EMPLOYEE BENEFIT PLANS (Schedule of Fair Value of Plan Assets) (Details) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Defined Benefit Plan Disclosure [Line Items]
Total plan assets at fair value	$ 21,324	$ 17,548
Level 3
Defined Benefit Plan Disclosure [Line Items]
Assets measured at NAV	15	8	$ 4
Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Total plan assets at fair value	18,636	15,284
Assets measured at NAV	18,547	15,312	16,652
Pension Plan | Short-term investments
Defined Benefit Plan Disclosure [Line Items]
Total plan assets at fair value	844	355
Pension Plan | Global equity securities
Defined Benefit Plan Disclosure [Line Items]
Total plan assets at fair value	1,650	1,145
Pension Plan | Absolute Return
Defined Benefit Plan Disclosure [Line Items]
Total plan assets at fair value	1	0
Pension Plan | Real assets
Defined Benefit Plan Disclosure [Line Items]
Total plan assets at fair value	549	461
Pension Plan | Fixed-income securities
Defined Benefit Plan Disclosure [Line Items]
Total plan assets at fair value	8,655	7,121
Pension Plan | Level 1
Defined Benefit Plan Disclosure [Line Items]
Total plan assets at fair value	5,038	3,836
Pension Plan | Level 1 | Short-term investments
Defined Benefit Plan Disclosure [Line Items]
Total plan assets at fair value	613	333
Pension Plan | Level 1 | Global equity securities
Defined Benefit Plan Disclosure [Line Items]
Total plan assets at fair value	1,650	1,145
Pension Plan | Level 1 | Absolute Return
Defined Benefit Plan Disclosure [Line Items]
Total plan assets at fair value	0	0
Pension Plan | Level 1 | Real assets
Defined Benefit Plan Disclosure [Line Items]
Total plan assets at fair value	548	461
Pension Plan | Level 1 | Fixed-income securities
Defined Benefit Plan Disclosure [Line Items]
Total plan assets at fair value	2,227	1,897
Pension Plan | Level 2
Defined Benefit Plan Disclosure [Line Items]
Total plan assets at fair value	6,646	5,238
Pension Plan | Level 2 | Short-term investments
Defined Benefit Plan Disclosure [Line Items]
Total plan assets at fair value	231	22
Pension Plan | Level 2 | Global equity securities
Defined Benefit Plan Disclosure [Line Items]
Total plan assets at fair value	0	0
Pension Plan | Level 2 | Absolute Return
Defined Benefit Plan Disclosure [Line Items]
Total plan assets at fair value	1	0
Pension Plan | Level 2 | Real assets
Defined Benefit Plan Disclosure [Line Items]
Total plan assets at fair value	1	0
Pension Plan | Level 2 | Fixed-income securities
Defined Benefit Plan Disclosure [Line Items]
Total plan assets at fair value	6,413	5,216
Pension Plan | Level 3
Defined Benefit Plan Disclosure [Line Items]
Total plan assets at fair value	15	8
Pension Plan | Level 3 | Short-term investments
Defined Benefit Plan Disclosure [Line Items]
Total plan assets at fair value	0	0
Pension Plan | Level 3 | Global equity securities
Defined Benefit Plan Disclosure [Line Items]
Total plan assets at fair value	0	0
Pension Plan | Level 3 | Absolute Return
Defined Benefit Plan Disclosure [Line Items]
Total plan assets at fair value	0	0
Pension Plan | Level 3 | Real assets
Defined Benefit Plan Disclosure [Line Items]
Total plan assets at fair value	0	0
Pension Plan | Level 3 | Fixed-income securities
Defined Benefit Plan Disclosure [Line Items]
Total plan assets at fair value	15	8
Pension Plan | Assets measured at NAV
Defined Benefit Plan Disclosure [Line Items]
Assets measured at NAV	6,937	6,202
PBOP Plans
Defined Benefit Plan Disclosure [Line Items]
Total plan assets at fair value	2,688	2,264
Assets measured at NAV	2,678	2,258	$ 2,420
PBOP Plans | Short-term investments
Defined Benefit Plan Disclosure [Line Items]
Total plan assets at fair value	37	33
PBOP Plans | Global equity securities
Defined Benefit Plan Disclosure [Line Items]
Total plan assets at fair value	151	115
PBOP Plans | Real assets
Defined Benefit Plan Disclosure [Line Items]
Total plan assets at fair value	58	50
PBOP Plans | Fixed-income securities
Defined Benefit Plan Disclosure [Line Items]
Total plan assets at fair value	1,069	1,010
PBOP Plans | Level 1
Defined Benefit Plan Disclosure [Line Items]
Total plan assets at fair value	439	351
PBOP Plans | Level 1 | Short-term investments
Defined Benefit Plan Disclosure [Line Items]
Total plan assets at fair value	37	33
PBOP Plans | Level 1 | Global equity securities
Defined Benefit Plan Disclosure [Line Items]
Total plan assets at fair value	151	115
PBOP Plans | Level 1 | Real assets
Defined Benefit Plan Disclosure [Line Items]
Total plan assets at fair value	58	50
PBOP Plans | Level 1 | Fixed-income securities
Defined Benefit Plan Disclosure [Line Items]
Total plan assets at fair value	193	153
PBOP Plans | Level 2
Defined Benefit Plan Disclosure [Line Items]
Total plan assets at fair value	875	857
PBOP Plans | Level 2 | Short-term investments
Defined Benefit Plan Disclosure [Line Items]
Total plan assets at fair value	0	0
PBOP Plans | Level 2 | Global equity securities
Defined Benefit Plan Disclosure [Line Items]
Total plan assets at fair value	0	0
PBOP Plans | Level 2 | Real assets
Defined Benefit Plan Disclosure [Line Items]
Total plan assets at fair value	0	0
PBOP Plans | Level 2 | Fixed-income securities
Defined Benefit Plan Disclosure [Line Items]
Total plan assets at fair value	875	857
PBOP Plans | Level 3
Defined Benefit Plan Disclosure [Line Items]
Total plan assets at fair value	1	0
PBOP Plans | Level 3 | Short-term investments
Defined Benefit Plan Disclosure [Line Items]
Total plan assets at fair value	0	0
PBOP Plans | Level 3 | Global equity securities
Defined Benefit Plan Disclosure [Line Items]
Total plan assets at fair value	0	0
PBOP Plans | Level 3 | Real assets
Defined Benefit Plan Disclosure [Line Items]
Total plan assets at fair value	0	0
PBOP Plans | Level 3 | Fixed-income securities
Defined Benefit Plan Disclosure [Line Items]
Total plan assets at fair value	1	0
PBOP Plans | Assets measured at NAV
Defined Benefit Plan Disclosure [Line Items]
Assets measured at NAV	$ 1,373	$ 1,056