Investments - Mortgage Loan Credit Monitoring (Details) - USD ($) $ in Millions	6 Months Ended	12 Months Ended
Jun. 30, 2024	Dec. 31, 2023	Dec. 31, 2022
Vintage year, Mortgage loans
Mortgage loans, Total amortized cost	$ 19,746.0	$ 19,522.0	$ 19,802.9
Reinsurance recoverable and deposit receivable	23,375.0	24,427.9	21,445.0
Accrued interest receivable	636.4	616.0	575.8
Commercial mortgage loans
Vintage year, Mortgage loans
2024	649.9	1,060.6
2023	1,249.4	1,713.7	1,471.7
2022	1,663.9	2,614.5	2,595.3
2021	2,461.8	1,739.1	1,903.5
2020	1,712.1	2,349.7	2,568.8
2019			2,370.6
Prior	8,663.2	6,622.6	5,333.5
Mortgage loans, Total amortized cost	16,400.3	16,100.2	16,243.4
Accrued interest receivable	63.5	57.1	55.9
Commercial mortgage loans \| A- and above
Vintage year, Mortgage loans
2024	547.3	667.4
2023	815.7	1,214.8	995.9
2022	1,219.2	2,271.5	2,182.5
2021	2,182.3	1,535.8	1,753.8
2020	1,508.8	1,921.0	2,177.2
2019			2,130.8
Prior	6,996.6	5,447.2	4,555.1
Mortgage loans, Total amortized cost	13,269.9	13,057.7	13,795.3
Commercial mortgage loans \| BBB+ thru BBB-
Vintage year, Mortgage loans
2024	85.9	282.6
2023	307.0	356.8	371.8
2022	293.2	343.0	412.8
2021	235.4	203.3	149.7
2020	163.0	309.9	391.6
2019			222.6
Prior	1,059.5	886.9	676.4
Mortgage loans, Total amortized cost	2,144.0	2,382.5	2,224.9
Commercial mortgage loans \| BB+ thru BB-
Vintage year, Mortgage loans
2024	16.7	110.6
2023	126.7	142.1	104.0
2022	151.5
2021	44.1
2020	40.3	35.3
2019			8.9
Prior	239.5	234.6	66.5
Mortgage loans, Total amortized cost	618.8	522.6	179.4
Commercial mortgage loans \| B+ and below
Vintage year, Mortgage loans
2020		83.5
2019			8.3
Prior	367.6	53.9	35.5
Mortgage loans, Total amortized cost	367.6	137.4	43.8
Residential mortgage loans
Vintage year, Mortgage loans
2024	88.4	456.3
2023	402.1	1,025.5	1,109.4
2022	984.9	1,276.5	1,673.8
2021	1,231.8	150.4	366.3
2020	140.1	88.6	100.2
2019			51.8
Prior	314.9	255.9	258.0
Mortgage loans, Total amortized cost	3,162.2	3,253.2	3,559.5
Accrued interest receivable	10.2	10.3	9.8
Residential mortgage loans \| Performing
Vintage year, Mortgage loans
2024	88.4	456.3
2023	400.9	1,023.4	1,101.4
2022	980.3	1,272.5	1,669.1
2021	1,227.9	150.4	364.5
2020	138.9	86.8	99.2
2019			51.2
Prior	311.0	253.6	253.6
Mortgage loans, Total amortized cost	3,147.4	3,243.0	3,539.0
Residential mortgage loans \| Non-performing
Vintage year, Mortgage loans
2023	1.2	2.1	8.0
2022	4.6	4.0	4.7
2021	3.9		1.8
2020	1.2	1.8	1.0
2019			0.6
Prior	3.9	2.3	4.4
Mortgage loans, Total amortized cost	$ 14.8	$ 10.2	20.5
Mortgage loans, delinquent to be considered non-performing (in days)	90 days	90 days
Other loans
Vintage year, Mortgage loans
2024	$ 84.6	$ 168.5
2023	98.8
Prior	0.1	0.1
Mortgage loans, Total amortized cost	183.5	168.6
Accrued interest receivable	1.5	1.6	$ 0.0
Other loans \| Performing
Vintage year, Mortgage loans
2024	84.5	168.5
2023	98.8
Mortgage loans, Total amortized cost	183.3	168.5
Other loans \| Non-performing
Vintage year, Mortgage loans
2024	0.1
Prior	0.1	0.1
Mortgage loans, Total amortized cost	$ 0.2	$ 0.1

The numbers of days for which a mortgage loan has been delinquent such that it is considered non-performing.

No definition available.

Name:	plic_DaysDelinquentNonperforming
Namespace Prefix:	plic_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Amortized cost excluding accrued interest of financing receivable originated five years prior to current fiscal year. Excludes net investment in lease.

