Supplemental Financial Information - Cash Flow (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Depreciation, Amortization and Accretion [Abstract]
Property, plant and equipment	$ 711	$ 680
Amortization of regulatory assets	166	178
Amortization of intangible assets, net	2	2
Accretion expense	1
Depreciation and amortization	880	860
Other Non-Cash Operating Activities [Abstract]
Pension and non-pension postretirement benefit costs	61	45
Allowance for credit losses	63	70
True-up adjustments to decoupling mechanisms and formula rates	106	279
Long-term incentive plan		2
Amortization of operating ROU asset	9	10
Change in environmental liabilities		25
AFUDC - Equity	(40)	(38)
Other Non-Cash Activity
Other Non-Cash Operating Activities [Abstract]
True-up adjustments to decoupling mechanisms and formula rates	(91)	(282)
Return on borrowed funds
Other Non-Cash Operating Activities [Abstract]
AFUDC - Equity	(40)	(38)
Commonwealth Edison Co
Depreciation, Amortization and Accretion [Abstract]
Property, plant and equipment	284	267
Amortization of regulatory assets	78	71
Amortization of intangible assets, net	0	0
Accretion expense	0
Depreciation and amortization	362	338
Other Non-Cash Operating Activities [Abstract]
Pension and non-pension postretirement benefit costs	17	6
Allowance for credit losses	2	0
True-up adjustments to decoupling mechanisms and formula rates	19	153
Long-term incentive plan		0
Amortization of operating ROU asset	0	1
Change in environmental liabilities		0
AFUDC - Equity	(10)	(10)
Commonwealth Edison Co | Other Non-Cash Activity
Other Non-Cash Operating Activities [Abstract]
True-up adjustments to decoupling mechanisms and formula rates	(19)	(153)
Commonwealth Edison Co | Return on borrowed funds
Other Non-Cash Operating Activities [Abstract]
AFUDC - Equity	(10)	(10)
PECO Energy Co
Depreciation, Amortization and Accretion [Abstract]
Property, plant and equipment	101	95
Amortization of regulatory assets	3	3
Amortization of intangible assets, net	0	0
Accretion expense	0
Depreciation and amortization	104	98
Other Non-Cash Operating Activities [Abstract]
Pension and non-pension postretirement benefit costs	0	(3)
Allowance for credit losses	27	37
True-up adjustments to decoupling mechanisms and formula rates	(2)	(4)
Long-term incentive plan		0
Amortization of operating ROU asset	0	0
Change in environmental liabilities		0
AFUDC - Equity	(8)	(6)
PECO Energy Co | Other Non-Cash Activity
Other Non-Cash Operating Activities [Abstract]
True-up adjustments to decoupling mechanisms and formula rates	2	4
PECO Energy Co | Return on borrowed funds
Other Non-Cash Operating Activities [Abstract]
AFUDC - Equity	(8)	(6)
Baltimore Gas and Electric Company
Depreciation, Amortization and Accretion [Abstract]
Property, plant and equipment	122	124
Amortization of regulatory assets	28	43
Amortization of intangible assets, net	0	0
Accretion expense	0
Depreciation and amortization	150	167
Other Non-Cash Operating Activities [Abstract]
Pension and non-pension postretirement benefit costs	15	14
Allowance for credit losses	12	18
True-up adjustments to decoupling mechanisms and formula rates	43	65
Long-term incentive plan		0
Amortization of operating ROU asset	2	1
Change in environmental liabilities		0
AFUDC - Equity	(7)	(3)
Baltimore Gas and Electric Company | Other Non-Cash Activity
Other Non-Cash Operating Activities [Abstract]
True-up adjustments to decoupling mechanisms and formula rates	(43)	(65)
Baltimore Gas and Electric Company | Return on borrowed funds
Other Non-Cash Operating Activities [Abstract]
AFUDC - Equity	(7)	(3)
