PENSION AND OTHER POSTRETIREMENT BENEFIT PLANS Components of Net Periodic Benefit Costs (Credits) (Details) - USD ($) $ in Millions	3 Months Ended			9 Months Ended
	Sep. 30, 2019	Jun. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Pension
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 8		$ 10	$ 24	$ 28
Interest cost	39		58	122	177
Expected return on plan assets	(54)		(100)	(170)	(300)
Amortization of actuarial loss	27		56	85	169
Amortization of prior service cost (credit)	1		1	3	3
Settlement charge	0	$ (6)	0	449	0
Total net periodic benefit cost	21		25	513	77
Other Postretirement Benefits
Defined Benefit Plan Disclosure [Line Items]
Interest cost	2		2	5	5
Amortization of actuarial loss	1		2	5	6
Amortization of prior service cost (credit)	(1)		(2)	(4)	(6)
Total net periodic benefit cost	$ 2		$ 2	$ 6	$ 5