EMPLOYEE BENEFIT PLANS - Components of Certain Benefit Costs (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Defined Benefit Plan Disclosure [Line Items]
Net periodic pension expense	$ 3	$ 6
Net Periodic Pension Expense
Defined Benefit Plan Disclosure [Line Items]
Service cost	2	2
Interest cost	16	22
Expected return on assets	(37)	(38)
Actuarial (gain) loss	0	0
Net amortization	$ 22	$ 20