Regulatory Matters- Narrative (Details)					1 Months Ended	3 Months Ended										7 Months Ended	12 Months Ended				36 Months Ended	48 Months Ended		60 Months Ended	72 Months Ended
Regulatory Matters- Narrative (Details)	Dec. 05, 2019 USD ($)	Nov. 26, 2019 USD ($)	May 23, 2019	Jun. 27, 2017 USD ($)	Apr. 30, 2016 USD ($)	Dec. 31, 2019 USD ($)	Sep. 30, 2019 USD ($)	Jun. 30, 2019 USD ($)	Mar. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)	Sep. 30, 2018 USD ($)	Jun. 30, 2018 USD ($)	Mar. 31, 2018 USD ($)	Sep. 30, 2017 USD ($)	Mar. 31, 2013 USD ($)	Dec. 31, 2017 USD ($)	Dec. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)	Dec. 31, 2024 USD ($)	Jun. 30, 2023 USD ($)	Dec. 31, 2022 USD ($)	Dec. 31, 2023 USD ($)	Jul. 10, 2023 USD ($)	Jul. 21, 2017 USD ($)
Regulatory Matters Additional Narrative Information [Line Items]
Regulatory Liabilities						$ 10,392,000,000				$ 10,203,000,000								$ 10,392,000,000	$ 10,203,000,000
Amount of Impairment to Carrying Amount of Regulatory Assets										35,000,000									35,000,000
Regulatory Assets						9,505,000,000				9,427,000,000								9,505,000,000	9,427,000,000
Payments to Acquire Property, Plant, and Equipment														$ 4,000,000	$ 24,000,000
Accounts Payable, Current						3,560,000,000				3,800,000,000								3,560,000,000	3,800,000,000
Revenues						8,343,000,000	$ 8,929,000,000	$ 7,689,000,000	$ 9,477,000,000	8,812,000,000	$ 9,401,000,000	$ 8,074,000,000	$ 9,691,000,000					34,438,000,000	35,978,000,000	$ 33,558,000,000
PECO Energy Co [Member]
Regulatory Matters Additional Narrative Information [Line Items]
Public Utilities, Approved Equity Capital Structure, Percentage	7.62%
Public Utilities, Requested Equity Capital Structure, Percentage	10.35%			11.00%
Additional basis points for RTO membership incentive	50			50
Regulatory Liabilities						601,000,000				596,000,000								601,000,000	596,000,000
Annual Reconciliation Increase (Decrease)																		8,000,000	(6,000,000)
Regulatory Assets						595,000,000				541,000,000								595,000,000	541,000,000
Payments to Acquire Property, Plant, and Equipment	$ 14,000,000			$ 22,000,000
Accounts Payable, Current						387,000,000				370,000,000								387,000,000	370,000,000
Revenues						766,000,000	778,000,000	655,000,000	900,000,000	765,000,000	757,000,000	653,000,000	866,000,000					$ 3,100,000,000	3,038,000,000	2,870,000,000
Commonwealth Edison Co [Member]
Regulatory Matters Additional Narrative Information [Line Items]
Public Utilities, Approved Equity Capital Structure, Percentage																		8.21%
Public Utilities, Requested Equity Capital Structure, Percentage			6.51%
Additional basis points for RTO membership incentive																		50
Regulatory Liabilities						6,742,000,000				6,343,000,000								$ 6,742,000,000	6,343,000,000
Annual Reconciliation Increase (Decrease)																		(16,000,000)
Amount of Impairment to Carrying Amount of Regulatory Assets										3,000,000									3,000,000
Regulatory Assets						1,761,000,000				1,600,000,000								1,761,000,000	1,600,000,000
Public Utilities, Requested Rate Increase (Decrease), Amount																		21,000,000
Payments to Acquire Property, Plant, and Equipment		$ 50,000,000																53,000,000	(3,000,000)
Accounts Payable, Current						527,000,000				607,000,000								527,000,000	607,000,000
Purchase Obligation																										$ 170,000,000
Revenues						1,405,000,000	1,583,000,000	1,351,000,000	1,408,000,000	1,373,000,000	1,598,000,000	1,398,000,000	1,512,000,000					$ 5,747,000,000	5,882,000,000	5,536,000,000
Baltimore Gas and Electric Company [Member]
Regulatory Matters Additional Narrative Information [Line Items]
Public Utilities, Approved Equity Capital Structure, Percentage																		7.35%
