Exercise period of warrants from the date of the Company's initial public offering.

No definition available.

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Namespace Prefix:	bhvn_
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Balance Type:	na
Period Type:	duration

- Definition

Exercise period of warrants from the date of issuance.

+ References

No definition available.

+ Details

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Namespace Prefix:	bhvn_
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Balance Type:	na
Period Type:	duration

- Definition

Value of common shares into which the warrant or right may be converted. For example, the number of common shares issuable upon exercise of the warrant is determined by dividing the value of the shares by the price per share paid by investors.

+ References

No definition available.

+ Details

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Namespace Prefix:	bhvn_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Represents a freestanding financial instrument that is not indexed to the Company's own shares.

+ References

No definition available.

+ Details

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

- Definition

Pertains to the warrants issued to the Guarantor And Co-Guarantor of the Credit Agreement.

+ References

No definition available.

+ Details

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Period Type:	duration

- Definition

Exercise price per share or per unit of warrants or rights outstanding.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08.(i)(4))
-URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e23780-122690

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	num:perShareItemType
Balance Type:	na
Period Type:	instant

- Definition

Number of securities into which the class of warrant or right may be converted. For example, but not limited to, 500,000 warrants may be converted into 1,000,000 shares.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08.(i)(2))
-URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e23780-122690

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	instant

- Definition

Amount of expense (income) related to adjustment to fair value of warrant liability.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 480
-SubTopic 10
-Section 25
-Paragraph 13
-URI http://asc.fasb.org/extlink&oid=6939902&loc=d3e20148-110875

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 28
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=66902209&loc=d3e3602-108585

+ Details

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

- Details

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- Details

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- Details

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- Details

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- Details

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- Details

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Warrants -Guarantor and Co-Guarantor Warrants (Details) - USD ($) $ / shares in Units, $ in Thousands		3 Months Ended
	Jan. 26, 2017	Mar. 31, 2017	Dec. 31, 2016	Aug. 30, 2016
Guarantor and Co-Guarantor Warrants [Abstract]
Fair Value Of Warrant Liabilities		$ 1,234	$ 780
Change in fair value of warrant liability		(454)
Credit Agreement \| Common stock warrants issued in connection with the Credit Agreement \| Common Shares
Guarantor and Co-Guarantor Warrants [Abstract]
Fair Value Of Warrant Liabilities	$ 934	1,234	$ 780	$ 934
Exercise price (in dollars per share)	$ 9.2911
Exercise period from date of issuance	5 years
Exercise period from date of initial public offering	2 years
Credit Agreement \| Common stock warrants issued in connection with the Credit Agreement \| Other income (expense)
Guarantor and Co-Guarantor Warrants [Abstract]
Change in fair value of warrant liability		$ 454
Credit Agreement \| Common stock warrants issued to Guarantor in connection with the Credit Agreement \| Common Shares
Guarantor and Co-Guarantor Warrants [Abstract]
Value of shares into which the warrant may be converted				1,000
Shares that warrant can purchase	107,500
Credit Agreement \| Common stock warrants issued to Co-Guarantor in connection with the Credit Agreement \| Common Shares
Guarantor and Co-Guarantor Warrants [Abstract]
Value of shares into which the warrant may be converted				$ 1,000
Shares that warrant can purchase	107,500