+ References

No definition available.

+ Details

Name:	plic_FinancingReceivableExcludingAccruedInterestYearSixOriginatedFiveYearsBeforeCurrentFiscalYear
Namespace Prefix:	plic_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Amortized cost excluding accrued interest, before allowance for credit loss, of financing receivable. Excludes net investment in lease.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 45
-Paragraph 1
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479344/326-20-45-1

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 3B
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479319/326-20-50-3B

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 5
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479319/326-20-50-5

+ Details

Name:	us-gaap_FinancingReceivableExcludingAccruedInterestBeforeAllowanceForCreditLoss
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- References

No definition available.

+ Details

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

- Definition

Amortized cost excluding accrued interest, of financing receivable originated more than five years prior to current fiscal year. Excludes net investment in lease.

+ References

Reference 1: http://www.xbrl.org/2003/role/exampleRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 55
-Paragraph 79
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479294/326-20-55-79

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 6
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479319/326-20-50-6

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 3B
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479319/326-20-50-3B

+ Details

Name:	us-gaap_FinancingReceivableExcludingAccruedInterestOriginatedMoreThanFiveYearsBeforeCurrentFiscalYear
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Amortized cost excluding accrued interest, of financing receivable originated four years prior to current fiscal year. Excludes net investment in lease.

+ References

+ Details

Name:	us-gaap_FinancingReceivableExcludingAccruedInterestYearFiveOriginatedFourYearsBeforeCurrentFiscalYear
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Amortized cost excluding accrued interest, of financing receivable originated three years prior to current fiscal year. Excludes net investment in lease.

+ References

+ Details

Name:	us-gaap_FinancingReceivableExcludingAccruedInterestYearFourOriginatedThreeYearsBeforeCurrentFiscalYear
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Amortized cost excluding accrued interest, of financing receivable originated in current fiscal year. Excludes net investment in lease.

+ References

+ Details

Name:	us-gaap_FinancingReceivableExcludingAccruedInterestYearOneOriginatedCurrentFiscalYear
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Amortized cost excluding accrued interest, of financing receivable originated two years prior to current fiscal year. Excludes net investment in lease.

+ References

+ Details

Name:	us-gaap_FinancingReceivableExcludingAccruedInterestYearThreeOriginatedTwoYearsBeforeCurrentFiscalYear
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Amortized cost excluding accrued interest of financing receivable originated in fiscal year prior to current fiscal year. Excludes net investment in lease.

+ References

+ Details

Name:	us-gaap_FinancingReceivableExcludingAccruedInterestYearTwoOriginatedFiscalYearBeforeCurrentFiscalYear
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Carrying amount as of the balance sheet date of interest earned but not received. Also called accrued interest or accrued interest receivable.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 946
-SubTopic 310
-Name Accounting Standards Codification
-Section 45
-Paragraph 1
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480833/946-310-45-1

Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 210
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(3)(a)(4))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480566/210-10-S99-1

+ Details

Name:	us-gaap_InterestReceivable
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Amount before valuation allowance recoverable under reinsurance contracts. Examples include, but are not limited to, settled and unsettled claims, incurred but not reported losses, loss adjustment expense, premium paid, policy benefits and policy reserves.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 944
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 5
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479838/944-20-50-5

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 944
-SubTopic 210
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03(a)(6))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479440/944-210-S99-1

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 944
-SubTopic 310
-Name Accounting Standards Codification
-Section 45
-Paragraph 5
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479616/944-310-45-5

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 14
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479319/326-20-50-14

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Name Accounting Standards Codification
-Section 50
-Paragraph 7A
-SubTopic 10
-Topic 310
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481962/310-10-50-7A

+ Details

Name:	us-gaap_ReinsuranceRecoverablesGross
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Details

Name:	us-gaap_FinancingReceivablePortfolioSegmentAxis=us-gaap_CommercialRealEstatePortfolioSegmentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_CreditRatingStandardPoorsAxis=plic_StandardPoorsAMinusAndAboveRatingMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_CreditRatingStandardPoorsAxis=plic_StandardPoorsBBBPlusThruBBBMinusRatingMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_CreditRatingStandardPoorsAxis=plic_StandardPoorsBBPlusThruBBMinusRatingMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_CreditRatingStandardPoorsAxis=plic_StandardPoorsBPlusAndBelowRatingMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancingReceivablePortfolioSegmentAxis=us-gaap_ResidentialMortgageMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancialInstrumentPerformanceStatusAxis=plic_PerformingMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancialInstrumentPerformanceStatusAxis=plic_NonperformingMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancingReceivablePortfolioSegmentAxis=us-gaap_ConsumerPortfolioSegmentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: