Name:	pl_FinancingReceivableAmountOfNonperformingForeclosedAndRestructuredLoans
Namespace Prefix:	pl_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

Represents the number of categories of loans.

No definition available.

Name:	pl_FinancingReceivableLoanCategoriesNumber
Namespace Prefix:	pl_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

Financing Receivable Not Subject To Pooling And Servicing Agreement, Foreclosed Nonperforming Loan Amount

No definition available.

Name:	pl_FinancingReceivableNotSubjectToPoolingAndServicingAgreementForeclosedNonperformingLoanAmount
Namespace Prefix:	pl_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

Represents the amount of financing receivables not subject to a pooling and servicing agreement that are nonperforming or have been restructured under the terms and conditions of the pooling and service agreement.

No definition available.

Name:	pl_FinancingReceivableNotSubjectToPoolingAndServicingAgreementNonperformingOrRestructuredAmount
Namespace Prefix:	pl_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

Represents the amount of financing receivables subject to a pooling and servicing agreement that are nonperforming or have been restructured under the terms and conditions of the pooling and service agreement.

No definition available.

Name:	pl_FinancingReceivableSubjecttoPoolingandServicingAgreementNonperformingorRestructuredAmount
Namespace Prefix:	pl_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

Represents the principal amount of loans accounted for as troubled debt restructurings satisfied during the period by acceptance or agreement to accept assets.

No definition available.

Name:	pl_MortgageLoansOnRealEstateAccountedForAsTroubledDebtRestructuringsPrincipalAmountSatisfiedByAcceptanceOfAssets
Namespace Prefix:	pl_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

Represents the loan-to-value ratio permitted on commercial mortgage loans in exchange for a participating interest in the cash flows from the underlying property.

No definition available.

Name:	pl_MortgageLoansOnRealEstateLoanToValueRatioParticipatingInterest
Namespace Prefix:	pl_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

Represents the amount of mortgage loans as of the balance sheet date which has a feature providing the entity a participating interest in the cash flows from the underlying real estate.

No definition available.

Name:	pl_MortgageLoansOnRealEstateParticipatingLoans
Namespace Prefix:	pl_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

Represents the amount of assets the entity accepted or agreed to accept on mortgage loans accounted for as troubled debt restructurings during the period which have a feature providing the entity a participating interest in the cash flows from the underlying real estate.

No definition available.

Name:	pl_MortgageLoansOnRealEstateParticipatingLoansAccountedForAsTroubledDebtRestructuringsAssetsAccepted
Namespace Prefix:	pl_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

Represents the amount of income earned during the period on mortgage loans, which have a feature providing the entity a participating interest in the cash flows from the underlying real estate.

No definition available.

Name:	pl_MortgageLoansOnRealEstateParticipatingLoansIncome
Namespace Prefix:	pl_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

Mortgage Loans on Real Estate Participating Loans Accounted for as Troubled Debt Restructurings, Foreclosure Assets Accepted

No definition available.

Name:	pl_MortgageLoansonRealEstateParticipatingLoansAccountedforasTroubledDebtRestructuringsForeclosureAssetsAccepted
Namespace Prefix:	pl_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

Number Of Nonperforming Financing Receivable Subject To Pooling And Servicing Agreement Which Have Been Restructured

No definition available.

Name:	pl_NumberOfNonperformingFinancingReceivableSubjectToPoolingAndServicingAgreementWhichHaveBeenRestructured
Namespace Prefix:	pl_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

A valuation allowance for financing receivables that are expected to be uncollectible.

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

Amount of recovery of financing receivables doubtful of collection that were previously charged off.

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

A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

No definition available.

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

Amount of direct write-downs of financing receivables charged against the allowance.

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

Amount of expense related loan transactions, lease transactions, credit loss from transactions other than loan and lease transactions, and other loss based on assessment of uncollectability from the counterparty to reduce the account to their net realizable value.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 11B
-Subparagraph (c)(2)
-URI http://asc.fasb.org/extlink&oid=84173941&loc=SL6953423-111524

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 225
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-04.11)
-URI http://asc.fasb.org/extlink&oid=6879574&loc=d3e536633-122882

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 28
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=98514028&loc=d3e3602-108585