Supplemental Financial Information - Cash Flow (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Depreciation, Amortization and Accretion [Abstract]
Property, plant and equipment			$ 2,073	$ 2,024
Amortization of regulatory assets			537	532
Amortization of intangible assets, net			6	10
Amortization of energy contract assets and liabilities				3
Nuclear fuel				66
ARO accretion				44
Depreciation and amortization			2,616	2,679
Other Non-Cash Operating Activities [Abstract]
Pension and non-pension postretirement benefit costs			152	124
Allowance for credit losses			86	130
Other decommissioning-related activity				36
Energy-related options				60
True-up adjustments to decoupling mechanisms and formula rates	$ 108	$ 64	513	92
Long-term incentive plan				35
Amortization of operating ROU asset			29	47
Change in environmental liabilities			37
AFUDC - Equity	(40)	(38)	(113)	(112)
Other Non-Cash Activity
Other Non-Cash Operating Activities [Abstract]
True-up adjustments to decoupling mechanisms and formula rates			(522)	(92)
Return on borrowed funds
Other Non-Cash Operating Activities [Abstract]
AFUDC - Equity			(113)	(112)
Commonwealth Edison Co
Depreciation, Amortization and Accretion [Abstract]
Property, plant and equipment			815	770
Amortization of regulatory assets			230	212
Amortization of intangible assets, net			0	0
Amortization of energy contract assets and liabilities				0
Nuclear fuel				0
ARO accretion				0
Depreciation and amortization			1,045	982
Other Non-Cash Operating Activities [Abstract]
Pension and non-pension postretirement benefit costs			19	45
Allowance for credit losses			4	40
Other decommissioning-related activity				0
Energy-related options				0
True-up adjustments to decoupling mechanisms and formula rates	135	88	405	163
Long-term incentive plan				0
Amortization of operating ROU asset			2	1
Change in environmental liabilities			0
AFUDC - Equity	(7)	(10)	(25)	(28)
Commonwealth Edison Co | Other Non-Cash Activity
Other Non-Cash Operating Activities [Abstract]
True-up adjustments to decoupling mechanisms and formula rates			(405)	(163)
Commonwealth Edison Co | Return on borrowed funds
Other Non-Cash Operating Activities [Abstract]
AFUDC - Equity			(25)	(28)
PECO Energy Co
Depreciation, Amortization and Accretion [Abstract]
Property, plant and equipment			287	267
Amortization of regulatory assets			10	10
Amortization of intangible assets, net			0	0
Amortization of energy contract assets and liabilities				0
Nuclear fuel				0
ARO accretion				0
Depreciation and amortization			297	277
Other Non-Cash Operating Activities [Abstract]
Pension and non-pension postretirement benefit costs			(10)	(6)
Allowance for credit losses			31	32
Other decommissioning-related activity				0
Energy-related options				0
True-up adjustments to decoupling mechanisms and formula rates	11	(5)	1	1
Long-term incentive plan				0
Amortization of operating ROU asset			0	0
Change in environmental liabilities			0
AFUDC - Equity	(10)	(7)	(22)	(22)
PECO Energy Co | Other Non-Cash Activity
Other Non-Cash Operating Activities [Abstract]
True-up adjustments to decoupling mechanisms and formula rates			(1)	(1)
PECO Energy Co | Return on borrowed funds
Other Non-Cash Operating Activities [Abstract]
AFUDC - Equity			(22)	(22)
Baltimore Gas and Electric Company
Depreciation, Amortization and Accretion [Abstract]
Property, plant and equipment			381	355
Amortization of regulatory assets			106	115
Amortization of intangible assets, net			0	0
Amortization of energy contract assets and liabilities				0
Nuclear fuel				0
ARO accretion				0
Depreciation and amortization			487	470
Other Non-Cash Operating Activities [Abstract]
Pension and non-pension postretirement benefit costs			41	34
Allowance for credit losses			4	18
Other decommissioning-related activity				0
Energy-related options				0
True-up adjustments to decoupling mechanisms and formula rates	(22)	(8)	47	(40)
Long-term incentive plan				0
Amortization of operating ROU asset			4	14
Change in environmental liabilities			0
AFUDC - Equity	(4)	(5)	(11)	(17)
Baltimore Gas and Electric Company | Other Non-Cash Activity
Other Non-Cash Operating Activities [Abstract]
True-up adjustments to decoupling mechanisms and formula rates			(47)	40
Baltimore Gas and Electric Company | Return on borrowed funds
Other Non-Cash Operating Activities [Abstract]
AFUDC - Equity			(11)	(17)
