SUBSEQUENT EVENTS (Details) (Subsequent event, Golden Gate V and Red Mountain, USD $) In Millions, unless otherwise specified	0 Months Ended
Oct. 10, 2012
Subsequent event \| Golden Gate V and Red Mountain
SUBSEQUENT EVENTS
Term of transaction	20 years
Maximum financing capacity under transaction	$ 945
Principal amount of note issued	275
Estimated average annual expense	$ 4.9

Represents the principal amount of note to be issued by one entity to another entity under intra-entity transactions between entities under common control

No definition available.

Name:	pl_IntraEntityTransactionPrincipalAmountOfNoteToBeIssued
Namespace Prefix:	pl_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant