Income Taxes - Tax Effects of Temporary Differences and Carryforwards (Details) - USD ($) $ in Millions	Dec. 31, 2022	Dec. 31, 2021
Operating Loss Carryforwards [Line Items]
Plant basis differences	$ (12,130)	$ (11,606)
Deferred Tax Liabilities, Other Finite-Lived Assets	10	56
Derivatives and other financial instruments	26	63
Deferred pension and postretirement obligation	551	641
Deferred debt refinancing costs	132	146
Deferred Tax Liabilities, Regulatory Assets and Liabilities	(1,107)	(1,130)
Tax loss carryforward, net of valuation allowances	250	242
Tax credit carryforward	468	584
Investment in partnerships	(21)	(21)
Other, net	591	449
Deferred income tax liabilities (net)	(11,230)	(10,576)
Unamortized investment tax credits	(14)	(15)
Total deferred income tax liabilities (net) and unamortized investment tax credits	(11,244)	(10,591)
Commonwealth Edison Co [Member]
Operating Loss Carryforwards [Line Items]
Plant basis differences	(4,823)	(4,648)
Deferred Tax Liabilities, Other Finite-Lived Assets	0	0
Derivatives and other financial instruments	23	61
Deferred pension and postretirement obligation	(300)	(308)
Deferred debt refinancing costs	(5)	(6)
Deferred Tax Liabilities, Regulatory Assets and Liabilities	(131)	8
Tax loss carryforward, net of valuation allowances	0	0
Tax credit carryforward	0	0
Investment in partnerships	0	0
Other, net	223	216
Deferred income tax liabilities (net)	(5,013)	(4,677)
Unamortized investment tax credits	(8)	(8)
Total deferred income tax liabilities (net) and unamortized investment tax credits	(5,021)	(4,685)
PECO Energy Co [Member]
Operating Loss Carryforwards [Line Items]
Plant basis differences	(2,119)	(2,271)
Deferred Tax Liabilities, Other Finite-Lived Assets	0	0
Derivatives and other financial instruments	0	0
Deferred pension and postretirement obligation	(31)	(32)
Deferred debt refinancing costs	0	0
Deferred Tax Liabilities, Regulatory Assets and Liabilities	(169)	(280)
Tax loss carryforward, net of valuation allowances	33	65
Tax credit carryforward	0	0
Investment in partnerships	0	0
Other, net	73	97
Deferred income tax liabilities (net)	(2,213)	(2,421)
Unamortized investment tax credits	0	0
Total deferred income tax liabilities (net) and unamortized investment tax credits	(2,213)	(2,421)
Baltimore Gas and Electric Company [Member]
Operating Loss Carryforwards [Line Items]
Plant basis differences	(1,949)	(1,826)
Deferred Tax Liabilities, Other Finite-Lived Assets	0	0
Derivatives and other financial instruments	0	0
Deferred pension and postretirement obligation	(31)	(37)
Deferred debt refinancing costs	(2)	(2)
Deferred Tax Liabilities, Regulatory Assets and Liabilities	57	92
Tax loss carryforward, net of valuation allowances	72	68
Tax credit carryforward	0	0
Investment in partnerships	0	0
Other, net	23	21
Deferred income tax liabilities (net)	(1,830)	(1,684)
Unamortized investment tax credits	(2)	(2)
Total deferred income tax liabilities (net) and unamortized investment tax credits	(1,832)	(1,686)
Pepco Holdings LLC [Member]
Operating Loss Carryforwards [Line Items]
Plant basis differences	(3,131)	(2,976)
Deferred Tax Liabilities, Other Finite-Lived Assets	10	56
Derivatives and other financial instruments	2	2
Deferred pension and postretirement obligation	(80)	(90)
Deferred debt refinancing costs	111	123
Deferred Tax Liabilities, Regulatory Assets and Liabilities	(50)	(53)
Tax loss carryforward, net of valuation allowances	71	64
Tax credit carryforward	0	0
Investment in partnerships	0	0
Other, net	182	212
Deferred income tax liabilities (net)	(2,885)	(2,662)
Unamortized investment tax credits	(4)	(5)
Total deferred income tax liabilities (net) and unamortized investment tax credits	(2,889)	(2,667)
Potomac Electric Power Company [Member]
Operating Loss Carryforwards [Line Items]
Plant basis differences	(1,394)	(1,321)
Deferred Tax Liabilities, Other Finite-Lived Assets	0	0
Derivatives and other financial instruments	0	0
Deferred pension and postretirement obligation	(76)	(76)
Deferred debt refinancing costs	(4)	(2)
Deferred Tax Liabilities, Regulatory Assets and Liabilities	7	24
Tax loss carryforward, net of valuation allowances	3	2
Tax credit carryforward	0	0
Investment in partnerships	0	0
Other, net	83	99
Deferred income tax liabilities (net)	(1,381)	(1,274)
Unamortized investment tax credits	(1)	(1)
Total deferred income tax liabilities (net) and unamortized investment tax credits	(1,382)	(1,275)
Delmarva Power & Light Company [Member]
Operating Loss Carryforwards [Line Items]
Plant basis differences	(906)	(853)
Deferred Tax Liabilities, Other Finite-Lived Assets	0	0
Derivatives and other financial instruments	0	0
Deferred pension and postretirement obligation	(39)	(40)
Deferred debt refinancing costs	(2)	(1)
Deferred Tax Liabilities, Regulatory Assets and Liabilities	43	55
Tax loss carryforward, net of valuation allowances	20	18
Tax credit carryforward	0	0
Investment in partnerships	0	0
Other, net	16	19
Deferred income tax liabilities (net)	(868)	(802)
Unamortized investment tax credits	(1)	(1)
Total deferred income tax liabilities (net) and unamortized investment tax credits	(869)	(803)
Atlantic City Electric Company [Member]
Operating Loss Carryforwards [Line Items]
Plant basis differences	(813)	(777)
Deferred Tax Liabilities, Other Finite-Lived Assets	0	0
Derivatives and other financial instruments	0	0
Deferred pension and postretirement obligation	(3)	(6)
Deferred debt refinancing costs	(1)	(1)
Deferred Tax Liabilities, Regulatory Assets and Liabilities	11	31
Tax loss carryforward, net of valuation allowances	46	42
Tax credit carryforward	0	0
Investment in partnerships	0	0
Other, net	28	34
Deferred income tax liabilities (net)	(732)	(677)
Unamortized investment tax credits	(2)	(2)
Total deferred income tax liabilities (net) and unamortized investment tax credits	$ (734)	$ (679)