INCOME TAXES - Income Tax Contingencies (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns
Balance at January 1	$ 2,356	$ 1,548	$ 602
Additions based on tax positions related to the current year	1,325	411	235
Additions for tax positions of prior years	344	397	711
Balance at December 31	$ 4,025	$ 2,356	$ 1,548