Related Party Transactions - Additional Information (Details) - USD ($) $ in Thousands	3 Months Ended
Mar. 31, 2022	Mar. 31, 2021
Third Security, LLC
Related Party Transaction [Line Items]
Expense for services	$ 26	$ 41
Sublease rental income		$ 20
Third Security, LLC \| Executive Chairman
Related Party Transaction [Line Items]
Ownership interest	100.00%

The percentage of ownership of common stock or equity participation in a related party.

No definition available.

Name:	pgen_RelatedPartyOwnershipInterest
Namespace Prefix:	pgen_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Professional and contract service expense includes cost reimbursements for support services related to contracted projects, outsourced management, technical and staff support.

+ References

No definition available.

+ Details

Name:	us-gaap_ProfessionalAndContractServicesExpense
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
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_RelatedPartyTransactionLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of sublease income excluding finance and operating lease expense.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 842
-SubTopic 20
-Section 50
-Paragraph 4
-Subparagraph (e)
-URI http://asc.fasb.org/extlink&oid=123408670&loc=SL77918686-209980

Reference 2: http://www.xbrl.org/2003/role/exampleRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 842
-SubTopic 20
-Section 55
-Paragraph 53
-URI http://asc.fasb.org/extlink&oid=123414884&loc=SL77918982-209971

+ Details

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

- Details

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

- Details

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

- Details

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