Additional basis points for RTO membership incentive																		50
Regulatory Liabilities						1,228,000,000				1,269,000,000								$ 1,228,000,000	1,269,000,000
Annual Reconciliation Increase (Decrease)																		(23,000,000)
Amount of Impairment to Carrying Amount of Regulatory Assets										5,000,000									5,000,000
Regulatory Assets						637,000,000				575,000,000								637,000,000	575,000,000
Public Utilities, Requested Rate Increase (Decrease), Amount																		(10,000,000)
Accounts Payable, Current						243,000,000				295,000,000								243,000,000	295,000,000
Revenues						779,000,000	703,000,000	649,000,000	976,000,000	799,000,000	731,000,000	662,000,000	977,000,000					3,106,000,000	3,169,000,000	3,176,000,000
Pepco Holdings LLC [Member]
Regulatory Matters Additional Narrative Information [Line Items]
Regulatory Liabilities						1,777,000,000				1,948,000,000								1,777,000,000	1,948,000,000
Amount of Impairment to Carrying Amount of Regulatory Assets										27,000,000									27,000,000
Regulatory Assets						2,473,000,000				2,769,000,000								2,473,000,000	2,769,000,000
Accounts Payable, Current						462,000,000				496,000,000								462,000,000	496,000,000
Revenues						1,107,000,000	1,380,000,000	1,091,000,000	1,228,000,000	1,115,000,000	1,359,000,000	1,074,000,000	1,249,000,000					$ 4,806,000,000	4,798,000,000	4,672,000,000
Potomac Electric Power Company [Member]
Regulatory Matters Additional Narrative Information [Line Items]
Public Utilities, Approved Equity Capital Structure, Percentage																		7.75%
Additional basis points for RTO membership incentive																		50
Regulatory Liabilities						754,000,000				829,000,000								$ 754,000,000	829,000,000
Annual Reconciliation Increase (Decrease)																		11,000,000
Amount of Impairment to Carrying Amount of Regulatory Assets										14,000,000									14,000,000
Regulatory Assets						772,000,000				881,000,000								772,000,000	881,000,000
Public Utilities, Requested Rate Increase (Decrease), Amount																		15,000,000
Accounts Payable, Current						195,000,000				214,000,000								195,000,000	214,000,000
Revenues						513,000,000	642,000,000	531,000,000	575,000,000	529,000,000	626,000,000	521,000,000	555,000,000					$ 2,260,000,000	2,232,000,000	2,151,000,000
Delmarva Power & Light Company [Member]
Regulatory Matters Additional Narrative Information [Line Items]
Public Utilities, Approved Equity Capital Structure, Percentage																		7.14%
Additional basis points for RTO membership incentive																		50
Regulatory Liabilities						611,000,000				665,000,000								$ 611,000,000	665,000,000
Annual Reconciliation Increase (Decrease)																		(1,000,000)
Amount of Impairment to Carrying Amount of Regulatory Assets										6,000,000									6,000,000
Regulatory Assets						274,000,000				290,000,000								274,000,000	290,000,000
Public Utilities, Requested Rate Increase (Decrease), Amount																		17,000,000
Accounts Payable, Current						112,000,000				111,000,000								112,000,000	111,000,000
Revenues						319,000,000	319,000,000	287,000,000	380,000,000	331,000,000	328,000,000	289,000,000	384,000,000					$ 1,306,000,000	1,332,000,000	1,300,000,000
Atlantic City Electric Company [Member]
Regulatory Matters Additional Narrative Information [Line Items]
Public Utilities, Approved Equity Capital Structure, Percentage																		7.79%
Additional basis points for RTO membership incentive																		50
Regulatory Liabilities						382,000,000				420,000,000								$ 382,000,000	420,000,000
Annual Reconciliation Increase (Decrease)																		(2,000,000)
