The expected capacity of new generation development related to the acquisition settlement.

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Costs per kWh of net nuclear generation required to be paid to the Department of Energy per contracts under the Nuclear Waste Policy Act of 1982. Cost can be adjusted prospectively in order to ensure full cost recovery.

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Total number of individual manufactured gas plant sites with associated possible environmental loss contingencies related to remediation.

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Number of individual manufactured gas plant sites where monitoring or remediation activities are occurring.

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Total annual retrospective premium obligation under insurance from an industry mutual insurance company.

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Distribution by a nuclear industry mutual insurance company to its members. This distribution represents excess funds as a result of positive operating experience.

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This represents the maximum total recovery for all losses by all insureds of an industry mutual insurance company in the event of multiple losses by multiple insureds within a twelve-month period.

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This represents the maximum annual retrospective premium obligation that can be assessed to each member by an industry mutual insurance company in the event of a major accidental outage at a power plant incurred by any individual members.

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Annual coverage limit provided by the nuclear insurance arrangement for nuclear incident claims.

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Maximum annual payment of the assessment per nuclear reactor for a nuclear incident, under the financial protection pool mandated by the Price-Anderson Act. This payment is made by each United States nuclear reactor operator over multiple years in the event of an incident at any United States nuclear reactor, until the total assessment has been fully paid.

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Total funds available for nuclear insurance liability claims in a financial protection pool mandated by the Price-Anderson Act.

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Purchase Commitment

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Interest rate used to calculated interest accrued on one-time fee applicable to nuclear generation through April 6, 1983 under the standard contracts with the Department of Energy which was elected to be deferred with interest until just prior to the first delivery of spent nuclear fuel to the Department of Energy. The interest rate used is the 13-week Treasury Rate.

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Recorded amount of the accrual for a material component of an environmental loss contingency.

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Undiscounted amount of the accrual for environmental loss contingencies.

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Percentage of Common Equity Tier One Risk-based Capital to total risk-weighted assets, as defined by regulatory framework.

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Maximum potential amount of future payments (undiscounted) the guarantor could be required to make under the guarantee or each group of similar guarantees before reduction for potential recoveries under recourse or collateralization provisions.

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Carrying amount as of the balance sheet date of reserves for the costs of settling insured claims and costs incurred in the claims settlement process attributable to asbestos and environmental claims, before estimated recoveries from reinsurers.

