Regulatory Assets and Liabilities (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2021	Dec. 31, 2020
Schedule of Regulatory Assets and Liabilities [Line Items]
Total Current Regulatory Assets		$ 168	$ 113
Total Non Current Regulatory Assets		$ 834	587
Remaining Amounts of Regulatory Assets for which No Return on Investment During Recovery Period is Provided		5 years
Total regulatory assets		$ 1,002	700
Total Current Regulatory Liabilities		$ 19	48
Remaining Recovery Period of Regulatory Liabilities		1 year
Total Non Current Regulatory Liabilities		$ 1,056	1,058
Total regulatory liabilities		1,075	1,106
Overcollection of Costs [Member]
Schedule of Regulatory Assets and Liabilities [Line Items]
Total Current Regulatory Liabilities		18	47
Deferred Income Tax Charge [Member]
Schedule of Regulatory Assets and Liabilities [Line Items]
Total Non Current Regulatory Liabilities		158	174
Asset Retirement Obligation Costs
Schedule of Regulatory Assets and Liabilities [Line Items]
Total Non Current Regulatory Liabilities		868	863
Other Regulatory Liabilities
Schedule of Regulatory Assets and Liabilities [Line Items]
Total Current Regulatory Liabilities		1	1
Total Non Current Regulatory Liabilities		30	21
El Salvador Tariff Recoveries
Schedule of Regulatory Assets and Liabilities [Line Items]
Total Current Regulatory Assets		80	40
Pension Costs
Schedule of Regulatory Assets and Liabilities [Line Items]
Total Non Current Regulatory Assets	[1]	191	244
Deferred Midwest Independent Service Operator Costs
Schedule of Regulatory Assets and Liabilities [Line Items]
Total Non Current Regulatory Assets		48	61
Environmental Restoration Costs [Member]
Schedule of Regulatory Assets and Liabilities [Line Items]
Total Non Current Regulatory Assets		76	81
Other Regulatory Assets
Schedule of Regulatory Assets and Liabilities [Line Items]
Total Current Regulatory Assets		88	73
Total Non Current Regulatory Assets		135	126
Petersburg Unit Retirement Costs
Schedule of Regulatory Assets and Liabilities [Line Items]
Total Non Current Regulatory Assets		300	75
Deferred Fuel and Purchase Power Costs
Schedule of Regulatory Assets and Liabilities [Line Items]
Total Non Current Regulatory Assets		$ 84	$ 0

[1] Past expenditures on which the Company earns a rate of return.