Amount of Impairment to Carrying Amount of Regulatory Assets										7,000,000									7,000,000
Regulatory Assets						425,000,000				426,000,000								425,000,000	426,000,000
Public Utilities, Requested Rate Increase (Decrease), Amount																		11,000,000
Accounts Payable, Current						144,000,000				154,000,000								144,000,000	154,000,000
Revenues						274,000,000	419,000,000	274,000,000	273,000,000	254,000,000	406,000,000	265,000,000	310,000,000					1,240,000,000	1,236,000,000	1,186,000,000
Exelon Generation Co L L C [Member]
Regulatory Matters Additional Narrative Information [Line Items]
Payments to Acquire Property, Plant, and Equipment														$ 4,000,000	$ 24,000,000
Accounts Payable, Current						1,692,000,000				1,847,000,000								1,692,000,000	1,847,000,000
Revenues						4,644,000,000	$ 4,774,000,000	$ 4,210,000,000	$ 5,296,000,000	5,069,000,000	$ 5,278,000,000	$ 4,579,000,000	$ 5,512,000,000					18,924,000,000	20,437,000,000	18,500,000,000
Under/Over Recovered Transmission Costs [Member]
Regulatory Matters Additional Narrative Information [Line Items]
Regulatory Assets						11,000,000				41,000,000								11,000,000	41,000,000
Under/Over Recovered Transmission Costs [Member] \| PECO Energy Co [Member]
Regulatory Matters Additional Narrative Information [Line Items]
Regulatory Liabilities						28,000,000												28,000,000
Regulatory Assets						0				0								0	0
Under/Over Recovered Transmission Costs [Member] \| Commonwealth Edison Co [Member]
Regulatory Matters Additional Narrative Information [Line Items]
Regulatory Assets						0				6,000,000								0	6,000,000
Under/Over Recovered Transmission Costs [Member] \| Baltimore Gas and Electric Company [Member]
Regulatory Matters Additional Narrative Information [Line Items]
Regulatory Assets						1,000,000				4,000,000								1,000,000	4,000,000
Under/Over Recovered Transmission Costs [Member] \| Pepco Holdings LLC [Member]
Regulatory Matters Additional Narrative Information [Line Items]
Regulatory Assets						10,000,000				31,000,000								10,000,000	31,000,000
Under/Over Recovered Transmission Costs [Member] \| Potomac Electric Power Company [Member]
Regulatory Matters Additional Narrative Information [Line Items]
Regulatory Assets						1,000,000				10,000,000								1,000,000	10,000,000
Under/Over Recovered Transmission Costs [Member] \| Delmarva Power & Light Company [Member]
Regulatory Matters Additional Narrative Information [Line Items]
Regulatory Assets						2,000,000				14,000,000								2,000,000	14,000,000
Under/Over Recovered Transmission Costs [Member] \| Atlantic City Electric Company [Member]
Regulatory Matters Additional Narrative Information [Line Items]
Regulatory Assets						7,000,000				7,000,000								7,000,000	7,000,000
MergerIntegrationCostsToBeRecoveredInMarylandServiceTerritory [Member] \| Potomac Electric Power Company [Member]
Regulatory Matters Additional Narrative Information [Line Items]
Regulatory Assets						6,000,000				9,000,000								6,000,000	9,000,000
MergerIntegrationCostsToBeRecoveredInDCServiceTerritory [Member] \| Potomac Electric Power Company [Member]
Regulatory Matters Additional Narrative Information [Line Items]
Regulatory Assets						9,000,000				9,000,000								9,000,000	9,000,000
Difference between Carrying Value and Fair Value [Member] \| Baltimore Gas and Electric Company [Member]
Regulatory Matters Additional Narrative Information [Line Items]
Regulatory Assets						127,000,000				133,000,000								127,000,000	133,000,000
Difference between Carrying Value and Fair Value [Member] \| Pepco Holdings LLC [Member]
Regulatory Matters Additional Narrative Information [Line Items]
Regulatory Assets						523,000,000				569,000,000								523,000,000	569,000,000
DC PLUG Charge [Member]
Regulatory Matters Additional Narrative Information [Line Items]
Regulatory Assets						126,000,000				159,000,000								126,000,000	159,000,000
DC PLUG Charge [Member] \| PECO Energy Co [Member]
Regulatory Matters Additional Narrative Information [Line Items]
Regulatory Assets						0				0								0	0
DC PLUG Charge [Member] \| Commonwealth Edison Co [Member]
Regulatory Matters Additional Narrative Information [Line Items]
Regulatory Assets						0				0								0	0
DC PLUG Charge [Member] \| Baltimore Gas and Electric Company [Member]
Regulatory Matters Additional Narrative Information [Line Items]
Regulatory Assets						0				0								0	0
DC PLUG Charge [Member] \| Pepco Holdings LLC [Member]
Regulatory Matters Additional Narrative Information [Line Items]
Regulatory Assets						126,000,000				159,000,000								126,000,000	159,000,000
DC PLUG Charge [Member] \| Potomac Electric Power Company [Member]
Regulatory Matters Additional Narrative Information [Line Items]
Regulatory Assets						126,000,000				159,000,000								126,000,000	159,000,000
DC PLUG Charge [Member] \| Delmarva Power & Light Company [Member]
Regulatory Matters Additional Narrative Information [Line Items]
Regulatory Assets						0				0								0	0
DC PLUG Charge [Member] \| Atlantic City Electric Company [Member]
Regulatory Matters Additional Narrative Information [Line Items]
Regulatory Assets						0				0								0	0
AMI Expenses [Member] \| Baltimore Gas and Electric Company [Member]
Regulatory Matters Additional Narrative Information [Line Items]
Regulatory Assets						32,000,000				10,000,000								32,000,000	10,000,000
Advanced Metering Infrastructure Legacy Meter Costs [Member]
Regulatory Matters Additional Narrative Information [Line Items]
Regulatory Assets						276,000,000				328,000,000								276,000,000	328,000,000
Advanced Metering Infrastructure Legacy Meter Costs [Member] \| PECO Energy Co [Member]
Regulatory Matters Additional Narrative Information [Line Items]
Regulatory Assets						12,000,000				24,000,000								12,000,000	24,000,000
Advanced Metering Infrastructure Legacy Meter Costs [Member] \| Commonwealth Edison Co [Member]
Regulatory Matters Additional Narrative Information [Line Items]
Regulatory Assets						113,000,000				136,000,000								113,000,000	136,000,000
Advanced Metering Infrastructure Legacy Meter Costs [Member] \| Baltimore Gas and Electric Company [Member]
Regulatory Matters Additional Narrative Information [Line Items]
Regulatory Assets						45,000,000				48,000,000								45,000,000	48,000,000
Advanced Metering Infrastructure Legacy Meter Costs [Member] \| Pepco Holdings LLC [Member]
Regulatory Matters Additional Narrative Information [Line Items]
Regulatory Assets						106,000,000				120,000,000								106,000,000	120,000,000
Advanced Metering Infrastructure Legacy Meter Costs [Member] \| Potomac Electric Power Company [Member]
Regulatory Matters Additional Narrative Information [Line Items]
Regulatory Assets						79,000,000				90,000,000								79,000,000	90,000,000
Advanced Metering Infrastructure Legacy Meter Costs [Member] \| Delmarva Power & Light Company [Member]
Regulatory Matters Additional Narrative Information [Line Items]
Regulatory Assets						27,000,000				30,000,000								27,000,000	30,000,000
Advanced Metering Infrastructure Legacy Meter Costs [Member] \| Atlantic City Electric Company [Member]
Regulatory Matters Additional Narrative Information [Line Items]
Regulatory Assets						0				0								0	0
Maximum [Member] \| Exelon Generation Co L L C [Member]
Regulatory Matters Additional Narrative Information [Line Items]
Purchase Obligation						14,000,000												14,000,000
Minimum [Member] \| Exelon Generation Co L L C [Member]
