SUBSEQUENT EVENT (Details) (Collateral for debt, USD $) In Millions, unless otherwise specified	Apr. 05, 2012
Collateral for debt
SUBSEQUENT EVENT
Cash outflow for accelerated collateral	$ 50.0
Scheduled original collateral repayment required amount	16.7
Irrevocable letters of credit	25.0
Return of Cash collateral	$ 50.0

The total amount of the contingent obligation under letters of credit outstanding as of the reporting date.

No definition available.

Name:	us-gaap_LettersOfCreditOutstandingAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant