SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Reclassifications Out of Accumulated Other Comprehensive Income) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning balance	$ 23,586	$ 21,644	$ 23,075	$ 21,223
Loss on investments		(5)	5	(5)
Net current period other comprehensive gain (loss)	0	(5)	5	(5)
Ending balance	24,015	22,019	24,015	22,019
Pension Benefits
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Amount attributable to tax, before reclassification		0	0	0
Loss on investments		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
Loss on investments		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		2	2	2
Loss on investments		(5)	5	(5)
Net current period other comprehensive gain (loss)	0	(5)	5	(5)
Accumulated Other Comprehensive Income (Loss)
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning balance	5	(15)	0	(15)
Ending balance	5	(20)	5	(20)
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)	0	(6)	0
Ending balance	(1)	(5)	(1)	(5)
Amortization of prior service cost
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Amounts reclassified from other comprehensive income	0	0	0	0
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	0
Amounts reclassified from other comprehensive income	0	(1)	(1)	(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	0	0	0	1
Amounts reclassified from other comprehensive income	0	1	1	2
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	(3)	(6)	(7)	(13)
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	0	1	0	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	1	3	2	6
Amounts reclassified from other comprehensive income	(3)	(7)	(7)	(14)
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	7	13
Regulatory account transfer | Pension Benefits
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Amount attributable to tax, reclassification	1	0	1	0
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	3	2	5
Amounts reclassified from other comprehensive income	3	6	6	12
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