Fortress Biotech, Inc. Quarterly report pursuant to Section 13 or 15(d)

Sponsored Research Agreements - Additional Information (Detail)

v3.7.0.1

Sponsored Research Agreements - Additional Information (Detail) - USD ($)	1 Months Ended	3 Months Ended
	Feb. 17, 2017	Mar. 31, 2017	Mar. 31, 2016	Dec. 31, 2016	Mar. 31, 2015
Research And Development Expense		$ 8,404,000
Checkpoint Therapeutics, Inc [Member]
Reimbursement Of Cost Recognized As Revenue		200,000	$ 300,000
Helocyte Inc [Member] \| Pep Vax [Member]
Payments For Research And Development Expenses		200,000	1,000,000
Helocyte Inc [Member] \| Triplex [Member]
Payments For Research And Development Expenses		500,000	$ 1,000,000
Mustang Bio, Inc [Member]
Research And Development Expense Payable Milestone Payment		500,000		$ 500,000	$ 2,000,000
City Of Hope [Member] \| AR IL-13 License [Member]
Research And Development Expense		9,238
Payment of Upfront Milestone Fees	$ 9,238
Revenue Recognition Milestone Method Payments Due Over Three Years	200,000
Revenue Recognition Milestone Method Payments Due	100,000
City Of Hope [Member] \| AR CD123 License [Member]
Research And Development Expense		$ 19,450
Payment of Upfront Milestone Fees	19,450
Revenue Recognition Milestone Method Payments Due Over Three Years	200,000
Revenue Recognition Milestone Method Payments Due	$ 100,000

- Definition

The fact represents payment of Upfront Milestone Fees.

+ References

No definition available.

+ Details

Name:	fbio_PaymentOfUpfrontMilestoneFees
Namespace Prefix:	fbio_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

The amount of cash outflow associated research and development expenses paid during the period.

+ References

No definition available.

+ Details

Name:	fbio_PaymentsForResearchAndDevelopmentExpenses
Namespace Prefix:	fbio_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Amount of cost associated with the agreement which is reimbursed by Checkpoint and the company recognized as revenue.

+ References

No definition available.

+ Details

Name:	fbio_ReimbursementOfCostRecognizedAsRevenue
Namespace Prefix:	fbio_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

The amount of research and development expense payable on achieving milestone targets.

+ References

No definition available.

+ Details

Name:	fbio_ResearchAndDevelopmentExpensePayableMilestonePayment
Namespace Prefix:	fbio_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

The fact represents payment of revenue recognition milestone method payments due.

+ References

No definition available.

+ Details

Name:	fbio_RevenueRecognitionMilestoneMethodPaymentsDue
Namespace Prefix:	fbio_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

The fact represents payment of revenue recognition milestone method payments due over next three years.

+ References

No definition available.

+ Details

Name:	fbio_RevenueRecognitionMilestoneMethodPaymentsDueOverThreeYears
Namespace Prefix:	fbio_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
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/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 730
-SubTopic 10
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=6420194&loc=d3e21568-108373

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 985
-SubTopic 20
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=6501960&loc=d3e128462-111756

+ Details

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

- Details

Name:	us-gaap_RelatedPartyTransactionsByRelatedPartyAxis=fbio_CheckpointTherapeuticsIncMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	dei_LegalEntityAxis=fbio_HelocyteIncMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_CapitalizedCostsOfUnprovedPropertiesExcludedFromAmortizationByPropertyOrProjectAxis=fbio_PepVaxMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_CapitalizedCostsOfUnprovedPropertiesExcludedFromAmortizationByPropertyOrProjectAxis=fbio_TriplexMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	dei_LegalEntityAxis=fbio_MustangBioIncMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	dei_LegalEntityAxis=fbio_CityOfHopeMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_IndefiniteLivedIntangibleAssetsByMajorClassAxis=fbio_ArIl13LicenseMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_IndefiniteLivedIntangibleAssetsByMajorClassAxis=fbio_ArCd123LicenseMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: