Agreement, Term From Initial Commercial Sale

No definition available.

Name:	bhvn_AgreementTermFromInitialCommercialSale
Namespace Prefix:	bhvn_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Represents the amount of milestone payment to be paid by the company upon the achievement of specified commercial milestones and annual royalty payments based on net sales of products from patents.

+ References

No definition available.

+ Details

Name:	bhvn_MilestonePaymentToBePaidByCompanyUponSpecifiedCommercialMilestoneAchievement
Namespace Prefix:	bhvn_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- References

No definition available.

+ Details

Name:	bhvn_MilestonePaymentToBePaidByCompanyUponSpecifiedRegulatoryAndCommercialMilestoneAchievement
Namespace Prefix:	bhvn_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Represents the amount of milestone payment to be paid by the company upon the achievement of specified regulatory milestones and annual royalty payments based on net sales of products from patents.

+ References

No definition available.

+ Details

Name:	bhvn_MilestonePaymentToBePaidByCompanyUponSpecifiedRegulatoryMilestoneAchievement
Namespace Prefix:	bhvn_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Represents the amount of milestone payment to be paid by the company upon the achievement of specified regulatory milestones and annual royalty payments based on net sales of products from patents other than the specified product.

+ References

No definition available.

+ Details

Name:	bhvn_MilestonePaymentToBePaidByCompanyUponSpecifiedRegulatoryMilestoneAchievementForOtherThanSpecifiedProducts
Namespace Prefix:	bhvn_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- References

No definition available.

+ Details

Name:	bhvn_MilestonePaymentToBePaidByCompanyUponSpecifiedSalesBasedMilestoneAchievement
Namespace Prefix:	bhvn_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Royalty Payment To Be Paid By Company Upon Specified Approved Products By Net Sales, Percentage

+ References

No definition available.

+ Details

Name:	bhvn_RoyaltyPaymentToBePaidByCompanyUponSpecifiedApprovedProductsByNetSalesPercentage
Namespace Prefix:	bhvn_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration

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

- Definition

The cash outflow to acquire asset without physical form usually arising from contractual or other legal rights, excluding goodwill.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 13
-Subparagraph (c)
-URI https://asc.fasb.org/extlink&oid=126954810&loc=d3e3213-108585

+ Details

Name:	us-gaap_PaymentsToAcquireIntangibleAssets
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

The aggregate costs incurred (1) in a planned search or critical investigation aimed at discovery of new knowledge with the hope that such knowledge will be useful in developing a new product or service, a new process or technique, or in bringing about a significant improvement to an existing product or process; or (2) to translate research findings or other knowledge into a plan or design for a new product or process or for a significant improvement to an existing product or process whether intended for sale or the entity's use, during the reporting period charged to research and development projects, including the costs of developing computer software up to the point in time of achieving technological feasibility, and costs allocated in accounting for a business combination to in-process projects deemed to have no alternative future use.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 912
-SubTopic 730
-Section 25
-Paragraph 1
-URI https://asc.fasb.org/extlink&oid=6472174&loc=d3e58812-109433

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 985
-SubTopic 20
-Section 50
-Paragraph 1
-URI https://asc.fasb.org/extlink&oid=6501960&loc=d3e128462-111756

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 730
-SubTopic 10
-Section 50
-Paragraph 1
-URI https://asc.fasb.org/extlink&oid=6420194&loc=d3e21568-108373

+ Details

Name:	us-gaap_ResearchAndDevelopmentExpense
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Number of shares of stock issued during the period as part of a transaction to acquire assets that do not qualify as a business combination.

+ References

No definition available.

+ Details

Name:	us-gaap_StockIssuedDuringPeriodSharesPurchaseOfAssets
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration

- Definition

Value of shares of stock issued during the period as part of a transaction to acquire assets that do not qualify as a business combination.

+ References

No definition available.

+ Details

Name:	us-gaap_StockIssuedDuringPeriodValuePurchaseOfAssets
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Details

Name:	srt_CounterpartyNameAxis=bhvn_AstraZenecaMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_TypeOfArrangementAxis=us-gaap_CollaborativeArrangementMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_RangeAxis=srt_MaximumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_RangeAxis=srt_MinimumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis=us-gaap_LicensingAgreementsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

License Agreements - AstraZeneca License Agreement (Details) - USD ($)	1 Months Ended		3 Months Ended		9 Months Ended
	Sep. 30, 2018	Oct. 31, 2016	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
License and other agreements
Research and development			$ 52,845,000	$ 46,973,000	$ 300,028,000	$ 139,668,000
AstraZeneca
License and other agreements
Research and development			0	0	0	0
AstraZeneca \| Collaborative arrangement
License and other agreements
Research and development			$ 0	$ 0	$ 0	$ 0
AstraZeneca \| Collaborative arrangement \| Maximum
License and other agreements
Milestone payment to be paid upon regulatory achievement		$ 30,000,000
Milestone payment to be paid for any product other than rimegepant		60,000,000
Commercial milestone payment to be paid		$ 120,000,000
Agreement term after first commercial sale		10 years
Royalty Payment To Be Paid By Company Upon Specified Approved Products By Net Sales, Percentage	10.00%
AstraZeneca \| Collaborative arrangement \| Minimum
License and other agreements
Royalty Payment To Be Paid By Company Upon Specified Approved Products By Net Sales, Percentage	0.00%
AstraZeneca \| License agreement
License and other agreements
Payment for license agreement	$ 3,000,000
Issuance of common shares as payment for assets (in shares)	109,523
Issuance of common shares as payment for assets	$ 4,080,000
Milestone payment due upon achievement of specified regulatory and commercial milestones	55,000,000
Milestone payment due upon achievement of specified sales-based milestones	$ 50,000,000
AstraZeneca \| License agreement \| Maximum
License and other agreements
Royalty Payment To Be Paid By Company Upon Specified Approved Products By Net Sales, Percentage	10.00%
AstraZeneca \| License agreement \| Minimum
License and other agreements
Royalty Payment To Be Paid By Company Upon Specified Approved Products By Net Sales, Percentage	0.00%