Regulatory Assets and Liabilities, Regulatory Assets (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2021	Dec. 31, 2020
Regulatory Assets [Line Items]
Regulatory Asset, Current		$ 353	$ 121
Regulatory Asset, Noncurrent		1,293	1,059
Regulatory assets not currently earning a return		639	195
Pension and Retiree Medical Obligations
Regulatory Assets [Line Items]
Regulatory Asset, Current		26	28
Regulatory Asset, Noncurrent		331	478
Recoverable Purchased Natural Gas and Electric Energy Costs
Regulatory Assets [Line Items]
Regulatory Asset, Current		218	6
Regulatory Asset, Noncurrent		$ 320	0
Recoverable Purchased Natural Gas and Electric Energy Costs | Minimum
Regulatory Assets [Line Items]
Regulatory Asset, Amortization Period		3 years
Recoverable Purchased Natural Gas and Electric Energy Costs | Maximum
Regulatory Assets [Line Items]
Regulatory Asset, Amortization Period		1 year
Depreciation differences
Regulatory Assets [Line Items]
Regulatory Asset, Current		$ 16	16
Regulatory Asset, Noncurrent		$ 173	154
Depreciation differences | Minimum
Regulatory Assets [Line Items]
Regulatory Asset, Amortization Period		1 year
Depreciation differences | Maximum
Regulatory Assets [Line Items]
Regulatory Asset, Amortization Period		10 years
Net AROs
Regulatory Assets [Line Items]
Regulatory Asset, Current	[1]	$ 0	0
Regulatory Asset, Noncurrent	[1]	154	132
Recoverable Deferred Taxes on AFUDC Recorded in Plant
Regulatory Assets [Line Items]
Regulatory Asset, Current		0	0
Regulatory Asset, Noncurrent		116	110
Excess deferred taxes - TCJA
Regulatory Assets [Line Items]
Regulatory Asset, Current		2	3
Regulatory Asset, Noncurrent		56	56
Purchased Power Agreements
Regulatory Assets [Line Items]
Regulatory Asset, Current		3	3
Regulatory Asset, Noncurrent		19	22
Property Tax
Regulatory Assets [Line Items]
Regulatory Asset, Current		16	16
Regulatory Asset, Noncurrent		16	21
Gas pipeline inspection costs
Regulatory Assets [Line Items]
Regulatory Asset, Current		0	0
Regulatory Asset, Noncurrent		$ 12	9
Gas pipeline inspection costs | Minimum
Regulatory Assets [Line Items]
Regulatory Asset, Amortization Period		1 year
Gas pipeline inspection costs | Maximum
Regulatory Assets [Line Items]
Regulatory Asset, Amortization Period		2 years
Conservation programs
Regulatory Assets [Line Items]
Regulatory Asset, Current	[2]	$ 11	11
Regulatory Asset, Noncurrent	[2]	$ 11	11
Conservation programs | Minimum
Regulatory Assets [Line Items]
Regulatory Asset, Amortization Period		1 year
Conservation programs | Maximum
Regulatory Assets [Line Items]
Regulatory Asset, Amortization Period		2 years
Losses on Reacquired Debt
Regulatory Assets [Line Items]
Regulatory Asset, Current		$ 1	1
Regulatory Asset, Noncurrent		2	3
Contract Valuation Adjustments
Regulatory Assets [Line Items]
Regulatory Asset, Current	[3]	3	6
Regulatory Asset, Noncurrent	[3]	0	0
Other
Regulatory Assets [Line Items]
Regulatory Asset, Current		57	31
Regulatory Asset, Noncurrent		$ 83	$ 63

[1] Includes amounts recorded for future recovery of AROs.

[2] Includes costs for conservation programs, as well as incentives allowed in certain jurisdictions.

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