v3.26.1
Balance Sheet Components (Details)
 3 Months Ended 6 Months Ended 12 Months Ended
Jul. 07, 2026
USD ($)
Jul. 02, 2026
USD ($)
Mar. 23, 2026
USD ($)
Loans
Mar. 18, 2026
USD ($)
Jun. 30, 2026
USD ($)
Jun. 30, 2025
USD ($)
Jun. 30, 2026
USD ($)
Jun. 30, 2025
USD ($)
Dec. 31, 2025
USD ($)
Dec. 31, 2024
USD ($)
Mar. 31, 2026
USD ($)
Feb. 28, 2026
Feb. 15, 2026
USD ($)
Jan. 09, 2026
USD ($)
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]                            
Unbilled Receivables, Current         $ 159,000,000   $ 159,000,000   $ 180,000,000          
Accounts Receivable, Allowance for Credit Loss         14,000,000   14,000,000   13,000,000   $ 13,000,000      
Finite-Lived Intangible Assets, Accumulated Amortization         648,000,000   648,000,000   622,000,000          
Amortization of Intangible Assets         21,000,000 $ 19,000,000 42,000,000 $ 38,000,000            
Line of Credit Facility, Current Borrowing Capacity         750,000,000   750,000,000              
Line of Credit Facility, Maximum Borrowing Capacity     $ 1,300,000,000   $ 850,000,000   $ 850,000,000              
Debt Instrument, Covenant Description             65.00%              
Ratio of Indebtedness to Net Capital         0.544   0.544              
Commercial paper, maximum term             270 days              
Short-term debt         $ 0   $ 0              
Line of Credit Facility, Remaining Borrowing Capacity         750,000,000   750,000,000              
Authorized Short-Term Debt         900,000,000   900,000,000              
Proceeds from Issuance of long-term debt             270,000,000 310,000,000            
Long term debt, face amount     $ 700,000,000                      
Number of loans from the Lenders | Loans     4                      
Payments on long-term debt             0 $ 102,000,000            
Letters of Credit Outstanding, Amount         126,000,000   126,000,000              
Line of Credit, Current         320,000,000   320,000,000              
Line of credit facility, amount outstanding         0   0              
Regulatory assets - noncurrent         521,000,000   $ 521,000,000   619,000,000          
Percentage of prudently incurred reliability contingency events cost             80.00%              
Earnings test triggering basis points             0.20%              
Allowed return on equity percentage on deferred storm costs             9.50%              
Earnings test resulted reduction of previously deferred amounts             $ 3,000,000              
Remaining percentage of flowing through operating expenses             20.00%              
Regulatory assets-current         255,000,000   $ 255,000,000   168,000,000          
RCE deferred                 2,000,000 $ 78,000,000        
RCE mechanism docket approved recovery amount in deferred costs       $ 70,000,000                    
RCE mechanism docket approved deferred costs shared at a level of percentage       90.00%                    
Reduction in deferred cost due to recovery request       $ 8,000,000                    
Disallowance of previously deferred costs       2,000,000                    
Reduction in previously deferred costs       10,000,000                    
Equity method investments         21,000,000   21,000,000   19,000,000          
Deferred regulatory asset in balancing account         9,000,000   9,000,000              
PPA [Member]                            
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]                            
Lease term, purchased power agreement                         30 years 20 years
Operating Lease, Liability, Related to Power Purchase Agreements                         $ 331,000,000 $ 612,000,000
PPA [Member] | OPUC [Member]                            
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]                            
Lease term, purchased power agreement                       20 years    
Operating Lease, Liability, Related to Power Purchase Agreements                         $ 636,000,000  
Subsequent Events                            
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]                            
Operations and maintenance expense $ 22,000,000                          
Revolving Credit Facility and Commercial Paper Program [Member]                            
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]                            
Commercial paper         0   0              
Clearwater RAC [Member]                            
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]                            
Deferred regulatory liability in balancing account         9,000,000   9,000,000              
Regulatory Liabilities                   $ 40,000,000        
Additional net regulatory liability                 13,000,000          
Fire                            
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]                            
Regulatory assets - noncurrent         12,000,000   12,000,000   14,000,000          
Regulatory assets-current         5,000,000   5,000,000   5,000,000          
wildfire                            
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]                            
Regulatory assets - noncurrent         0   0   33,000,000          
Regulatory assets-current         45,000,000   45,000,000   9,000,000          
Regulatory assets         45,000,000   45,000,000   42,000,000          
Wildfire Mitigation [Member]                            
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]                            
Operations and maintenance expense             28,000,000              
Deferred regulatory asset         20,000,000   20,000,000              
Deferred regulatory asset in balancing account         16,000,000   16,000,000              
Wildfire Mitigation [Member] | Subsequent Events                            
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]                            
Capital revenue requirement $ 23,000,000                          
StormCosts - Jan 2024                            
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]                            
Regulatory assets - noncurrent         17,000,000   17,000,000   48,000,000          
Regulatory assets-current         25,000,000   25,000,000   0          
Regulatory assets         42,000,000   42,000,000       $ 44,000,000      
StormCosts - RCE                            
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]                            
Regulatory assets - noncurrent         80,000,000   80,000,000              
Storm Recovery Docket | OPUC [Member]                            
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]                            
Disallowance for operating and maintenance costs       $ 1,000,000                    
Portland Harbor Environmental Remediation Account                            
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]                            
Regulatory assets - noncurrent         42,000,000   42,000,000   24,000,000          
Regulatory assets-current         0   0   $ 0          
Environmental Remediation Expense             6,000,000              
Deferred regulatory asset in balancing account         42,000,000   42,000,000              
Reclassification of amounts from other net to environmental remediation             24,000,000              
Term Loan [Member]                            
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]                            
Long term debt, face amount     $ 350,000,000   $ 270,000,000   $ 270,000,000              
Term Loan [Member] | Subsequent Events                            
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]                            
Proceeds from Issuance of long-term debt   $ 80,000,000                        
Term Loan [Member] | SOFR [Member]                            
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]                            
SOFR adjustment rate of basis points applicable margin     1.10%