XML 35 R29.htm IDEA: XBRL DOCUMENT
v3.24.1.1.u2

Commitments and Contingencies - Additional Information (Details) - USD ($) |  | 3 Months Ended |  |  |
--- | --- | --- | --- | --- | ---
Jan. 08, 2021 | Mar. 31, 2024 | Dec. 31, 2023 | Jul. 01, 2023 | Mar. 31, 2023
Recorded Unconditional Purchase Obligation [Line Items] |  |  |  |  |
Operating leases expiry year |  | 2025 |  |  |
Operating lease right-use-of assets |  | $ 171,000 | $ 202,000 |  |
Pre-clinical Research Study Obligations [Member] |  |  |  |  |
Recorded Unconditional Purchase Obligation [Line Items] |  |  |  |  |
Contractual obligation |  | $ 0 |  |  |
Charlottesville [Member] |  |  |  |  |
Recorded Unconditional Purchase Obligation [Line Items] |  |  |  |  |
Lessee, operating lease, term of contract |  | 12 months |  |  |
Lessee, operating lease, existence of option to extend [true false] |  | true |  |  |
Lessee, operating lease, option to extend |  | The Charlottesville Lease has a term of 12 months and the Company has the ability to renew for three additional one-year periods. |  |  |
Lessee, operating lease, renewal term |  | 1 year |  |  |
Lease liability |  |  |  |  | $ 80,000
Operating lease discount rate |  |  |  | 13.47% | 12.76%
Operating lease right-use-of assets |  |  |  | $ 19,000 |
Piramal Pharma Solutions, Inc. [Member] |  |  |  |  |
Recorded Unconditional Purchase Obligation [Line Items] |  |  |  |  |
Master service agreement date | Jan. 08, 2021 |  |  |  |
Master services agreement initial term | 5 years |  |  |  |
Master services agreement terms, Description |  | The MSA has a term of five years and will automatically renew for successive one-year terms unless either party notifies the other no later than six months prior to the original term or any additional terms of its intention to not renew the MSA. The Company has the right to terminate the MSA for convenience upon thirty days’ prior written notice. |  |  |

X
- Definition Master services agreement date. + References No definition available. + Details
Name: | pstv_MasterServicesAgreementDate
Namespace Prefix: | pstv_
Data Type: | xbrli:dateItemType
Balance Type: | na
Period Type: | duration

X
- Definition Master services agreement initial term. + References No definition available. + Details
Name: | pstv_MasterServicesAgreementInitialTerm
Namespace Prefix: | pstv_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | duration

X
- Definition Master services agreement Terms description. + References No definition available. + Details
Name: | pstv_MasterServicesAgreementTermsDescription
Namespace Prefix: | pstv_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Operating leases, expiry year. + References No definition available. + Details
Name: | pstv_OperatingLeasesExpiryYear
Namespace Prefix: | pstv_
Data Type: | xbrli:gYearItemType
Balance Type: | na
Period Type: | duration

X
- Definition Amount of contractual obligation, including, but not limited to, long-term debt, lease obligation, purchase obligation, and other commitments. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 235 -SubTopic 10 -Name Accounting Standards Codification -Section S99 -Paragraph 3 -Publisher FASB -URI https://asc.fasb.org//1943274/2147480678/235-10-S99-3 + Details
Name: | us-gaap_ContractualObligation
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Discount rate used by lessee to determine present value of operating lease payments. + References Reference 1: http://www.xbrl.org/2003/role/exampleRef -Topic 842 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 3 -Subparagraph (c)(3) -Publisher FASB -URI https://asc.fasb.org//1943274/2147478964/842-20-50-3 + Details
Name: | us-gaap_LesseeOperatingLeaseDiscountRate
Namespace Prefix: | us-gaap_
Data Type: | dtr-types:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition Indicates (true false) whether lessee has option to extend operating lease. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 842 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 3 -Subparagraph (a)(3) -Publisher FASB -URI https://asc.fasb.org//1943274/2147478964/842-20-50-3 + Details
Name: | us-gaap_LesseeOperatingLeaseExistenceOfOptionToExtend
Namespace Prefix: | us-gaap_
Data Type: | xbrli:booleanItemType
Balance Type: | na
Period Type: | duration

X
- Definition Description of terms and conditions of option to extend lessee's operating lease. Includes, but is not limited to, information about option recognized as part of right-of-use asset and lease liability. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 842 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 3 -Subparagraph (a)(3) -Publisher FASB -URI https://asc.fasb.org//1943274/2147478964/842-20-50-3 + Details
Name: | us-gaap_LesseeOperatingLeaseOptionToExtend
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Term of lessee's operating lease renewal, 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 -Topic 842 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 3 -Subparagraph (a)(3) -Publisher FASB -URI https://asc.fasb.org//1943274/2147478964/842-20-50-3 + Details
Name: | us-gaap_LesseeOperatingLeaseRenewalTerm
Namespace Prefix: | us-gaap_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | instant

X
- 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 -Topic 842 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 3 -Subparagraph (a)(3) -Publisher FASB -URI https://asc.fasb.org//1943274/2147478964/842-20-50-3 + Details
Name: | us-gaap_LesseeOperatingLeaseTermOfContract
Namespace Prefix: | us-gaap_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | instant

X
- Definition Present value of lessee's discounted obligation for lease payments from operating lease. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 842 -SubTopic 20 -Name Accounting Standards Codification -Section 45 -Paragraph 1 -Subparagraph (b) -Publisher FASB -URI https://asc.fasb.org//1943274/2147479041/842-20-45-1 + Details
Name: | us-gaap_OperatingLeaseLiability
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Amount of lessee's right to use underlying asset under operating lease. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 842 -SubTopic 20 -Name Accounting Standards Codification -Section 45 -Paragraph 1 -Subparagraph (a) -Publisher FASB -URI https://asc.fasb.org//1943274/2147479041/842-20-45-1 + Details
Name: | us-gaap_OperatingLeaseRightOfUseAsset
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- 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 Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 440 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 6 -Publisher FASB -URI https://asc.fasb.org//1943274/2147482648/440-10-50-6 + Details
Name: | us-gaap_RecordedUnconditionalPurchaseObligationLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Details
Name: | us-gaap_RecordedUnconditionalPurchaseObligationByCategoryOfItemPurchasedAxis=pstv_PreClinicalResearchStudyObligationsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_RelatedPartyTransactionsByRelatedPartyAxis=pstv_CharlottesvilleMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_RelatedPartyTransactionsByRelatedPartyAxis=pstv_PiramalPharmaSolutionsIncMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |