SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Fair Value Measurement on Recurring Basis) (Details) - Recurring [Member] - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets fair value, recurring	$ 20,348	$ 16,916
Level 1 [Member] | Mutual Funds [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets fair value, recurring	20,348	6,883
Level 1 [Member] | Equity Funds [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets fair value, recurring	0	10,033
Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets fair value, recurring	1,203	1,705
Level 2 [Member] | Money Market Mutual Fund [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets fair value, recurring	$ 1,203	$ 1,705