INCOME TAXES - Income Tax Contingencies (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
Balance at beginning of the period	$ 36,732	$ 38,372	$ 40,808
Additions based on tax positions related to the current year	10,334	2,050	2,033
Additions for tax positions of prior years	4,716	1,994	2,676
Reductions for tax positions of prior years	(400)	(3,761)	(743)
Settlements	0	0	(5,107)
Expiration of applicable statutes of limitations	(2,507)	(1,923)	(1,295)
Balance at end of the period	$ 48,875	$ 36,732	$ 38,372