INCOME TAXES - Reconciliation of Beginning and Ending Balances of Gross Unrecognized Tax Benefits (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 [Roll Forward]
Balance at beginning of period	$ 18,157	$ 19,150	$ 22,671
Additions based on tax positions related to the current year	510	978	452
Additions for tax positions of prior years	4,917	174	238
Additions for acquired uncertain tax benefits	0	0	0
Reductions for change in U.S. federal tax rate	0	0	(2,424)
Reductions for tax positions of prior years	(313)	(2,145)	(1,500)
Reductions for a lapse of the applicable statute of limitations	0	0	(287)
Balance at end of period	$ 23,271	$ 18,157	$ 19,150