ACCOUNTS RECEIVABLE, NET - Schedule of Allowance for Doubtful Accounts (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Allowance for Doubtful Accounts Receivable [Roll Forward]
Balance at beginning of year	$ 10	$ 10	$ 58
Charges to expense	154	10	17
Charges (credits) to other accounts (deferred revenue)	(56)	0	0
Write-offs	(35)	(10)	(65)
Balance at end of year	$ 73	$ 10	$ 10