Regulatory Assets and Liabilities, Regulatory Liabilities (Details) - USD ($) $ in Millions		Dec. 31, 2021	Dec. 31, 2020
Regulatory Liabilities [Line Items]
Regulatory Liability, Current	[1]	$ 117	$ 123
Regulatory Liability, Noncurrent	[1]	1,927	1,896
Deferred income tax adjustments and TCJA refunds
Regulatory Liabilities [Line Items]
Regulatory Liability, Current	[2]	9	9
Regulatory Liability, Noncurrent	[2]	1,256	1,326
Plant Removal Costs
Regulatory Liabilities [Line Items]
Regulatory Liability, Current		0	0
Regulatory Liability, Noncurrent		613	544
Investment Tax Credit Deferrals
Regulatory Liabilities [Line Items]
Regulatory Liability, Current		0	0
Regulatory Liability, Noncurrent		7	8
Contract Valuation Adjustments
Regulatory Liabilities [Line Items]
Regulatory Liability, Current	[3]	29	12
Regulatory Liability, Noncurrent	[3]	0	0
DOE Settlement
Regulatory Liabilities [Line Items]
Regulatory Liability, Current		14	11
Regulatory Liability, Noncurrent		0	0
Deferred Electric Energy Costs
Regulatory Liabilities [Line Items]
Regulatory Liability, Current		14	8
Regulatory Liability, Noncurrent		0	0
Renewable Resources and Environmental Initiatives
Regulatory Liabilities [Line Items]
Regulatory Liability, Current		1	5
Regulatory Liability, Noncurrent		10	0
Other Regulatory Liabilities
Regulatory Liabilities [Line Items]
Regulatory Liability, Current		50	78
Regulatory Liability, Noncurrent		41	18
Other Current Liabilities
Regulatory Liabilities [Line Items]
Entity's Recorded Provision for Revenue Subject To Refund		$ 15	$ 17

[1] Revenue subject to refund of $15 million and $17 million for 2021 and 2020, respectively, is included in other current liabilities.

[2] Includes the revaluation of recoverable/regulated plant accumulated deferred income taxes and revaluation impact of non-plant accumulated deferred income taxes due to the TCJA.

[3] Includes the fair value of certain long-term PPAs used to meet energy capacity requirements and valuation adjustments on natural gas commodity purchases.