Name:	pl_FinancingReceivableAmountOfNonperformingForeclosedAndRestructuredLoans
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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

Represents the amount of nonperforming mortgage loans, foreclosed properties and restructured loans pursuant to a pooling and servicing agreement, as a percent of invested assets.

No definition available.

Name:	pl_FinancingReceivableNonperformingForeclosedAndRestructuredLoansToInvestedAssetsPercentage
Namespace Prefix:	pl_
Data Type:	num:percentItemType
Balance Type:	na
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:monetaryItemType
Balance Type:	debit
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 amount of impaired mortgage loans accounted for as troubled debt restructurings as of the balance sheet date, which have a feature providing the entity a participating interest in the cash flows from the underlying real estate.

No definition available.

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

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 have 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:	debit
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
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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

Represents the principal amount of impaired loans accounted for as troubled debt restructurings as of the balance sheet date, which have a feature providing the entity a participating interest in the cash flows from the underlying real estate.

No definition available.

Name:	pl_MortgageLoansOnRealEstatePrincipalAmountOfImpairedLoansAccountedForAsTroubledDebtRestructurings
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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

Represents the number of mortgage loans permanently impaired.

No definition available.

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

Represents the number of nonperforming financing receivables subject to a pooling and servicing agreement, which have been restructured under the terms and conditions of the pooling and servicing agreement.

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.

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)(1)

-URI http://asc.fasb.org/extlink&oid=35738203&loc=SL6953423-111524

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

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

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)(4)

-URI http://asc.fasb.org/extlink&oid=35738203&loc=SL6953423-111524

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

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)(3)

-URI http://asc.fasb.org/extlink&oid=35738203&loc=SL6953423-111524

Name:	us-gaap_FinancingReceivableAllowanceForCreditLossesWriteOffs
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Data Type:	xbrli:monetaryItemType
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Reflects the amount of the write-down related to a troubled debt restructuring.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 310

-SubTopic 40

-Section 50

-Paragraph 4

-URI http://asc.fasb.org/extlink&oid=25495931&loc=d3e18845-111554

Name:	us-gaap_FinancingReceivablesImpairedTroubledDebtRestructuringWriteDown
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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 230

-SubTopic 10

-Section 45

-Paragraph 28

-Subparagraph (a)

-URI http://asc.fasb.org/extlink&oid=31042434&loc=d3e3602-108585

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 04

-Paragraph 11

-Article 9

Reference 3: 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 4: 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=35738203&loc=SL6953423-111524

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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
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