Regulatory Matters Regulatory Matters - Schedule of Regulatory Assets (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017	Jun. 30, 2017
Regulatory Assets [Line Items]
Regulatory Assets	$ 9,459	$ 9,288
Current regulatory assets	1,222	1,267
Noncurrent regulatory assets	8,237	8,021
Pension and Other Postretirement Plans Costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets		2,455
Pension and Post Retirement Plan Merger Costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets	1,266	1,393
Deferred income taxes
Regulatory Assets [Line Items]
Regulatory Assets	414	306
Advanced Metering Infrastructure Deployment Costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets	202	385
Advanced Metering Infrastructure Legacy Meter Costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets	328	223
Advanced Metering Infrastructure Incremental Deployment Costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets	32	32
Electric Distribution Formula Rate Annual Reconciliations [Member]
Regulatory Assets [Line Items]
Regulatory Assets	158	186
Electric Distribution Formula Rate One-time Events [Member]
Regulatory Assets [Line Items]
Regulatory Assets	81	58
Energy efficiency costs
Regulatory Assets [Line Items]
Regulatory Assets	472	166
Fair value of long-term debt
Regulatory Assets [Line Items]
Regulatory Assets		758
Fair value of PHI's unamortized energy contracts
Regulatory Assets [Line Items]
Regulatory Assets	561	750
Asset retirement obligations
Regulatory Assets [Line Items]
Regulatory Assets	118	109
MGP remediation costs
Regulatory Assets [Line Items]
Regulatory Assets	326	295
Renewable Energy Program [Member]
Regulatory Assets [Line Items]
Regulatory Assets	249	258
Electric Energy and Natural Gas Costs
Regulatory Assets [Line Items]
Regulatory Assets	193	47
Under Recovered Transmission Costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets	41	35
Energy efficiency and demand response programs
Regulatory Assets [Line Items]
Regulatory Assets	545	596
Merger integration costs
Regulatory Assets [Line Items]
Regulatory Assets	42	45
Under-recovered revenue decoupling
Regulatory Assets [Line Items]
Regulatory Assets	59	55
Securitized stranded costs
Regulatory Assets [Line Items]
Regulatory Assets	50	79
Removal costs
Regulatory Assets [Line Items]
Regulatory Assets	564	529
DC PLUG charge
Regulatory Assets [Line Items]
Regulatory Assets	159	190
Storm Costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets	41	27
Other
Regulatory Assets [Line Items]
Regulatory Assets	303	311
Commonwealth Edison Co [Member]
Regulatory Assets [Line Items]
Regulatory Assets		1,279
Current regulatory assets	293	225
Noncurrent regulatory assets	1,307	1,054
Commonwealth Edison Co [Member] | Pension and Other Postretirement Plans Costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets		0
Commonwealth Edison Co [Member] | Pension and Post Retirement Plan Merger Costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets	0	0
Commonwealth Edison Co [Member] | Deferred income taxes
Regulatory Assets [Line Items]
Regulatory Assets		0
Commonwealth Edison Co [Member] | Advanced Metering Infrastructure Deployment Costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets	0	0
Commonwealth Edison Co [Member] | Advanced Metering Infrastructure Legacy Meter Costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets	136	155
Commonwealth Edison Co [Member] | Advanced Metering Infrastructure Incremental Deployment Costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets	0	0
Commonwealth Edison Co [Member] | Electric Distribution Formula Rate Annual Reconciliations [Member]
Regulatory Assets [Line Items]
Regulatory Assets	158	186
Commonwealth Edison Co [Member] | Electric Distribution Formula Rate One-time Events [Member]
Regulatory Assets [Line Items]
Regulatory Assets	81	58
Commonwealth Edison Co [Member] | Energy efficiency costs
Regulatory Assets [Line Items]
Regulatory Assets		166
Commonwealth Edison Co [Member] | Fair value of long-term debt
Regulatory Assets [Line Items]
Regulatory Assets		0
Commonwealth Edison Co [Member] | Fair value of PHI's unamortized energy contracts
Regulatory Assets [Line Items]
Regulatory Assets		0
Commonwealth Edison Co [Member] | Asset retirement obligations
Regulatory Assets [Line Items]
Regulatory Assets	79	73
Commonwealth Edison Co [Member] | MGP remediation costs
Regulatory Assets [Line Items]
Regulatory Assets	309	273
Commonwealth Edison Co [Member] | Renewable Energy Program [Member]
Regulatory Assets [Line Items]
Regulatory Assets		256
Commonwealth Edison Co [Member] | Electric Energy and Natural Gas Costs
Regulatory Assets [Line Items]
Regulatory Assets		0
Commonwealth Edison Co [Member] | Under Recovered Transmission Costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets	6	6
Commonwealth Edison Co [Member] | Energy efficiency and demand response programs
Regulatory Assets [Line Items]
Regulatory Assets		0
Commonwealth Edison Co [Member] | Merger integration costs
