SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Summary of Changes in Allowance for Doubtful Accounts) (Details) - USD ($) $ in Thousands	12 Months Ended			24 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2019
Changes in allowance for doubtful accounts against accounts receivables:
Balance at the beginning of the period	$ 10,700
Provision for doubtful accounts	(414)	$ 6,078	$ 2,710
Balance at the ending of the period	15,600	10,700		$ 15,600
Allowance for doubtful accounts
Changes in allowance for doubtful accounts against accounts receivables:
Balance at the beginning of the period	10,664	9,300	7,799	9,300
Provision for doubtful accounts	5,881	6,078	2,710
Write-offs	(900)	(4,714)	(1,209)
Balance at the ending of the period	$ 15,645	$ 10,664	$ 9,300	$ 15,645