FAIR VALUE MEASUREMENTS (Fair Value Measurement of Assets on Recurring Basis) (Details) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2013	Dec. 31, 2012	Sep. 30, 2012
Fair Value, Inputs, Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets fair value, recurring	$ 26,059	$ 23,192	$ 21,571
Fair Value, Inputs, Level 1 | Mutual Funds [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets fair value, recurring	14,371	13,349	13,144
Fair Value, Inputs, Level 1 | Equity Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets fair value, recurring	11,688	9,843	8,427
Fair Value, Inputs, Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets fair value, recurring	1,365	2,265	2,229
Fair Value, Inputs, Level 2 | Common/Collective Trust Funds [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets fair value, recurring	$ 1,365	$ 2,265	$ 2,229