SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Reclassifications Out of Accumulated Other Comprehensive Income) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning balance	$ 23,075	$ 21,223
Loss on investments	8	(6)
Net current period other comprehensive gain (loss)	(8)	15
Ending balance	25,292	23,075
Pension Benefits
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Amount attributable to tax, before reclassification	0	0
Loss on investments	0	0
Net current period other comprehensive gain (loss)	(16)	21
Other Benefits
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Amount attributable to tax, before reclassification	0	0
Loss on investments	0	0
Net current period other comprehensive gain (loss)	0	0
Customer Credit Trust
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Amount attributable to tax, before reclassification	3	3
Loss on investments	8	(6)
Net current period other comprehensive gain (loss)	8	(6)
Accumulated Other Comprehensive Income (Loss)
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning balance	0	(15)
Ending balance	(8)	0
Accumulated Other Comprehensive Income (Loss) | Pension Benefits
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning balance	(12)	(33)
Ending balance	(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
Ending balance	18	18
Accumulated Other Comprehensive Income (Loss) | Customer Credit Trust
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning balance	(6)	0
Ending balance	2	(6)
Amortization of net actuarial gain (loss)
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Other comprehensive income before reclassifications:	(123)	8
Amounts reclassified from other comprehensive income	(13)	(28)
Amortization of net actuarial gain (loss) | Pension Benefits
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Other comprehensive income before reclassifications, tax	76	102
Other comprehensive income before reclassifications:	(196)	263
Amount attributable to tax, reclassification	0	1
Amounts reclassified from other comprehensive income	1	1
Amortization of net actuarial gain (loss) | Other Benefits
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Other comprehensive income before reclassifications, tax	28	99
Other comprehensive income before reclassifications:	73	(255)
Amount attributable to tax, reclassification	5	11
Amounts reclassified from other comprehensive income	(14)	(29)
Amortization of net actuarial gain (loss) | Customer Credit Trust
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Other comprehensive income before reclassifications, tax	0	0
Other comprehensive income before reclassifications:	0	0
Amount attributable to tax, reclassification	0	0
Amounts reclassified from other comprehensive income	0	0
Regulatory account transfer
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Other comprehensive income before reclassifications:	107	13
Amounts reclassified from other comprehensive income	14	26
Regulatory account transfer | Pension Benefits
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Other comprehensive income before reclassifications, tax	70	94
Other comprehensive income before reclassifications:	180	(242)
Amount attributable to tax, reclassification	1	0
Amounts reclassified from other comprehensive income	2	2
Regulatory account transfer | Other Benefits
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Other comprehensive income before reclassifications, tax	28	99
Other comprehensive income before reclassifications:	(73)	255
Amount attributable to tax, reclassification	4	9
Amounts reclassified from other comprehensive income	12	24
Regulatory account transfer | Customer Credit Trust
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Other comprehensive income before reclassifications, tax	0	0
Other comprehensive income before reclassifications:	0	0
Amount attributable to tax, reclassification	0	0
Amounts reclassified from other comprehensive income	0	0
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
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	1
Amounts reclassified from other comprehensive income	(3)	(3)
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	2
Amounts reclassified from other comprehensive income	2	5
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
Amounts reclassified from other comprehensive income	$ 0	$ 0