Regulatory Matters Additional Narrative Information [Line Items]
Purchase Obligation						11,000,000												11,000,000
One-Time Revenue Adjustment [Member] \| Maximum [Member]
Regulatory Matters Additional Narrative Information [Line Items]
Amount of Impairment to Carrying Amount of Regulatory Assets						79,000,000												79,000,000
One-Time Revenue Adjustment [Member] \| Maximum [Member] \| Commonwealth Edison Co [Member]
Regulatory Matters Additional Narrative Information [Line Items]
Amount of Impairment to Carrying Amount of Regulatory Assets						51,000,000												51,000,000
One-Time Revenue Adjustment [Member] \| Maximum [Member] \| Baltimore Gas and Electric Company [Member]
Regulatory Matters Additional Narrative Information [Line Items]
Amount of Impairment to Carrying Amount of Regulatory Assets						17,000,000												17,000,000
One-Time Revenue Adjustment [Member] \| Maximum [Member] \| Pepco Holdings LLC [Member]
Regulatory Matters Additional Narrative Information [Line Items]
Amount of Impairment to Carrying Amount of Regulatory Assets						11,000,000												11,000,000
One-Time Revenue Adjustment [Member] \| Maximum [Member] \| Potomac Electric Power Company [Member]
Regulatory Matters Additional Narrative Information [Line Items]
Amount of Impairment to Carrying Amount of Regulatory Assets						4,000,000												4,000,000
One-Time Revenue Adjustment [Member] \| Maximum [Member] \| Delmarva Power & Light Company [Member]
Regulatory Matters Additional Narrative Information [Line Items]
Amount of Impairment to Carrying Amount of Regulatory Assets						5,000,000												5,000,000
One-Time Revenue Adjustment [Member] \| Maximum [Member] \| Atlantic City Electric Company [Member]
Regulatory Matters Additional Narrative Information [Line Items]
Amount of Impairment to Carrying Amount of Regulatory Assets						2,000,000												2,000,000
PJM Transmission Rate Design Settlement [Member]
Regulatory Matters Additional Narrative Information [Line Items]
Accounts Payable, Current										176,000,000									176,000,000
PJM Transmission Rate Design Settlement [Member] \| PECO Energy Co [Member]
Regulatory Matters Additional Narrative Information [Line Items]
Accounts Payable, Current										0									0
PJM Transmission Rate Design Settlement [Member] \| Commonwealth Edison Co [Member]
Regulatory Matters Additional Narrative Information [Line Items]
Accounts Payable, Current										0									0
PJM Transmission Rate Design Settlement [Member] \| Baltimore Gas and Electric Company [Member]
Regulatory Matters Additional Narrative Information [Line Items]
Accounts Payable, Current										51,000,000									51,000,000
PJM Transmission Rate Design Settlement [Member] \| Pepco Holdings LLC [Member]
Regulatory Matters Additional Narrative Information [Line Items]
Accounts Payable, Current										84,000,000									84,000,000
PJM Transmission Rate Design Settlement [Member] \| Potomac Electric Power Company [Member]
Regulatory Matters Additional Narrative Information [Line Items]
Accounts Payable, Current										84,000,000									84,000,000
PJM Transmission Rate Design Settlement [Member] \| Delmarva Power & Light Company [Member]
Regulatory Matters Additional Narrative Information [Line Items]
Accounts Payable, Current										0									0
PJM Transmission Rate Design Settlement [Member] \| Atlantic City Electric Company [Member]
Regulatory Matters Additional Narrative Information [Line Items]
Accounts Payable, Current										0									0
PJM Transmission Rate Design Settlement [Member] \| Exelon Generation Co L L C [Member]
Regulatory Matters Additional Narrative Information [Line Items]
Accounts Payable, Current										$ 41,000,000									41,000,000
