The amount of the monthly facility fee during the final year of the lease term.

No definition available.

Name:	siga_MonthlyFacilityFeeFinalYear
Namespace Prefix:	siga_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

The amount of the monthly facility fee during the second year of the lease term.

+ References

No definition available.

+ Details

Name:	siga_MonthlyFacilityFeeSecondYear
Namespace Prefix:	siga_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

The percentage rate increase to the monthly facility fee per year following the second year of the lease term.

+ References

No definition available.

+ Details

Name:	siga_MonthlyFacilityFeeYearlyRateIncreaseAfterSecondYear
Namespace Prefix:	siga_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

The amount of the monthly rental payments due under the rental agreement entered into after the initial period of the rental agreement.

+ References

No definition available.

+ Details

Name:	siga_MonthlyRentAfterInitialPeriod
Namespace Prefix:	siga_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

The amount of the monthly rental payments due under the rental agreement entered into for the initial period of the rental agreement.

+ References

No definition available.

+ Details

Name:	siga_MonthlyRentDuringInitialPeriod
Namespace Prefix:	siga_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

The length of time of the initial period of the rental agreement in which the fixed monthly payments and other agreements may be different from the remainder of the rental agreement.

+ References

No definition available.

+ Details

Name:	siga_MonthlyRentInitialPeriod
Namespace Prefix:	siga_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount for accounts payable to related parties.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 850
-SubTopic 10
-Section 50
-Paragraph 1
-Subparagraph (d)
-URI http://asc.fasb.org/extlink&oid=6457730&loc=d3e39549-107864

Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08(k)(1))
-URI http://asc.fasb.org/extlink&oid=120395691&loc=d3e23780-122690

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03.15(5))
-URI http://asc.fasb.org/extlink&oid=120398452&loc=d3e534808-122878

Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03.17)
-URI http://asc.fasb.org/extlink&oid=120400017&loc=d3e572229-122910

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Name:	us-gaap_AccountsPayableRelatedPartiesCurrentAndNoncurrent
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Area of a real estate property.

+ References

No definition available.

+ Details

Name:	us-gaap_AreaOfRealEstateProperty
Namespace Prefix:	us-gaap_
Data Type:	dtr-types:areaItemType
Balance Type:	na
Period Type:	instant

- Definition

The amount of expense provided in the period for legal costs incurred on or before the balance sheet date pertaining to resolved, pending or threatened litigation, including arbitration and mediation proceedings.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SX 210.5-03.3)
-URI http://asc.fasb.org/extlink&oid=123367319&loc=SL114868664-224227

+ Details

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

- Definition

Term of lessee's operating lease, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 842
-SubTopic 20
-Section 50
-Paragraph 3
-Subparagraph (a)(3)
-URI http://asc.fasb.org/extlink&oid=123408670&loc=SL77918673-209980

+ Details

Name:	us-gaap_LesseeOperatingLeaseTermOfContract
Namespace Prefix:	us-gaap_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	instant

- Definition

Amount of operating lease expense. Excludes sublease income.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 842
-SubTopic 20
-Section 45
-Paragraph 4
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=123391704&loc=SL77918638-209977

+ Details

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

- Details

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

- Details

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

- Details

Name:	us-gaap_LeaseContractualTermAxis=siga_TheNewHQLeaseMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Note 12 - Related Party Transactions (Details Textual)		3 Months Ended		6 Months Ended
Note 12 - Related Party Transactions (Details Textual)	May 26, 2017 USD ($) ft²	Jun. 30, 2021 USD ($)	Jun. 30, 2020 USD ($)	Jun. 30, 2021 USD ($)	Jun. 30, 2020 USD ($)
Outside Counsel [Member]
Legal Fees		$ 0	$ 200,000	$ 100,000	$ 300,000
Accounts Payable, Related Parties		0		0
MacAndrews and Forbes Incorporated [Member] \| The New HQ Lease [Member]
Lessee, Operating Lease, Term of Contract (Year)	10 years
Area of Real Estate Property (Square Foot) \| ft²	3,200
Monthly Rent During Initial Period	$ 25,333
Monthly Rent, Initial Period (Month)	63 months
Monthly Rent After Initial Period	$ 29,333
Monthly Facility Fee, Second Year	$ 3,333
Monthly Facility Fee, Yearly Rate Increase After Second Year	5.00%
Monthly Facility Fee, Final Year	$ 4,925
Operating Lease, Expense		$ 100,000		$ 200,000