ORGANIZATION AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Contract assets and liabilities (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2022	Dec. 31, 2021
Contract assets:
Unbilled receivables	$ 4,557	$ 7,212	$ 10,735
Contract liabilities:
Customer advances and unearned income	5,979	6,934	7,494
Reserve for audience deficiency	4,610	$ 5,505	$ 6,020
Unearned event income	$ 5,735