Summary of Significant Accounting Policies (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Property, Plant and Equipment [Line Items]
Regulatory Liabilities	$ 1,623	$ 1,466
Remaining Amounts of Regulatory Assets for which No Return on Investment During Recovery Period is Provided	274
Other Investments	$ 150	44
Document Period End Date	Dec. 31, 2022
Letters of Credit Outstanding, Amount	$ 97	$ 18
Public Utilities, Allowance for Funds Used During Construction, Rate	6.50%	6.70%	6.90%
Public Utilities, Allowance for Funds Used During Construction, Capitalized Interest	$ 7	$ 8	$ 8
Public Utilities, Allowance for Funds Used During Construction, Capitalized Cost of Equity	$ 14	$ 17	$ 16
Depreciation expense rate	3.40%	3.40%	3.50%
Amortization of Intangible Assets	$ 58	$ 58	$ 64
Public Utilities, Approved Return on Equity, Percentage	9.50%	9.50%
Regulatory Assets	$ 527	$ 557
Finite-Lived Intangible Assets, Accumulated Amortization	499	446
Future Amortization Expense, Year One	54
Future Amortization Expense, Year Two	49
Future Amortization Expense, Year Three	37
Future Amortization Expense, Year Four	28
Future Amortization Expense, Year Five	23
Power Cost Deadband - Lower Threshold	15
Power Cost Deadband - Upper Threshold	30
Quantifying Misstatement in Current Year Financial Statements, Amount	4,813	4,469
Public Utilities, Property, Plant and Equipment, Accumulated Depreciation	4,423	4,146
Asset Retirement Obligation, Cash Paid to Settle	27	18	18
Deferred Purchased Power Costs	23	62
Unbilled Receivables, Current	131	117
Excise Taxes Collected	53	48	$ 46
Letter of Credit [Member]
Property, Plant and Equipment [Line Items]
Letters of Credit Outstanding, Amount	33
Trojan decommissioning [Member]
Property, Plant and Equipment [Line Items]
Remaining Amounts of Regulatory Assets for which No Return on Investment During Recovery Period is Provided	131	90
Asset Retirement Obligation Costs [Member]
Property, Plant and Equipment [Line Items]
Regulatory Liabilities	7	43
Remaining Amounts of Regulatory Assets for which No Return on Investment During Recovery Period is Provided	0
Deferred Income Tax Charge [Member]
Property, Plant and Equipment [Line Items]
Regulatory Liabilities	194	$ 208
Remaining Amounts of Regulatory Assets for which No Return on Investment During Recovery Period is Provided	$ 0