Illinois Utilities [Member]
Regulatory Matters Additional Narrative Information [Line Items]
Purchase Obligation																										$ 235,000,000
Energy Commodities and Service [Member]
Regulatory Matters Additional Narrative Information [Line Items]
Revenue from Contract with Customer, Including Assessed Tax																		17,754,000,000	19,168,000,000	17,394,000,000
Energy Commodities and Service [Member] \| Exelon Generation Co L L C [Member]
Regulatory Matters Additional Narrative Information [Line Items]
Revenue from Contract with Customer, Including Assessed Tax																		17,752,000,000	19,169,000,000	$ 17,385,000,000
Zero Emission Standard [Member] \| Energy Commodities and Service [Member] \| Exelon Generation Co L L C [Member]
Regulatory Matters Additional Narrative Information [Line Items]
Revenue from Contract with Customer, Including Assessed Tax																$ 150,000,000
Clean Energy Legislation [Member] \| Exelon Generation Co L L C [Member]
Regulatory Matters Additional Narrative Information [Line Items]
Competitive businesses other revenues																		53,000,000
One-Time Revenue Adjustment [Member] \| Exelon Generation Co L L C [Member]
Regulatory Matters Additional Narrative Information [Line Items]
Revenues					$ 101,000,000
Conowingo [Member] \| Exelon Generation Co L L C [Member]
Regulatory Matters Additional Narrative Information [Line Items]
Environmental Costs Recognized, Capitalized						$ 42,000,000												$ 42,000,000
Nuclear Plant [Member] \| Salem [Member] \| Exelon Generation Co L L C [Member]
Regulatory Matters Additional Narrative Information [Line Items]
Ownership interest						42.59%												42.59%
Forecast [Member] \| Baltimore Gas and Electric Company [Member]
Regulatory Matters Additional Narrative Information [Line Items]
Proposed Capital Expenditure																								$ 732,000,000
Payments to Acquire Property, Plant, and Equipment																								$ 200,000,000
Forecast [Member] \| Potomac Electric Power Company [Member]
Regulatory Matters Additional Narrative Information [Line Items]
Proposed Capital Expenditure																	$ 30,000,000				$ 67,000,000				$ 500,000,000
Forecast [Member] \| Atlantic City Electric Company [Member]
Regulatory Matters Additional Narrative Information [Line Items]
Proposed Capital Expenditure																							$ 338,000,000
Payments to Acquire Property, Plant, and Equipment																						$ 96,000,000
Forecast [Member] \| DC PLUG Charge [Member] \| Potomac Electric Power Company [Member]
Regulatory Matters Additional Narrative Information [Line Items]
Proposed Capital Expenditure																									250,000,000
DISTRICT OF COLUMBIA \| Forecast [Member] \| DC PLUG Charge [Member]
Regulatory Matters Additional Narrative Information [Line Items]
Proposed Capital Expenditure																									$ 250,000,000
ILLINOIS \| Exelon Generation Co L L C [Member]
Regulatory Matters Additional Narrative Information [Line Items]
exc_ZECChargeperMWh																			$ 16.50
NEW JERSEY \| Exelon Generation Co L L C [Member]
Regulatory Matters Additional Narrative Information [Line Items]
exc_ZECChargeperMWh																		$ 10
NEW YORK \| Exelon Generation Co L L C [Member]
Regulatory Matters Additional Narrative Information [Line Items]
exc_ZECChargeperMWh																		$ 17.48
CENG [Member]
Regulatory Matters Additional Narrative Information [Line Items]
Noncontrolling Interest, Ownership Percentage by Noncontrolling Owners						49.99%												49.99%
CENG [Member] \| Exelon Generation Co L L C [Member]
Regulatory Matters Additional Narrative Information [Line Items]
Noncontrolling Interest, Ownership Percentage by Noncontrolling Owners						49.99%												49.99%