COMMITMENTS AND CONTINGENCIES (Details) (USD $) In Millions, unless otherwise specified	Mar. 31, 2014
Indemnification Agreement
Commitments and contingencies
Indemnification agreement with certain officers, maximum	$ 10
IRS proposed adjustment
Commitments and contingencies
Additional income tax cash payments if IRS prevails on every issue	$ 26.6

Additional income tax cash payments required if the entity's appeal to the IRS is denied relating to IRS proposed adjustments to the entity's taxable income for prior years.

No definition available.

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