EMPLOYEE BENEFIT PLANS (Components of Net Periodic Benefit Cost) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Service cost for benefits earned	$ 443	$ 514	$ 472
Interest cost	758	687	714
Expected return on plan assets	(906)	(1,021)	(770)
Amortization of prior service cost	(6)	(6)	(7)
Amortization of net actuarial loss	3	5	22
Net periodic benefit cost	292	179	431
Less: transfer to regulatory account	42	157	(92)
Total expense recognized	334	336	339
PBOP Plans
Defined Benefit Plan Disclosure [Line Items]
Service cost for benefits earned	56	66	59
Interest cost	76	69	77
Expected return on plan assets	(123)	(130)	(97)
Amortization of prior service cost	14	14	15
Amortization of net actuarial loss	(3)	(5)	4
Net periodic benefit cost	$ 20	$ 14	$ 58