PENSION AND OTHER POSTRETIREMENT BENEFIT PLANS - Net Pension Plan Assets, by Fair Value Hiearchy (Details) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Non Registered Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 12	$ 10
Qualified and Registered Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	5,502	5,341
Fair Value, Inputs, Level 1 | Non Registered Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	12	10
Fair Value, Inputs, Level 2 | Non Registered Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Fair Value, Inputs, Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	557	455	$ 546
Fair Value, Inputs, Level 3 | Non Registered Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Cash and short-term investments | Non Registered Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	6	5
Cash and short-term investments | Qualified and Registered Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	582	731
Cash and short-term investments | Fair Value, Inputs, Level 1 | Non Registered Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	6	5
Cash and short-term investments | Fair Value, Inputs, Level 1 | Qualified and Registered Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	580	715
Cash and short-term investments | Fair Value, Inputs, Level 2 | Non Registered Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Cash and short-term investments | Fair Value, Inputs, Level 2 | Qualified and Registered Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	2	16
Cash and short-term investments | Fair Value, Inputs, Level 3 | Non Registered Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Cash and short-term investments | Fair Value, Inputs, Level 3 | Qualified and Registered Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Common and preferred stock | Non Registered Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	6	5
Common and preferred stock | Qualified and Registered Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	1	7
Common and preferred stock | Fair Value, Inputs, Level 1 | Non Registered Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	6	5
Common and preferred stock | Fair Value, Inputs, Level 1 | Qualified and Registered Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	1	7
Common and preferred stock | Fair Value, Inputs, Level 2 | Non Registered Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Common and preferred stock | Fair Value, Inputs, Level 2 | Qualified and Registered Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Common and preferred stock | Fair Value, Inputs, Level 3 | Non Registered Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Common and preferred stock | Fair Value, Inputs, Level 3 | Qualified and Registered Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Hedge funds and related investments | Qualified and Registered Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	3,237	3,023
Hedge funds and related investments | Fair Value, Inputs, Level 1 | Qualified and Registered Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	59	62
Hedge funds and related investments | Fair Value, Inputs, Level 2 | Qualified and Registered Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Hedge funds and related investments | Fair Value, Inputs, Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	10	4	3
Hedge funds and related investments | Fair Value, Inputs, Level 3 | Qualified and Registered Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	10	4
Private equity and related investments | Qualified and Registered Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	1,222	1,213
Private equity and related investments | Fair Value, Inputs, Level 1 | Qualified and Registered Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Private equity and related investments | Fair Value, Inputs, Level 2 | Qualified and Registered Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Private equity and related investments | Fair Value, Inputs, Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	102	75	52
Private equity and related investments | Fair Value, Inputs, Level 3 | Qualified and Registered Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	102	75
Derivative financial instruments, assets | Qualified and Registered Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	476	386
Derivative financial instruments, assets | Fair Value, Inputs, Level 1 | Qualified and Registered Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Derivative financial instruments, assets | Fair Value, Inputs, Level 2 | Qualified and Registered Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	31	10
Derivative financial instruments, assets | Fair Value, Inputs, Level 3 | Qualified and Registered Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	445	376
Derivative financial instruments, liabilities | Qualified and Registered Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	(8)
Derivative financial instruments, liabilities | Fair Value, Inputs, Level 1 | Qualified and Registered Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Derivative financial instruments, liabilities | Fair Value, Inputs, Level 2 | Qualified and Registered Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	(8)
Derivative financial instruments, liabilities | Fair Value, Inputs, Level 3 | Qualified and Registered Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Investments | Qualified and Registered Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	5,518	5,352
Investments | Fair Value, Inputs, Level 1 | Qualified and Registered Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	640	784
Investments | Fair Value, Inputs, Level 2 | Qualified and Registered Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	33	18
Investments | Fair Value, Inputs, Level 3 | Qualified and Registered Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	557	455
Accrued liabilities, net | Qualified and Registered Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	(16)	(11)
Pension
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	5,514	5,351	$ 5,491
Net asset value [Member] | Non Registered Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Net asset value [Member] | Cash and short-term investments | Non Registered Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Net asset value [Member] | Cash and short-term investments | Qualified and Registered Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Net asset value [Member] | Common and preferred stock | Non Registered Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Net asset value [Member] | Common and preferred stock | Qualified and Registered Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Net asset value [Member] | Hedge funds and related investments | Qualified and Registered Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	3,168	2,957
Net asset value [Member] | Private equity and related investments | Qualified and Registered Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	1,120	1,138
Net asset value [Member] | Derivative financial instruments, assets | Qualified and Registered Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Net asset value [Member] | Derivative financial instruments, liabilities | Qualified and Registered Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Net asset value [Member] | Investments | Qualified and Registered Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 4,288	$ 4,095