FINANCIAL INSTRUMENTS AND FAIR VALUE MEASUREMENTS (Details 2) (Recurring basis, Level 1, USD $) In Thousands, unless otherwise specified	Mar. 31, 2012	Dec. 31, 2011
Financial Assets Measured at Fair Value
Financial Assets at Fair Value	$ 36,702	$ 22,291
Money market funds
Financial Assets Measured at Fair Value
Financial Assets at Fair Value	33,766	18,677
Voluntary Savings Plan - mutual funds held in trust
Financial Assets Measured at Fair Value
Financial Assets at Fair Value	$ 2,936	$ 3,614

This element represents the aggregate of the assets reported on the balance sheet at period end measured at fair value by the entity. This element is intended to be used in connection with the fair value disclosures required in the footnote disclosures to the financial statements.

No definition available.

Name:	us-gaap_AssetsFairValueDisclosure
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant