Regulatory Assets and Liabilities, Regulatory Assets (Details) - USD ($) $ in Millions		Dec. 31, 2024	Dec. 31, 2023
Regulatory Assets [Line Items]
Regulatory Asset, Current		$ 561	$ 611
Regulatory Asset, Noncurrent		2,849	2,798
Regulatory assets not currently earning a return		892	1,085
Pension and retiree medical obligations
Regulatory Assets [Line Items]
Regulatory Asset, Current		39	27
Regulatory Asset, Noncurrent		1,167	1,106
Recoverable deferred taxes on AFUDC recorded in plant
Regulatory Assets [Line Items]
Regulatory Asset, Current		0	0
Regulatory Asset, Noncurrent		368	332
Net AROs
Regulatory Assets [Line Items]
Regulatory Asset, Current		0	0
Regulatory Asset, Noncurrent		387	316
Excess deferred taxes - TCJA
Regulatory Assets [Line Items]
Regulatory Asset, Current		10	10
Regulatory Asset, Noncurrent		184	198
Depreciation differences
Regulatory Assets [Line Items]
Regulatory Asset, Current		17	17
Regulatory Asset, Noncurrent		250	189
Environmental remediation costs
Regulatory Assets [Line Items]
Regulatory Asset, Current		13	15
Regulatory Asset, Noncurrent		39	94
Deferred purchased natural gas and electric energy costs
Regulatory Assets [Line Items]
Regulatory Asset, Current		99	239
Regulatory Asset, Noncurrent		$ 25	80
Deferred purchased natural gas and electric energy costs | Minimum
Regulatory Assets [Line Items]
Regulatory Asset, Remaining Amortization Period		1 year
Deferred purchased natural gas and electric energy costs | Maximum
Regulatory Assets [Line Items]
Regulatory Asset, Remaining Amortization Period		2 years
Conservation programs
Regulatory Assets [Line Items]
Regulatory Asset, Current	[1]	$ 20	19
Regulatory Asset, Noncurrent	[1]	$ 30	54
Conservation programs | Minimum
Regulatory Assets [Line Items]
Regulatory Asset, Remaining Amortization Period		1 year
Conservation programs | Maximum
Regulatory Assets [Line Items]
Regulatory Asset, Remaining Amortization Period		2 years
Purchased power contract costs
Regulatory Assets [Line Items]
Regulatory Asset, Current		$ 5	4
Regulatory Asset, Noncurrent		28	40
PI extended power update
Regulatory Assets [Line Items]
Regulatory Asset, Current		4	4
Regulatory Asset, Noncurrent		$ 34	38
Regulatory Asset, Remaining Amortization Period		10 years
Benson Biomass PPA termination and asset purchase
Regulatory Assets [Line Items]
Regulatory Asset, Current		$ 10	10
Regulatory Asset, Noncurrent		$ 26	36
Regulatory Asset, Remaining Amortization Period		4 years
Sales true-up and revenue decoupling
Regulatory Assets [Line Items]
Regulatory Asset, Current		$ 60	7
Regulatory Asset, Noncurrent		23	33
MISO capacity revenue tracker
Regulatory Assets [Line Items]
Regulatory Asset, Current		63	36
Regulatory Asset, Noncurrent		$ 45	26
MISO capacity revenue tracker | Minimum
Regulatory Assets [Line Items]
Regulatory Asset, Remaining Amortization Period		1 year
MISO capacity revenue tracker | Maximum
Regulatory Assets [Line Items]
Regulatory Asset, Remaining Amortization Period		2 years
Gas pipeline inspection and remediation costs
Regulatory Assets [Line Items]
Regulatory Asset, Current		$ 47	40
Regulatory Asset, Noncurrent		$ 9	25
Gas pipeline inspection and remediation costs | Minimum
Regulatory Assets [Line Items]
Regulatory Liability, Amortization Period		1 year
Gas pipeline inspection and remediation costs | Maximum
Regulatory Assets [Line Items]
Regulatory Liability, Amortization Period		2 years
Nuclear refueling outage costs
Regulatory Assets [Line Items]
Regulatory Asset, Current		$ 51	43
Regulatory Asset, Noncurrent		$ 20	19
Nuclear refueling outage costs | Minimum
Regulatory Assets [Line Items]
Regulatory Asset, Remaining Amortization Period		1 year
Nuclear refueling outage costs | Maximum
Regulatory Assets [Line Items]
Regulatory Asset, Remaining Amortization Period		2 years
Renewable resources and environmental initiatives
Regulatory Assets [Line Items]
Regulatory Asset, Current		$ 34	38
Regulatory Asset, Noncurrent		$ 4	5
Renewable resources and environmental initiatives | Minimum
Regulatory Assets [Line Items]
Regulatory Asset, Remaining Amortization Period		1 year
Renewable resources and environmental initiatives | Maximum
Regulatory Assets [Line Items]
Regulatory Asset, Remaining Amortization Period		2 years
Other
Regulatory Assets [Line Items]
Regulatory Asset, Current		$ 89	102
Regulatory Asset, Noncurrent		$ 210	$ 207

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