Income Taxes - Tax Effects of Temporary Differences and Carryforwards (Details) - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022
Operating Loss Carryforwards [Line Items]
Plant basis differences	$ (12,631)	$ (12,130)
Accrual based contracts	8	10
Derivatives and other financial instruments	46	26
Deferred pension and postretirement obligation	524	551
Deferred debt refinancing costs	115	132
Regulatory assets and liabilities	(1,429)	(1,107)
Tax loss carryforward, net of valuation allowances	295	250
Tax credit carryforward	281	468
Corporate Alternative Minimum Tax	264
Investment in partnerships	(28)	(21)
Deferred Tax Assets, Other	619	591
Deferred income tax liabilities (net)	(11,936)	(11,230)
Unamortized investment tax credits	(13)	(14)
Total deferred income tax liabilities (net) and unamortized investment tax credits	(11,949)	(11,244)
Domestic Tax Authority
Operating Loss Carryforwards [Line Items]
Corporate Alternative Minimum Tax	264
Commonwealth Edison Co
Operating Loss Carryforwards [Line Items]
Plant basis differences	(4,993)	(4,823)
Accrual based contracts	0	0
Derivatives and other financial instruments	37	23
Deferred pension and postretirement obligation	(299)	(300)
Deferred debt refinancing costs	(5)	(5)
Regulatory assets and liabilities	(405)	(131)
Tax loss carryforward, net of valuation allowances	0	0
Tax credit carryforward	0	0
Corporate Alternative Minimum Tax	118
Investment in partnerships	0	0
Deferred Tax Assets, Other	227	223
Deferred income tax liabilities (net)	(5,320)	(5,013)
Unamortized investment tax credits	(7)	(8)
Total deferred income tax liabilities (net) and unamortized investment tax credits	(5,327)	(5,021)
Commonwealth Edison Co | Domestic Tax Authority
Operating Loss Carryforwards [Line Items]
Corporate Alternative Minimum Tax	118
PECO Energy Co
Operating Loss Carryforwards [Line Items]
Plant basis differences	(2,264)	(2,119)
Accrual based contracts	0	0
Derivatives and other financial instruments	0	0
Deferred pension and postretirement obligation	(36)	(31)
Deferred debt refinancing costs	0	0
Regulatory assets and liabilities	(208)	(169)
Tax loss carryforward, net of valuation allowances	47	33
Tax credit carryforward	0	0
Corporate Alternative Minimum Tax	82
Investment in partnerships	0	0
Deferred Tax Assets, Other	58	73
Deferred income tax liabilities (net)	(2,321)	(2,213)
Unamortized investment tax credits	0	0
Total deferred income tax liabilities (net) and unamortized investment tax credits	(2,321)	(2,213)
PECO Energy Co | Domestic Tax Authority
Operating Loss Carryforwards [Line Items]
Corporate Alternative Minimum Tax	82
Baltimore Gas and Electric Company
Operating Loss Carryforwards [Line Items]
Plant basis differences	(2,064)	(1,949)
Accrual based contracts	0	0
Derivatives and other financial instruments	0	0
Deferred pension and postretirement obligation	(26)	(31)
Deferred debt refinancing costs	(2)	(2)
Regulatory assets and liabilities	(4)	57
Tax loss carryforward, net of valuation allowances	77	72
Tax credit carryforward	0	0
Corporate Alternative Minimum Tax	55
Investment in partnerships	0	0
Deferred Tax Assets, Other	21	23
Deferred income tax liabilities (net)	(1,943)	(1,830)
Unamortized investment tax credits	(2)	(2)
Total deferred income tax liabilities (net) and unamortized investment tax credits	(1,945)	(1,832)
Baltimore Gas and Electric Company | Domestic Tax Authority
Operating Loss Carryforwards [Line Items]
Corporate Alternative Minimum Tax	55
Pepco Holdings LLC
Operating Loss Carryforwards [Line Items]
Plant basis differences	(3,262)	(3,131)
Accrual based contracts	8	10
Derivatives and other financial instruments	2	2
Deferred pension and postretirement obligation	(78)	(80)
Deferred debt refinancing costs	104	111
Regulatory assets and liabilities	(52)	(50)
Tax loss carryforward, net of valuation allowances	72	71
Tax credit carryforward	0	0
Corporate Alternative Minimum Tax	0
Investment in partnerships	0	0
Deferred Tax Assets, Other	186	182
Deferred income tax liabilities (net)	(3,020)	(2,885)
Unamortized investment tax credits	(4)	(4)
Total deferred income tax liabilities (net) and unamortized investment tax credits	(3,024)	(2,889)
Pepco Holdings LLC | Domestic Tax Authority
Operating Loss Carryforwards [Line Items]
Corporate Alternative Minimum Tax	0
Potomac Electric Power Company
Operating Loss Carryforwards [Line Items]
Plant basis differences	(1,454)	(1,394)
Accrual based contracts	0	0
Derivatives and other financial instruments	0	0
Deferred pension and postretirement obligation	(70)	(76)
Deferred debt refinancing costs	(3)	(4)
Regulatory assets and liabilities	9	7
Tax loss carryforward, net of valuation allowances	0	3
Tax credit carryforward	0	0
Corporate Alternative Minimum Tax	0
Investment in partnerships	0	0
Deferred Tax Assets, Other	88	83
Deferred income tax liabilities (net)	(1,430)	(1,381)
Unamortized investment tax credits	(1)	(1)
Total deferred income tax liabilities (net) and unamortized investment tax credits	(1,431)	(1,382)
Potomac Electric Power Company | Domestic Tax Authority
Operating Loss Carryforwards [Line Items]
Corporate Alternative Minimum Tax	0
Delmarva Power & Light Company
Operating Loss Carryforwards [Line Items]
Plant basis differences	(947)	(906)
Accrual based contracts	0	0
Derivatives and other financial instruments	0	0
Deferred pension and postretirement obligation	(35)	(39)
Deferred debt refinancing costs	(2)	(2)
Regulatory assets and liabilities	45	43
Tax loss carryforward, net of valuation allowances	18	20
Tax credit carryforward	0	0
Corporate Alternative Minimum Tax	2
Investment in partnerships	0	0
Deferred Tax Assets, Other	16	16
Deferred income tax liabilities (net)	(903)	(868)
Unamortized investment tax credits	(1)	(1)
Total deferred income tax liabilities (net) and unamortized investment tax credits	(904)	(869)
Delmarva Power & Light Company | Domestic Tax Authority
Operating Loss Carryforwards [Line Items]
Corporate Alternative Minimum Tax	2
Atlantic City Electric Company
Operating Loss Carryforwards [Line Items]
Plant basis differences	(850)	(813)
Accrual based contracts	0	0
Derivatives and other financial instruments	0	0
Deferred pension and postretirement obligation	(2)	(3)
Deferred debt refinancing costs	(1)	(1)
Regulatory assets and liabilities	(4)	11
Tax loss carryforward, net of valuation allowances	52	46
Tax credit carryforward	0	0
Corporate Alternative Minimum Tax	11
Investment in partnerships	0	0
Deferred Tax Assets, Other	25	28
Deferred income tax liabilities (net)	(769)	(732)
Unamortized investment tax credits	(2)	(2)
Total deferred income tax liabilities (net) and unamortized investment tax credits	(771)	$ (734)
Atlantic City Electric Company | Domestic Tax Authority
Operating Loss Carryforwards [Line Items]
Corporate Alternative Minimum Tax	$ 11