v3.26.3
SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Reclassifications Out of Accumulated Other Comprehensive Income) (Details) - USD ($)
$ in Millions
 3 Months Ended 9 Months Ended
Sep. 30, 2026
Sep. 30, 2025
Sep. 30, 2026
Sep. 30, 2025
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]        
Beginning balance $ 34,153 $ 31,438 $ 32,792 $ 30,401
Unrealized gain (loss) on investments (3) (4) (12) 10
Net current period other comprehensive gain (loss) (2) (4) (10) 11
Ending balance 34,825 32,230 34,825 32,230
Pension Benefits        
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]        
Unrealized 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 1 1
Other Benefits        
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]        
Unrealized 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) 1 0 1 0
Available-for-Sale Securities        
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]        
Unrealized gain (loss) on investments (3) (4) (12) 10
Amount attributable to tax, before reclassification 3 1 7 4
Net current period other comprehensive gain (loss) (3) (4) (12) 10
Accumulated Other Comprehensive Income (Loss)        
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]        
Beginning balance (28) 1 (20) (14)
Ending balance (30) (3) (30) (3)
Accumulated Other Comprehensive Income (Loss) | Pension Benefits        
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]        
Beginning balance (46) (34) (47) (35)
Ending balance (46) (34) (46) (34)
Accumulated Other Comprehensive Income (Loss) | Other Benefits        
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]        
Beginning balance 19 18 19 18
Ending balance 20 18 20 18
Accumulated Other Comprehensive Income (Loss) | Available-for-Sale Securities        
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]        
Beginning balance (1) 17 8 3
Ending balance (4) 13 (4) 13
Amortization of prior service cost (gain)        
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]        
Amounts reclassified from other comprehensive income 1 0 1 0
Amortization of prior service cost (gain) | 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 1 0 1
Amortization of prior service cost (gain) | Other Benefits        
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]        
Amounts reclassified from other comprehensive income 1 0 2 1
Amount attributable to tax, reclassification 0 1 1 1
Amortization of prior service cost (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 1 0 0 0
Amortization of net actuarial loss (gain)        
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]        
Other comprehensive income before reclassifications:     1  
Amounts reclassified from other comprehensive income (3) (4) (7) (11)
Amortization of net actuarial loss (gain) | Pension Benefits        
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]        
Other comprehensive income before reclassifications:     1  
Other comprehensive income before reclassifications, tax     0  
Amounts reclassified from other comprehensive income 0 0 1 1
Amount attributable to tax, reclassification 1 0 1 0
Amortization of net actuarial loss (gain) | Other Benefits        
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]        
Other comprehensive income before reclassifications:     0  
Other comprehensive income before reclassifications, tax     0  
Amounts reclassified from other comprehensive income (3) (4) (8) (12)
Amount attributable to tax, reclassification 1 2 3 5
Amortization of net actuarial loss (gain) | Available-for-Sale Securities        
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]        
Other comprehensive income before reclassifications:     0  
Other comprehensive income before reclassifications, tax     0  
Amounts reclassified from other comprehensive income 0 0 0 0
Amount attributable to tax, reclassification 1 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 4 7 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 0 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 4 7 11
Amount attributable to tax, reclassification 1 1 3 4
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 $ 1 $ 0 $ 0 $ 0