ORGANIZATION AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Details 1) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017	Mar. 31, 2017
Contract assets:
Unbilled receivables	$ 6,284	$ 4,850	$ 7,639
Contract liabilities:
Customer advances and unearned income	4,516	3,372	3,712
Unearned event income	$ 6,157	$ 4,117	$ 7,023