SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Reclassifications Out of Accumulated Other Comprehensive Income) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2025	Sep. 30, 2024
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning balance	$ 31,438	$ 26,505	$ 30,401	$ 25,292
Unrealized gain (loss) on investments	(4)	4	10	3
Net current period other comprehensive gain (loss)	(4)	4	11	3
Ending balance	32,230	27,086	32,230	27,086
Pension Benefits
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Unrealized gain (loss) on investments	0	0	0
Amount attributable to tax, before reclassification	0	0	0	0
Net current period other comprehensive gain (loss)	0	0	1	0
Other Benefits
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Unrealized gain (loss) on investments	0	0	0
Amount attributable to tax, before reclassification	0	0	0	0
Net current period other comprehensive gain (loss)	0	0	0	0
Available for Sale Securities/Customer Credit Trust
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Unrealized gain (loss) on investments	(4)	4	10	3
Amount attributable to tax, before reclassification	1	2	4	1
Net current period other comprehensive gain (loss)	(4)	4	10	3
Accumulated Other Comprehensive Income (Loss)
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning balance	1	(9)	(14)	(8)
Ending balance	(3)	(5)	(3)	(5)
Accumulated Other Comprehensive Income (Loss) | Pension Benefits
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning balance	(34)	(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/Customer Credit Trust
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning balance	17	1	3	2
Ending balance	13	5	13	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
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	0	(1)	(1)	(2)
Amount attributable to tax, reclassification	1	1	1	1
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	0	1	1	2
Amount attributable to tax, reclassification	1	1	1	1
Amortization of prior service cost | Available for Sale Securities/Customer Credit Trust
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Amounts reclassified from other comprehensive income	0	0	0
Amount attributable to tax, reclassification	0	0	0	0
Amortization of net actuarial loss (gain)
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Amounts reclassified from other comprehensive income	(4)	(4)	(11)	(12)
Amortization of net actuarial loss (gain) | Pension Benefits
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Amounts reclassified from other comprehensive income	0	1	1	1
Amount attributable to tax, reclassification	0	0	0	0
Amortization of net actuarial loss (gain) | Other Benefits
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Amounts reclassified from other comprehensive income	(4)	(5)	(12)	(13)
Amount attributable to tax, reclassification	2	2	5	5
Amortization of net actuarial loss (gain) | Available for Sale Securities/Customer Credit Trust
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Amounts reclassified from other comprehensive income	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	4	12	12
Regulatory account transfer | Pension Benefits
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Amounts reclassified from other comprehensive income	0	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	4	4	11	11
Amount attributable to tax, reclassification	1	1	4	4
Regulatory account transfer | Available for Sale Securities/Customer Credit Trust
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Amounts reclassified from other comprehensive income	0	0	0
Amount attributable to tax, reclassification	$ 0	$ 0	$ 0	$ 0