Stock-Based Compensation Plans - Stock-Based Awards (Details) - USD ($) shares in Millions, $ in Millions	12 Months Ended
Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Stock-Based Compensation Plans
Stock-Based Compensation Plans - Disclosures
Compensation cost	$ 22.2	$ 25.2	$ 24.4
Related income tax benefit	4.6	4.3	4.0
Capitalized as part of an asset	$ 1.2	$ 1.4	$ 1.5
2014 Stock Incentive Plan, Amended and Restated 2010 Stock Incentive Plan and Stock Incentive Plan
Stock-Based Compensation Plans - Disclosures
Number of shares that will be granted	0

Represents the number of shares (or other type of equity) that will be granted under specified plans.

No definition available.

Name:	plic_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesThatWillBeGranted
Namespace Prefix:	plic_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	instant

- Definition

Represents the compensation cost capitalized during the period arising from share-based compensation arrangements (for example, shares of stock, stock options or other equity instruments) with employees and certain agents.

+ References

No definition available.

+ Details

Name:	plic_ShareBasedCompensationArrangementShareBasedPaymentAwardAmountCapitalized
Namespace Prefix:	plic_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Amount of tax benefit for recognition of expense of award under share-based payment arrangement.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (h)(1)(i)
-URI https://asc.fasb.org/extlink&oid=128089324&loc=d3e5070-113901

+ Details

Name:	us-gaap_EmployeeServiceShareBasedCompensationTaxBenefitFromCompensationExpense
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
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_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of cost expensed and capitalized for award under share-based payment arrangement.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (h)(1)
-URI https://asc.fasb.org/extlink&oid=128089324&loc=d3e5070-113901

+ Details

Name:	us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardCompensationCost1
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Details

Name:	us-gaap_PlanNameAxis=plic_StockBasedCompensationPlansMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_PlanNameAxis=plic_StockBasedCompensationPlans2014StockIncentivePlanAmendedAndRestated2010StockIncentivePlanStockIncentivePlanMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: