POSTRETIREMENT BENEFIT PLANS - Amounts Included in Shareowners' Equity, Benefit Plans (Narrative) (Details) - Principal retiree benefit plans - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Estimated amortization of prior service credit in 2018	$ 230
Estimated amortization of net actuarial gain in 2018	80
Amortization of prior service credits	171	$ 164	$ 8
Amortization of net actuarial gain	$ 80	$ 50	$ 25