PENSION AND OTHER POSTRETIREMENT BENEFIT PLANS Components of Net Periodic Benefit Costs (Credits) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Pension
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 8	$ 7	$ 18	$ 17
Interest cost	59	66	119	132
Expected return on plan assets	(100)	(103)	(200)	(205)
Amortization of actuarial loss	52	42	113	97
Amortization of prior service cost	1	1	2	2
Total net periodic benefit cost	20	13	52	43
Other Postretirement Benefits
Defined Benefit Plan Disclosure [Line Items]
Interest cost	1	2	3	4
Amortization of actuarial loss	2	2	4	4
Amortization of prior service cost	(2)	(2)	(4)	(4)
Total net periodic benefit cost	$ 1	$ 2	$ 3	$ 4