the reporting period in the aggregate amount of obligations to be paid to the following types of related parties: a parent company and its subsidiaries; subsidiaries of a common parent; an entity and trust for the benefit of employees, such as pension and profit-sharing trusts that are managed by or under the trusteeship of the entities' management; an entity and its principal owners, management, or member of their immediate families; affiliates; or other parties with the ability to exert significant influence.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 28
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=118932676&loc=d3e3602-108585

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Maximum borrowing capacity under the credit facility without consideration of any current restrictions on the amount that could be borrowed or the amounts currently outstanding under the facility.

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 210.5-02.19(b),22(b))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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Data Type:	xbrli:monetaryItemType
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Period Type:	instant

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.

No definition available.

Name:	us-gaap_RelatedPartyTransactionLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

Name:	srt_CounterpartyNameAxis=btai_BioxcelCorporationMember
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Data Type:	na
Balance Type:
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Name:	us-gaap_TypeOfArrangementAxis=btai_AssetContributionAgreementMember
Namespace Prefix:
Data Type:	na
Balance Type:
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Name:	us-gaap_TypeOfArrangementAxis=us-gaap_CollaborativeArrangementMember
Namespace Prefix:
Data Type:	na
Balance Type:
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Name:	srt_StatementScenarioAxis=btai_LumpSumPayableUponMilestonesMember
Namespace Prefix:
Data Type:	na
Balance Type:
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Name:	srt_StatementScenarioAxis=btai_PayableUponLaterTwelveMonthAnniversaryOfOfferingAndFirstDosingForBxcl501ProgramMember
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