SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Components of Net Periodic Benefit Cost) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Service cost for benefits earned	$ 144	$ 147
Interest cost	173	161
Expected return on plan assets	(297)	(261)
Amortization of prior service cost	(1)	(1)
Amortization of net actuarial loss	0	1
Net periodic benefit cost	19	47
Regulatory account transfer	64	37
Net periodic benefit cost	83	84
Other Benefits
Defined Benefit Plan Disclosure [Line Items]
Service cost for benefits earned	15	16
Interest cost	13	13
Expected return on plan assets	(32)	(35)
Amortization of prior service cost	2	4
Amortization of net actuarial loss	(10)	(8)
Net periodic benefit cost	(12)	(10)
Regulatory account transfer	0	0
Net periodic benefit cost	$ (12)	$ (10)