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Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	instant

Purchase Commitment, Notice For Optional Extension, Period

No definition available.

Name:	pra_PurchaseCommitmentNoticeForOptionalExtensionPeriod
Namespace Prefix:	pra_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

Return Of Deposit Assets

No definition available.

Name:	pra_ReturnOfDepositAssets
Namespace Prefix:	pra_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

Syndicate Credit Agreement, Auto-Renewal, Period

No definition available.

Name:	pra_SyndicateCreditAgreementAutoRenewalPeriod
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Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

Amount of current lending capacity under the Syndicate credit agreement without considering any amounts currently outstanding under the facility.

No definition available.

Name:	pra_SyndicateCreditAgreementCurrentLendingCapacity
Namespace Prefix:	pra_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

Syndicate Credit Agreement, Interest Rate on Lendings

No definition available.

Name:	pra_SyndicateCreditAgreementInterestRate
Namespace Prefix:	pra_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	instant

Syndicate Credit Agreement, Outstanding Borrowings

No definition available.

Name:	pra_SyndicateCreditAgreementOutstandingBorrowings
Namespace Prefix:	pra_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

For contingent consideration arrangements recognized in connection with a business combination, this element represents an estimate of the high-end of the potential range (undiscounted) of the consideration which may be paid.

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Balance Type:	credit
Period Type:	instant

Amount of liability recognized arising from contingent consideration in a business combination.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
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The carrying amount of the asset transferred to a third party to serve as a deposit, which typically serves as security against failure by the transferor to perform under terms of an agreement.

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

Minimum amount of other commitment not otherwise specified in the taxonomy. Excludes commitments explicitly modeled in the taxonomy, including but not limited to, long-term and short-term purchase commitments, recorded and unrecorded purchase obligations, supply commitments, registration payment arrangements, leases, debt, product warranties, guarantees, environmental remediation obligations, and pensions.

No definition available.

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

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.

No definition available.

Name:	us-gaap_OtherCommitmentsLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

Unused amount of commitments to extend credit to customers.

No definition available.

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

Name:	us-gaap_BusinessAcquisitionAxis=pra_NORCALGroupMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	us-gaap_OtherCommitmentsAxis=pra_FundingCommitmentsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	us-gaap_StatementBusinessSegmentsAxis=pra_LloydsSyndicatesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	us-gaap_StatementBusinessSegmentsAxis=pra_Syndicate1729Member
Namespace Prefix:
Data Type:	na
Balance Type:
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