SCHEDULE II - CONDENSED FINANCIAL INFORMATION OF REGISTRANT (Details 8) (USD $) In Millions, unless otherwise specified	12 Months Ended
Dec. 31, 2012	Dec. 31, 2011
Interest rate floor and reinsurance rate cap agreements
Consideration received for participation in interest rate floor agreement and reinsurance rate cap agreement with Golden Gate II	$ 6.8
Combined liability for interest rate floor and reinsurance rate cap agreements	17.1	6.4
Unrealized gains (losses) on interest rate floor and reinsurance rate cap agreements	$ (10.7)	$ 0.3

Represents the consideration received by the entity for its participation in both an interest rate floor agreement and yearly-renewable-term reinsurance rate cap agreement.

No definition available.

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