Commitments and Contingencies (Litigation, Regulatory and Environmental Proceedings) (Details) $ in Millions	1 Months Ended					9 Months Ended	12 Months Ended
	Sep. 30, 2022 USD ($)	Jul. 31, 2022 numberOfApplications	Jun. 30, 2022	Jan. 31, 2022 numberOfApplications	Feb. 28, 2021 USD ($)	Sep. 30, 2022 USD ($) claimant numberOfApplications Businesses	Dec. 31, 2023 numberOfApplications	Mar. 31, 2021 USD ($)
Commitments and Contingencies [Line Items]
Loss Contingency, number of plaintiffs | claimant						100
Demand Report Submission Period			90 days
Gas Index Pricing Litigation [Member] | Wisconsin
Commitments and Contingencies [Line Items]
Loss contingency, pending claims, number	1					1
Koch Disputes
Commitments and Contingencies [Line Items]
Amount demanded by plaintiff						$ 286.0
Liability for lawsuit	$ 286.0					$ 286.0
MISO 2015-2016 Planning Resource Auction [Member]
Commitments and Contingencies [Line Items]
Loss contingency, pending claims, number	3					3
Vermilion Facility Old East And North Sites [Member]
Commitments and Contingencies [Line Items]
Site contingency, number of sites with regulatory violations						2
United States Environmental Protection Agency [Member]
Commitments and Contingencies [Line Items]
Cross-State Air Pollution Rule, states revised rule applied beginning 2023 ozone season, number						25
Cross-State Air Pollution Rule, large coal-fueled power plants without Selective Catalytic Reduction controls, percent						20.00%
Clean Air Act, Regional Haze Program, Best Available Retrofit Technology Alternative, Sulfur Dioxide Emissions, number of units in Texas subject to rule, total	39					39
Utility Solid Waste Activities Group, member entities, number | Businesses						130
Illinois Environmental Protection Agency [Member]
Commitments and Contingencies [Line Items]
Coal Combustion Residuals, rules for closure of coal ash ponds in Illinois, number of operating permit applications filed | numberOfApplications						18
Coal Combustion Residuals, rules for closure of coal ash ponds In Illinois, number of construction permit application filed | numberOfApplications		6		3
Illinois Environmental Protection Agency [Member] | Forecast
Commitments and Contingencies [Line Items]
Coal Combustion Residuals, rules for closure of coal ash ponds In Illinois, number of construction permit application filed | numberOfApplications							1
Dynegy Inc. [Member] | MISO 2015-2016 Planning Resource Auction [Member]
Commitments and Contingencies [Line Items]
Loss contingency, pending claims, number	1					1
Electric Reliability Council of Texas [Member]
Commitments and Contingencies [Line Items]
ISO Short-Pay Recovery Process, amount of default ISO can uplift to market participants, maximum amount	$ 2.5
ISO Short-Pay Recovery Process, amount of default ISO can uplift to market participants, recovery period in years	63 years
Electric Reliability Council of Texas [Member] | Brazos Electric Cooperative Inc.
Commitments and Contingencies [Line Items]
ISO Claim for Recovery from Nonaffiliated Counterparty in Bankruptcy	$ 1,900.0
ISO Settlement with Nonaffiliated Counterparty, first payment	600.0
ISO Settlement with Nonaffiliated Counterparty, second payment	554.0
ISO Settlement with Nonaffiliated Counterparty, installment payments, amount per year	$ 13.8
ISO Settlement with Nonaffiliated Counterparty, installment payments, number of years	12 years
ISO Settlement with Non-Affiliated Counterparty, contribution of proceeds from sale of generation assets	$ 117.0
Electric Reliability Council of Texas [Member] | Winter Storm Uri
Commitments and Contingencies [Line Items]
ISO Short-Paid by Nonaffiliated Companies, total					$ 2,900.0
Electric Reliability Council of Texas [Member] | Winter Storm Uri | Default Uplift Liability
Commitments and Contingencies [Line Items]
Liability from Catastrophes, Default Uplift, noncurrent	$ 124.0					$ 124.0		$ 189.0