v3.26.1
SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Reclassifications Out of Accumulated Other Comprehensive Income) (Details) - USD ($)
$ in Millions
 3 Months Ended 6 Months Ended
Jun. 30, 2026
Jun. 30, 2025
Jun. 30, 2026
Jun. 30, 2025
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]        
Beginning balance $ 33,502 $ 30,937 $ 32,792 $ 30,401
Unrealized gain (loss) on investments (3) 7 (9) 14
Net current period other comprehensive gain (loss) (2) 8 (8) 15
Ending balance 34,153 31,438 34,153 31,438
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) 1 1 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) 0 0 0 0
Available-for-Sale Securities        
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]        
Unrealized gain (loss) on investments (3) 7 (9) 14
Amount attributable to tax, before reclassification 1 3 4 5
Net current period other comprehensive gain (loss) (3) 7 (9) 14
Accumulated Other Comprehensive Income (Loss)        
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]        
Beginning balance (26) (7) (20) (14)
Ending balance (28) 1 (28) 1
Accumulated Other Comprehensive Income (Loss) | Pension Benefits        
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]        
Beginning balance (47) (35) (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 19 18 19 18
Accumulated Other Comprehensive Income (Loss) | Available-for-Sale Securities        
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]        
Beginning balance 2 10 8 3
Ending balance (1) 17 (1) 17
Amortization of prior service cost (gain)        
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 (gain) | Pension 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 (gain) | 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 (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
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 (2) (3) (4) (7)
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 1 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]        
Other comprehensive income before reclassifications:     0  
Other comprehensive income before reclassifications, tax     0  
Amounts reclassified from other comprehensive income (3) (4) (5) (8)
Amount attributable to tax, reclassification 1 2 2 3
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 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 4 4 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 1 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 2 3 4 7
Amount attributable to tax, reclassification 1 2 2 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