SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Reclassifications Out of Accumulated Other Comprehensive Income) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning balance	$ 26,505	$ 24,015	$ 25,292	$ 23,075
Gain (loss) on investments	4	(2)	3	3
Net current period other comprehensive gain (loss)	4	(2)	3	3
Ending balance	27,086	24,384	27,086	24,384
Pension Benefits
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Gain (loss) on investments	0	0	0	0
Amount attributable to tax, before reclassification	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]
Gain (loss) on investments	0	0	0	0
Amount attributable to tax, before reclassification	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]
Gain (loss) on investments	4	(2)	3	3
Amount attributable to tax, before reclassification	2	0	1	2
Net current period other comprehensive gain (loss)	4	(2)	3	3
Accumulated Other Comprehensive Income (Loss)
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning balance	(9)	5	(8)	0
Ending balance	(5)	3	(5)	3
Accumulated Other Comprehensive Income (Loss) | Pension Benefits
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning balance	(28)	(12)	(28)	(12)
Ending balance	(28)	(12)	(28)	(12)
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	(1)	2	(6)
Ending balance	5	(3)	5	(3)
Amortization of prior service cost
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Amounts reclassified from other comprehensive income	0	(1)	0	(1)
Amortization of prior service cost | Pension 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	(1)	(1)	(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	1	1	1
Amounts reclassified from other comprehensive income	1	0	2	1
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 gain
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Amounts reclassified from other comprehensive income	(4)	(2)	(12)	(9)
Amortization of net actuarial gain | 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	1	1	1
Amortization of net actuarial gain | Other Benefits
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Amount attributable to tax, reclassification	2	2	5	4
Amounts reclassified from other comprehensive income	(5)	(3)	(13)	(10)
Amortization of net actuarial gain | 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	4	3	12	10
Regulatory account transfer | Pension Benefits
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Amount attributable to tax, reclassification	0	0	0	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	1	4	3
Amounts reclassified from other comprehensive income	4	3	11	9
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