Pepco Holdings LLC
Depreciation, Amortization and Accretion [Abstract]
Property, plant and equipment	190	180
Amortization of regulatory assets	56	61
Amortization of intangible assets, net	0	0
Accretion expense	0
Depreciation and amortization	246	241
Other Non-Cash Operating Activities [Abstract]
Pension and non-pension postretirement benefit costs	23	24
Allowance for credit losses	22	15
True-up adjustments to decoupling mechanisms and formula rates	46	65
Long-term incentive plan		0
Amortization of operating ROU asset	6	7
Change in environmental liabilities		25
AFUDC - Equity	(15)	(19)
Pepco Holdings LLC | Other Non-Cash Activity
Other Non-Cash Operating Activities [Abstract]
True-up adjustments to decoupling mechanisms and formula rates	(31)	(68)
Pepco Holdings LLC | Return on borrowed funds
Other Non-Cash Operating Activities [Abstract]
AFUDC - Equity	(15)	(19)
Potomac Electric Power Company
Depreciation, Amortization and Accretion [Abstract]
Property, plant and equipment	81	76
Amortization of regulatory assets	26	32
Amortization of intangible assets, net	0	0
Accretion expense	0
Depreciation and amortization	107	108
Other Non-Cash Operating Activities [Abstract]
Pension and non-pension postretirement benefit costs	9	8
Allowance for credit losses	16	7
True-up adjustments to decoupling mechanisms and formula rates	29	39
Long-term incentive plan		0
Amortization of operating ROU asset	1	1
Change in environmental liabilities		25
AFUDC - Equity	(12)	(14)
Potomac Electric Power Company | Other Non-Cash Activity
Other Non-Cash Operating Activities [Abstract]
True-up adjustments to decoupling mechanisms and formula rates	(29)	(39)
Potomac Electric Power Company | Return on borrowed funds
Other Non-Cash Operating Activities [Abstract]
AFUDC - Equity	(12)	(14)
Delmarva Power and Light Company
Depreciation, Amortization and Accretion [Abstract]
Property, plant and equipment	52	51
Amortization of regulatory assets	9	9
Amortization of intangible assets, net	0	0
Accretion expense	0
Depreciation and amortization	61	60
Other Non-Cash Operating Activities [Abstract]
Pension and non-pension postretirement benefit costs	4	4
Allowance for credit losses	3	5
True-up adjustments to decoupling mechanisms and formula rates	4	9
Long-term incentive plan		0
Amortization of operating ROU asset	2	2
Change in environmental liabilities		0
AFUDC - Equity	(3)	(2)
Delmarva Power and Light Company | Other Non-Cash Activity
Other Non-Cash Operating Activities [Abstract]
True-up adjustments to decoupling mechanisms and formula rates	4	(11)
Delmarva Power and Light Company | Return on borrowed funds
Other Non-Cash Operating Activities [Abstract]
AFUDC - Equity	(3)	(2)
Atlantic City Electric Company
Depreciation, Amortization and Accretion [Abstract]
Property, plant and equipment	53	47
Amortization of regulatory assets	21	20
Amortization of intangible assets, net	0	0
Accretion expense	0
Depreciation and amortization	74	67
Other Non-Cash Operating Activities [Abstract]
Pension and non-pension postretirement benefit costs	3	4
Allowance for credit losses	3	3
True-up adjustments to decoupling mechanisms and formula rates	13	17
Long-term incentive plan		0
Amortization of operating ROU asset	1	1
Change in environmental liabilities		0
AFUDC - Equity	0	(3)
Atlantic City Electric Company | Other Non-Cash Activity
Other Non-Cash Operating Activities [Abstract]
True-up adjustments to decoupling mechanisms and formula rates	(6)	(18)
Atlantic City Electric Company | Return on borrowed funds
Other Non-Cash Operating Activities [Abstract]
AFUDC - Equity	$ 0	$ (3)