SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Reclassifications Out of Accumulated Other Comprehensive Income) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2025	Jun. 30, 2024	Jun. 30, 2025	Jun. 30, 2024
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning balance	$ 30,937	$ 25,983	$ 30,401	$ 25,292
Unrealized gain on investments	7		14	(1)
Net current period other comprehensive loss	8	0	15	(1)
Ending balance	31,438	26,505	31,438	26,505
Pension Benefits
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Unrealized gain on investments	0		0	0
Amount attributable to tax, before reclassification	0		0	0
Net current period other comprehensive loss	1	0	1	0
Other Benefits
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Unrealized gain on investments	0		0	0
Amount attributable to tax, before reclassification	0		0	0
Net current period other comprehensive loss	0	0	0	0
Available for Sale Securities
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Unrealized gain on investments	7		14	(1)
Amount attributable to tax, before reclassification	3		5	1
Net current period other comprehensive loss	7	0	14	(1)
Accumulated Other Comprehensive Income (Loss)
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning balance	(7)	(9)	(14)	(8)
Ending balance	1	(9)	1	(9)
Accumulated Other Comprehensive Income (Loss) | Pension Benefits
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning balance	(35)	(28)	(35)	(28)
Ending balance	(34)	(28)	(34)	(28)
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) | Available for Sale Securities
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning balance	10	1	3	2
Ending balance	17	1	17	1
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	0
Amortization of prior service cost | Pension Benefits
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Amounts reclassified from other comprehensive income	(1)	0	(1)	(1)
Amount attributable to tax, reclassification	0	0	0	0
Amortization of prior service cost | Other Benefits
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Amounts reclassified from other comprehensive income	1	1	1	1
Amount attributable to tax, reclassification	0	0	0	0
Amortization of prior service cost | Available for Sale Securities
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Amounts reclassified from other comprehensive income	0	0	0	0
Amount attributable to tax, reclassification	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	(3)	(4)	(7)	(8)
Amortization of net actuarial gain | Pension Benefits
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Amounts reclassified from other comprehensive income	1	0	1	0
Amount attributable to tax, reclassification	0	0	0	0
Amortization of net actuarial gain | Other Benefits
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Amounts reclassified from other comprehensive income	(4)	(4)	(8)	(8)
Amount attributable to tax, reclassification	2	2	3	3
Amortization of net actuarial gain | Available for Sale Securities
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Amounts reclassified from other comprehensive income	0	0	0	0
Amount attributable to tax, reclassification	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	8	8
Regulatory account transfer | Pension Benefits
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Amounts reclassified from other comprehensive income	1	0	1	1
Amount attributable to tax, reclassification	0	0	0	0
Regulatory account transfer | Other Benefits
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Amounts reclassified from other comprehensive income	3	3	7	7
Amount attributable to tax, reclassification	2	2	3	3
Regulatory account transfer | Available for Sale Securities
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Amounts reclassified from other comprehensive income	0	0	0	0
Amount attributable to tax, reclassification	$ 0	$ 0	$ 0	$ 0