COMMITMENTS AND CONTINGENCIES (Details) (Indemnification Agreement, USD $) In Millions	Jun. 30, 2011
Indemnification Agreement
Commitments and contingencies
Indemnification agreement with certain officers, maximum	$ 10

Name:

pl_GuarantorObligationsMaximumExposurePerAgreement

Namespace Prefix:

pl

Data Type:

xbrli:monetaryItemType

Balance Type:

debit

Period Type:

instant