INCOME TAXES - Reconciliation of Unrecognized Tax Benefits, Excluding Interest and Penalties (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Unrecognized tax benefits, beginning of period	$ 31,806	$ 12,268	$ 13,271
Additions based on tax positions related to the current year	0	4,014	0
Additions for tax positions of prior years	1,662	16,713	55
Reductions for tax positions of prior years	(263)	0	(211)
Lapse in statute of limitations	(1,394)	(1,189)	(847)
Settlements	(296)	0	0
Unrecognized tax benefits, end of the period	$ 31,515	$ 31,806	$ 12,268