EMPLOYEE BENEFIT PLANS - Components of Certain Benefit Costs (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Retirement Benefits [Abstract]
Service cost	$ 2	$ 3	$ 4	$ 6
Interest cost	22	31	45	61
Expected return on assets	(35)	(38)	(74)	(77)
Actuarial (gain) loss	0	0	1	1
Net amortization	27	24	55	48
Net periodic pension expense	$ 16	$ 20	$ 31	$ 39