Income Taxes - Tax Effects of Temporary Differences and Carryforwards (Details) - USD ($) $ in Millions	Dec. 31, 2024	Dec. 31, 2023
Operating Loss Carryforwards [Line Items]
Plant basis differences	$ (13,150)	$ (12,631)
Accrual based contracts	19	8
Derivatives and other financial instruments	21	46
Deferred pension and postretirement obligation	512	524
Deferred debt refinancing costs	108	115
Regulatory assets and liabilities	(1,665)	(1,429)
Tax loss carryforward, net of valuation allowances	283	295
Tax credit carryforward	142	281
Corporate Alternative Minimum Tax	369	264
Investment in partnerships	(27)	(28)
Deferred Tax Assets, Other	612	619
Deferred income tax liabilities (net)	(12,776)	(11,936)
Unamortized investment tax credits	(10)	(13)
Total deferred income tax liabilities (net) and unamortized investment tax credits	(12,786)	(11,949)
Domestic Tax Authority
Operating Loss Carryforwards [Line Items]
Corporate Alternative Minimum Tax	369
Commonwealth Edison Co
Operating Loss Carryforwards [Line Items]
Plant basis differences	(5,069)	(4,993)
Accrual based contracts	0	0
Derivatives and other financial instruments	36	37
Deferred pension and postretirement obligation	(339)	(299)
Deferred debt refinancing costs	(4)	(5)
Regulatory assets and liabilities	(515)	(405)
Tax loss carryforward, net of valuation allowances	0	0
Tax credit carryforward	0	0
Corporate Alternative Minimum Tax	47	118
Investment in partnerships	0	0
Deferred Tax Assets, Other	249	227
Deferred income tax liabilities (net)	(5,595)	(5,320)
Unamortized investment tax credits	(6)	(7)
Total deferred income tax liabilities (net) and unamortized investment tax credits	(5,601)	(5,327)
Commonwealth Edison Co | Domestic Tax Authority
Operating Loss Carryforwards [Line Items]
Corporate Alternative Minimum Tax	47
PECO Energy Co
Operating Loss Carryforwards [Line Items]
Plant basis differences	(2,446)	(2,264)
Accrual based contracts	0	0
Derivatives and other financial instruments	0	0
Deferred pension and postretirement obligation	(39)	(36)
Deferred debt refinancing costs	0	0
Regulatory assets and liabilities	(254)	(208)
Tax loss carryforward, net of valuation allowances	63	47
Tax credit carryforward	0	0
Corporate Alternative Minimum Tax	166	82
Investment in partnerships	0	0
Deferred Tax Assets, Other	77	58
Deferred income tax liabilities (net)	(2,433)	(2,321)
Unamortized investment tax credits	0	0
Total deferred income tax liabilities (net) and unamortized investment tax credits	(2,433)	(2,321)
PECO Energy Co | Domestic Tax Authority
Operating Loss Carryforwards [Line Items]
Corporate Alternative Minimum Tax	166
Baltimore Gas and Electric Company
Operating Loss Carryforwards [Line Items]
Plant basis differences	(2,232)	(2,064)
Accrual based contracts	0	0
Derivatives and other financial instruments	0	0
Deferred pension and postretirement obligation	(24)	(26)
Deferred debt refinancing costs	(2)	(2)
Regulatory assets and liabilities	(37)	(4)
Tax loss carryforward, net of valuation allowances	78	77
Tax credit carryforward	0	0
Corporate Alternative Minimum Tax	95	55
Investment in partnerships	0	0
Deferred Tax Assets, Other	24	21
Deferred income tax liabilities (net)	(2,098)	(1,943)
Unamortized investment tax credits	(1)	(2)
Total deferred income tax liabilities (net) and unamortized investment tax credits	(2,099)	(1,945)
Baltimore Gas and Electric Company | Domestic Tax Authority
Operating Loss Carryforwards [Line Items]
Corporate Alternative Minimum Tax	95
Pepco Holdings LLC
Operating Loss Carryforwards [Line Items]
Plant basis differences	(3,371)	(3,262)
Accrual based contracts	6	8
Derivatives and other financial instruments	1	2
Deferred pension and postretirement obligation	(68)	(78)
Deferred debt refinancing costs	98	104
Regulatory assets and liabilities	(96)	(52)
Tax loss carryforward, net of valuation allowances	68	72
Tax credit carryforward	0	0
Corporate Alternative Minimum Tax	2	0
Investment in partnerships	0	0
Deferred Tax Assets, Other	180	186
Deferred income tax liabilities (net)	(3,180)	(3,020)
Unamortized investment tax credits	(3)	(4)
Total deferred income tax liabilities (net) and unamortized investment tax credits	(3,183)	(3,024)
Pepco Holdings LLC | Domestic Tax Authority
Operating Loss Carryforwards [Line Items]
Corporate Alternative Minimum Tax	2
Potomac Electric Power Company
Operating Loss Carryforwards [Line Items]
Plant basis differences	(1,512)	(1,454)
Accrual based contracts	0	0
Derivatives and other financial instruments	0	0
Deferred pension and postretirement obligation	(64)	(70)
Deferred debt refinancing costs	(3)	(3)
Regulatory assets and liabilities	(16)	9
Tax loss carryforward, net of valuation allowances	0	0
Tax credit carryforward	0	0
Corporate Alternative Minimum Tax	2	0
Investment in partnerships	0	0
Deferred Tax Assets, Other	85	88
Deferred income tax liabilities (net)	(1,508)	(1,430)
Unamortized investment tax credits	(1)	(1)
Total deferred income tax liabilities (net) and unamortized investment tax credits	(1,509)	(1,431)
Potomac Electric Power Company | Domestic Tax Authority
Operating Loss Carryforwards [Line Items]
Corporate Alternative Minimum Tax	2
Delmarva Power & Light Company
Operating Loss Carryforwards [Line Items]
Plant basis differences	(975)	(947)
Accrual based contracts	0	0
Derivatives and other financial instruments	0	0
Deferred pension and postretirement obligation	(32)	(35)
Deferred debt refinancing costs	(1)	(2)
Regulatory assets and liabilities	33	45
Tax loss carryforward, net of valuation allowances	16	18
Tax credit carryforward	0	0
Corporate Alternative Minimum Tax	4	2
Investment in partnerships	0	0
Deferred Tax Assets, Other	10	16
Deferred income tax liabilities (net)	(945)	(903)
Unamortized investment tax credits	(1)	(1)
Total deferred income tax liabilities (net) and unamortized investment tax credits	(946)	(904)
Delmarva Power & Light Company | Domestic Tax Authority
Operating Loss Carryforwards [Line Items]
Corporate Alternative Minimum Tax	4
Atlantic City Electric Company
Operating Loss Carryforwards [Line Items]
Plant basis differences	(881)	(850)
Accrual based contracts	0	0
Derivatives and other financial instruments	0	0
Deferred pension and postretirement obligation	0	(2)
Deferred debt refinancing costs	(1)	(1)
Regulatory assets and liabilities	(18)	(4)
Tax loss carryforward, net of valuation allowances	51	52
Tax credit carryforward	0	0
Corporate Alternative Minimum Tax	8	11
Investment in partnerships	0	0
Deferred Tax Assets, Other	27	25
Deferred income tax liabilities (net)	(814)	(769)
Unamortized investment tax credits	(2)	(2)
Total deferred income tax liabilities (net) and unamortized investment tax credits	(816)	$ (771)
Atlantic City Electric Company | Domestic Tax Authority
Operating Loss Carryforwards [Line Items]
Corporate Alternative Minimum Tax	$ 8