Pepco Holdings LLC
Depreciation, Amortization and Accretion [Abstract]
Property, plant and equipment			550	502
Amortization of regulatory assets			191	195
Amortization of intangible assets, net			0	0
Amortization of energy contract assets and liabilities				0
Nuclear fuel				0
ARO accretion				0
Depreciation and amortization			741	697
Other Non-Cash Operating Activities [Abstract]
Pension and non-pension postretirement benefit costs			74	39
Allowance for credit losses			47	42
Other decommissioning-related activity				0
Energy-related options				0
True-up adjustments to decoupling mechanisms and formula rates	(15)	(11)	59	(33)
Long-term incentive plan				0
Amortization of operating ROU asset			21	21
Change in environmental liabilities			37
AFUDC - Equity	(19)	(16)	(55)	(45)
Pepco Holdings LLC | Other Non-Cash Activity
Other Non-Cash Operating Activities [Abstract]
True-up adjustments to decoupling mechanisms and formula rates			(69)	33
Pepco Holdings LLC | Return on borrowed funds
Other Non-Cash Operating Activities [Abstract]
AFUDC - Equity			(55)	(45)
Potomac Electric Power Company
Depreciation, Amortization and Accretion [Abstract]
Property, plant and equipment			232	214
Amortization of regulatory assets			97	98
Amortization of intangible assets, net			0	0
Amortization of energy contract assets and liabilities				0
Nuclear fuel				0
ARO accretion				0
Depreciation and amortization			329	312
Other Non-Cash Operating Activities [Abstract]
Pension and non-pension postretirement benefit costs			26	6
Allowance for credit losses			27	21
Other decommissioning-related activity				0
Energy-related options				0
True-up adjustments to decoupling mechanisms and formula rates	(18)	(8)	28	(15)
Long-term incentive plan				0
Amortization of operating ROU asset			5	5
Change in environmental liabilities			37
AFUDC - Equity	(15)	(12)	(42)	(35)
Potomac Electric Power Company | Other Non-Cash Activity
Other Non-Cash Operating Activities [Abstract]
True-up adjustments to decoupling mechanisms and formula rates			(28)	15
Potomac Electric Power Company | Return on borrowed funds
Other Non-Cash Operating Activities [Abstract]
AFUDC - Equity			(42)	(35)
Delmarva Power and Light Company
Depreciation, Amortization and Accretion [Abstract]
Property, plant and equipment			155	141
Amortization of regulatory assets			27	31
Amortization of intangible assets, net			0	0
Amortization of energy contract assets and liabilities				0
Nuclear fuel				0
ARO accretion				0
Depreciation and amortization			182	172
Other Non-Cash Operating Activities [Abstract]
Pension and non-pension postretirement benefit costs			13	3
Allowance for credit losses			9	9
Other decommissioning-related activity				0
Energy-related options				0
True-up adjustments to decoupling mechanisms and formula rates	(2)	0	10	(3)
Long-term incentive plan				0
Amortization of operating ROU asset			6	6
Change in environmental liabilities			0
AFUDC - Equity	(3)	(2)	(7)	(5)
Delmarva Power and Light Company | Other Non-Cash Activity
Other Non-Cash Operating Activities [Abstract]
True-up adjustments to decoupling mechanisms and formula rates			(15)	3
Delmarva Power and Light Company | Return on borrowed funds
Other Non-Cash Operating Activities [Abstract]
AFUDC - Equity			(7)	(5)
Atlantic City Electric Company
Depreciation, Amortization and Accretion [Abstract]
Property, plant and equipment			145	126
Amortization of regulatory assets			67	66
Amortization of intangible assets, net			0	0
Amortization of energy contract assets and liabilities				0
Nuclear fuel				0
ARO accretion				0
Depreciation and amortization			212	192
Other Non-Cash Operating Activities [Abstract]
Pension and non-pension postretirement benefit costs			10	9
Allowance for credit losses			11	12
Other decommissioning-related activity				0
Energy-related options				0
True-up adjustments to decoupling mechanisms and formula rates	5	(3)	21	(14)
Long-term incentive plan				0
Amortization of operating ROU asset			2	3
Change in environmental liabilities			0
AFUDC - Equity	$ (1)	$ (2)	(6)	(5)
Atlantic City Electric Company | Other Non-Cash Activity
Other Non-Cash Operating Activities [Abstract]
True-up adjustments to decoupling mechanisms and formula rates			(26)	14
Atlantic City Electric Company | Return on borrowed funds
Other Non-Cash Operating Activities [Abstract]
AFUDC - Equity			$ (6)	$ (5)