INCOME TAXES - Reconciliation of the Beginning and Ending Amount of Unrecognized Tax Benefits (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Income Tax Contingency [Line Items]
Balance at beginning of year	$ 6	$ 6
Lapse of statute	(2)	0
Balance at end of year	$ 4	$ 6