SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Reclassifications Out of Accumulated Other Comprehensive Income) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning balance	$ 24,015	$ 22,019	$ 23,075	$ 21,223
Loss on investments	(2)	(12)	3	(17)
Net current period other comprehensive gain (loss)	(2)	(12)	3	(17)
Ending balance	24,384	22,486	24,384	22,486
Pension Benefits
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Amount attributable to tax, before reclassification	0	0	0	0
Loss on investments	0	0	0	0
Net current period other comprehensive gain (loss)	0	0	0	0
Other Benefits
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Amount attributable to tax, before reclassification	0	0	0	0
Loss on investments	0	0	0	0
Net current period other comprehensive gain (loss)	0	0	0	0
Customer Credit Trust
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Amount attributable to tax, before reclassification	0	5	2	7
Loss on investments	(2)	(12)	3	(17)
Net current period other comprehensive gain (loss)	(2)	(12)	3	(17)
Accumulated Other Comprehensive Income (Loss)
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning balance	5	(20)	0	(15)
Ending balance	3	(32)	3	(32)
Accumulated Other Comprehensive Income (Loss) | Pension Benefits
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning balance	(12)	(33)	(12)	(33)
Ending balance	(12)	(33)	(12)	(33)
Accumulated Other Comprehensive Income (Loss) | Other Benefits
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning balance	18	18	18	18
Ending balance	18	18	18	18
Accumulated Other Comprehensive Income (Loss) | Customer Credit Trust
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning balance	(1)	(5)	(6)	0
Ending balance	(3)	(17)	(3)	(17)
Amortization of prior service cost
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Amounts reclassified from other comprehensive income	(1)	2	(1)	2
Amortization of prior service cost | Pension Benefits
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Amount attributable to tax, reclassification	0	1	1	1
Amounts reclassified from other comprehensive income	(1)	0	(2)	(2)
Amortization of prior service cost | Other Benefits
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Amount attributable to tax, reclassification	1	0	1	1
Amounts reclassified from other comprehensive income	0	2	1	4
Amortization of prior service cost | Customer Credit Trust
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Amount attributable to tax, reclassification	0	0	0	0
Amounts reclassified from other comprehensive income	0	0	0	0
Amortization of net actuarial loss
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Amounts reclassified from other comprehensive income	(2)	(8)	(9)	(21)
Amortization of net actuarial loss | Pension Benefits
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Amount attributable to tax, reclassification	0	0	0	0
Amounts reclassified from other comprehensive income	1	0	1	1
Amortization of net actuarial loss | Other Benefits
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Amount attributable to tax, reclassification	2	2	4	8
Amounts reclassified from other comprehensive income	(3)	(8)	(10)	(22)
Amortization of net actuarial loss | Customer Credit Trust
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Amount attributable to tax, reclassification	0	0	0	0
Amounts reclassified from other comprehensive income	0	0	0	0
Regulatory account transfer
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Amounts reclassified from other comprehensive income	3	6	10	19
Regulatory account transfer | Pension Benefits
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Amount attributable to tax, reclassification	0	1	1	1
Amounts reclassified from other comprehensive income	0	0	1	1
Regulatory account transfer | Other Benefits
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Amount attributable to tax, reclassification	1	2	3	7
Amounts reclassified from other comprehensive income	3	6	9	18
Regulatory account transfer | Customer Credit Trust
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Amount attributable to tax, reclassification	0	0	0	0
Amounts reclassified from other comprehensive income	$ 0	$ 0	$ 0	$ 0