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SIGNIFICANT ACCOUNTING POLICIES (Detail Textuals 3)
 12 Months Ended
Dec. 31, 2017
Schedule of Available-for-sale Securities [Line Items]  
Period of current marketable securities less than 12 months
Period of non-current marketable securities greater than 12 months
Maturity term of non-current marketable securities between 2019 and 2047
Municipal debt obligations | AA- or higher  
Schedule of Available-for-sale Securities [Line Items]  
Period of maturity debt obligations less than one year to over 10 years