FINANCIAL INSTRUMENTS AND FAIR VALUE MEASUREMENTS (Details 3) (Recurring basis, USD $) In Thousands, unless otherwise specified	Mar. 31, 2015	Dec. 31, 2014
Level 1
Assets and liabilities measured at fair value on a recurring basis
Assets	$ 48,102	$ 44,069
Level 1 | Money market funds
Assets and liabilities measured at fair value on a recurring basis
Assets	46,101	41,101
Level 1 | Voluntary Savings Plan - mutual funds held in trust
Assets and liabilities measured at fair value on a recurring basis
Assets	2,001	2,968
Level 2 | Interest rate swap agreement
Assets and liabilities measured at fair value on a recurring basis
Liabilities	$ 1,175	$ 576