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Commitments and Contingencies - Narrative (Details)		12 Months Ended
Commitments and Contingencies - Narrative (Details)	Mar. 23, 2016 USD ($) MW	Dec. 31, 2022 MW	Dec. 31, 2019 USD ($) MGPSite Open_claim MW	Dec. 31, 2018 USD ($) MW	Dec. 31, 2017 USD ($) MW	Mar. 31, 2018 USD ($)
Commitments and Contingencies [Line Items]
Guarantor Obligations, Maximum Exposure, Undiscounted			$ 69,000,000
Other Commitment			2,714,000,000
Accrual for Environmental Loss Contingencies, Gross			478,000,000	$ 496,000,000
Environmental loss contingencies			83,000,000
Asbestos Liability Reserve				$ 79,000,000
West Lake [Member]
Commitments and Contingencies [Line Items]
Accrual for Environmental Loss Contingencies, Gross			280,000,000
Exelon Generation Co L L C [Member]
Commitments and Contingencies [Line Items]
Other Commitment			2,110,000,000
Nuclear financial protection pool value			450,000,000
Maximum recovery limit from a nuclear industry mutual insurance company in the event of multiple losses			13,500,000,000
Maximum annual assessment payment mandated by Price-Anderson Act for a nuclear incident			2,900,000,000
Mutual Insurance Total Retrospective Premium Obligation			334,000,000
Mutual Replacement Power Cost Insurance Maximum Retrospective Premium Obligation			3,200,000,000
Cost of spent nuclear fuel disposal per kWh of net nuclear generation			$ 0.001
Spent Nuclear Fuel Treasury Interest Rate			1.551%	1.879%
Accrual for Environmental Loss Contingencies, Gross			$ 105,000,000	$ 108,000,000
Environmental loss contingencies			83,000,000	79,000,000
Exelon Generation Co L L C [Member] \| West Lake [Member]
Commitments and Contingencies [Line Items]
Accrual for Environmental Loss Contingencies, Gross			20,000,000
Environmental loss contingencies			90,000,000
Exelon Generation Co L L C [Member] \| Nuclear Insurance Premiums [Member]
Commitments and Contingencies [Line Items]
Nuclear insurance liability limit per incident			13,900,000,000
Exelon Generation Co L L C [Member] \| Nuclear Insurance Premiums [Member] \| Maximum [Member]
Commitments and Contingencies [Line Items]
Nuclear financial protection pool value			434,000,000
Exelon Generation Co L L C [Member] \| Guarantees Other Than Letters Of Credit and Nuclear Insurance Premiums [Member]
Commitments and Contingencies [Line Items]
Mutual Property Insurance Distribution To Members			136,000,000	58,000,000	$ 60,000,000	$ 31,000,000
Commonwealth Edison Co [Member]
Commitments and Contingencies [Line Items]
Other Commitment			$ 257,000,000
Sites under study/remediation \| MGPSite			21
Accrual for Environmental Loss Contingencies, Gross			$ 304,000,000	329,000,000
PECO Energy Co [Member]
Commitments and Contingencies [Line Items]
Other Commitment			$ 187,000,000
Sites under study/remediation \| MGPSite			8
Accrual for Environmental Loss Contingencies, Gross			$ 19,000,000	27,000,000
Baltimore Gas and Electric Company [Member]
Commitments and Contingencies [Line Items]
Other Commitment			$ 5,000,000
Sites under study/remediation \| MGPSite			4
Accrual for Environmental Loss Contingencies, Gross			$ 2,000,000	5,000,000
Common Equity Tier One Capital Ratio			48.00%
Potomac Electric Power Company [Member]
Commitments and Contingencies [Line Items]
Guarantor Obligations, Maximum Exposure, Undiscounted			$ 23,000,000
Other Commitment			23,000,000
Accrual for Environmental Loss Contingencies, Gross			$ 46,000,000	25,000,000
Common Equity Tier One Capital Ratio			48.00%
Delmarva Power & Light Company [Member]
Commitments and Contingencies [Line Items]
Guarantor Obligations, Maximum Exposure, Undiscounted			$ 29,000,000
Other Commitment			$ 15,000,000
Total number of MGP sites \| MGPSite			1
Accrual for Environmental Loss Contingencies, Gross			$ 1,000,000	1,000,000
Common Equity Tier One Capital Ratio			48.00%
Atlantic City Electric Company [Member]
Commitments and Contingencies [Line Items]
Guarantor Obligations, Maximum Exposure, Undiscounted			$ 18,000,000
Other Commitment			10,000,000
Accrual for Environmental Loss Contingencies, Gross			$ 1,000,000	1,000,000
Common Equity Tier One Capital Ratio			48.00%
Atlantic City Electric Company [Member] \| Minimum [Member]
Commitments and Contingencies [Line Items]
Common Equity Tier One Capital Ratio			30.00%
Pepco Holdings LLC [Member]
Commitments and Contingencies [Line Items]
Guarantor Obligations, Maximum Exposure, Undiscounted			$ 69,000,000
Other Commitment			47,000,000
Accrual for Environmental Loss Contingencies, Gross			48,000,000	$ 27,000,000
PEPCO Holdings Inc [Member]
Commitments and Contingencies [Line Items]
Other Commitment			513,000,000
PEPCO Holdings Inc [Member] \| Potomac Electric Power Company [Member]
Commitments and Contingencies [Line Items]
Other Commitment			120,000,000
PEPCO Holdings Inc [Member] \| Delmarva Power & Light Company [Member]
Commitments and Contingencies [Line Items]
Other Commitment			89,000,000
PEPCO Holdings Inc [Member] \| Atlantic City Electric Company [Member]
Commitments and Contingencies [Line Items]
Other Commitment			111,000,000
PEPCO Holdings Inc [Member] \| Pepco Holdings LLC [Member]
Commitments and Contingencies [Line Items]
Other Commitment			$ 320,000,000
PEPCO Holdings Inc [Member] \| Other Solar Projects [Member]
Commitments and Contingencies [Line Items]
Business Acquisition, Expected New Generation Mwh \| MW	37		27
Other Commitment	$ 127,000,000		$ 120,000,000
PEPCO Holdings Inc [Member] \| Other Solar Projects [Member] \| Exelon Generation Co L L C [Member]
Commitments and Contingencies [Line Items]
Other Commitment			120,000,000
PEPCO Holdings Inc [Member] \| Wind Assets [Member]
Commitments and Contingencies [Line Items]
OtherNonFinancialCommitment1 \| MW	100
PEPCO Holdings Inc [Member] \| Wind Assets [Member] \| Delmarva Power & Light Company [Member]
Commitments and Contingencies [Line Items]
Purchase Commitment \| MW	120			40	40
Subsequent Event [Member] \| PEPCO Holdings Inc [Member] \| Wind Assets [Member] \| Delmarva Power & Light Company [Member]
Commitments and Contingencies [Line Items]
Purchase Commitment \| MW		40
Open Claims [Member] \| Exelon Generation Co L L C [Member]
Commitments and Contingencies [Line Items]
Asbestos Liability Reserve			$ 26,000,000
Open Asbestos Liability Claims \| Open_claim			263
Estimated Future Claims [Member] \| Exelon Generation Co L L C [Member]
Commitments and Contingencies [Line Items]
Asbestos Liability Reserve			$ 57,000,000
Remaining Commitment [Member] \| PEPCO Holdings Inc [Member]
Commitments and Contingencies [Line Items]
Other Commitment			101,000,000
Remaining Commitment [Member] \| PEPCO Holdings Inc [Member] \| Potomac Electric Power Company [Member]
Commitments and Contingencies [Line Items]
Other Commitment			65,000,000
Remaining Commitment [Member] \| PEPCO Holdings Inc [Member] \| Delmarva Power & Light Company [Member]
Commitments and Contingencies [Line Items]
Other Commitment			8,000,000
Remaining Commitment [Member] \| PEPCO Holdings Inc [Member] \| Atlantic City Electric Company [Member]
Commitments and Contingencies [Line Items]
Other Commitment			6,000,000
Remaining Commitment [Member] \| PEPCO Holdings Inc [Member] \| Pepco Holdings LLC [Member]
Commitments and Contingencies [Line Items]
Other Commitment			$ 79,000,000