SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Contract assets and liabilities (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Contract assets:
Unbilled receivables	$ 5,437	$ 12,597
Contract liabilities:
Customer advances and unearned income	4,851	6,123
Reserve for audience deficiency	12,779	9,629
Unearned event income	$ 4,864	$ 5,708