DERIVATIVES - Schedule of Fair Value Hedges (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Derivative Instruments, Gain (Loss) [Line Items]
Derivative	$ 205	$ 66	$ 65
Hedge of interest rate risk | Other Income
Derivative Instruments, Gain (Loss) [Line Items]
Derivative	8	(26)	(6)
Hedged Item	(9)	27	5
Hedge Ineffectiveness	$ (1)	$ 1	$ (1)