PENSION AND OTHER POSTRETIREMENT BENEFIT PLANS Components of Net Periodic Benefit Costs (Credits) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Pension
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 10	$ 10
Interest cost	60	66
Expected return on plan assets	(100)	(102)
Amortization of actuarial loss	61	55
Amortization of prior service cost	1	1
Total net periodic benefit cost	32	30
Other Postretirement Benefits
Defined Benefit Plan Disclosure [Line Items]
Interest cost	2	2
Amortization of actuarial loss	2	2
Amortization of prior service cost	(2)	(2)
Total net periodic benefit cost	$ 2	$ 2