Regulatory Assets [Line Items]
Regulatory Assets		0
Commonwealth Edison Co [Member] | Under-recovered revenue decoupling
Regulatory Assets [Line Items]
Regulatory Assets		0
Commonwealth Edison Co [Member] | Securitized stranded costs
Regulatory Assets [Line Items]
Regulatory Assets		0
Commonwealth Edison Co [Member] | Removal costs
Regulatory Assets [Line Items]
Regulatory Assets		0
Commonwealth Edison Co [Member] | DC PLUG charge
Regulatory Assets [Line Items]
Regulatory Assets		0
Commonwealth Edison Co [Member] | Storm Costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets	0	0
Commonwealth Edison Co [Member] | Other
Regulatory Assets [Line Items]
Regulatory Assets		106
PECO Energy Co [Member]
Regulatory Assets [Line Items]
Regulatory Assets		410
Current regulatory assets	81	29
Noncurrent regulatory assets	460	381
PECO Energy Co [Member] | Pension and Other Postretirement Plans Costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets		0
PECO Energy Co [Member] | Pension and Post Retirement Plan Merger Costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets	0	0
PECO Energy Co [Member] | Deferred income taxes
Regulatory Assets [Line Items]
Regulatory Assets		297
PECO Energy Co [Member] | Advanced Metering Infrastructure Deployment Costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets	0	0
PECO Energy Co [Member] | Advanced Metering Infrastructure Legacy Meter Costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets		36
PECO Energy Co [Member] | Advanced Metering Infrastructure Incremental Deployment Costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets	0	0
PECO Energy Co [Member] | Electric Distribution Formula Rate Annual Reconciliations [Member]
Regulatory Assets [Line Items]
Regulatory Assets		0
PECO Energy Co [Member] | Electric Distribution Formula Rate One-time Events [Member]
Regulatory Assets [Line Items]
Regulatory Assets	0	0
PECO Energy Co [Member] | Energy efficiency costs
Regulatory Assets [Line Items]
Regulatory Assets		0
PECO Energy Co [Member] | Fair value of long-term debt
Regulatory Assets [Line Items]
Regulatory Assets		0
PECO Energy Co [Member] | Fair value of PHI's unamortized energy contracts
Regulatory Assets [Line Items]
Regulatory Assets	0	0
PECO Energy Co [Member] | Asset retirement obligations
Regulatory Assets [Line Items]
Regulatory Assets		22
PECO Energy Co [Member] | MGP remediation costs
Regulatory Assets [Line Items]
Regulatory Assets		22
PECO Energy Co [Member] | Renewable Energy Program [Member]
Regulatory Assets [Line Items]
Regulatory Assets		0
PECO Energy Co [Member] | Electric Energy and Natural Gas Costs
Regulatory Assets [Line Items]
Regulatory Assets		1
PECO Energy Co [Member] | Under Recovered Transmission Costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets		0
PECO Energy Co [Member] | Energy efficiency and demand response programs
Regulatory Assets [Line Items]
Regulatory Assets		1
PECO Energy Co [Member] | Merger integration costs
Regulatory Assets [Line Items]
Regulatory Assets		0
PECO Energy Co [Member] | Under-recovered revenue decoupling
Regulatory Assets [Line Items]
Regulatory Assets		0
PECO Energy Co [Member] | Securitized stranded costs
Regulatory Assets [Line Items]
Regulatory Assets		0
PECO Energy Co [Member] | Removal costs
Regulatory Assets [Line Items]
Regulatory Assets		0
PECO Energy Co [Member] | DC PLUG charge
Regulatory Assets [Line Items]
Regulatory Assets		0
PECO Energy Co [Member] | Storm Costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets	0	0
PECO Energy Co [Member] | Other
Regulatory Assets [Line Items]
Regulatory Assets		31
Baltimore Gas and Electric Company [Member]
Regulatory Assets [Line Items]
Regulatory Assets		571
Current regulatory assets	177	174
Noncurrent regulatory assets	398	397
Baltimore Gas and Electric Company [Member] | Pension and Other Postretirement Plans Costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets	0	0
Baltimore Gas and Electric Company [Member] | Pension and Post Retirement Plan Merger Costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets	0	0
Baltimore Gas and Electric Company [Member] | Deferred income taxes
Regulatory Assets [Line Items]
Regulatory Assets		0
Baltimore Gas and Electric Company [Member] | Advanced Metering Infrastructure Deployment Costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets		129
Baltimore Gas and Electric Company [Member] | Advanced Metering Infrastructure Legacy Meter Costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets	48	53	$ 56
Baltimore Gas and Electric Company [Member] | Advanced Metering Infrastructure Incremental Deployment Costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets	32	32
Baltimore Gas and Electric Company [Member] | Electric Distribution Formula Rate Annual Reconciliations [Member]
Regulatory Assets [Line Items]
Regulatory Assets	0	0
Baltimore Gas and Electric Company [Member] | Electric Distribution Formula Rate One-time Events [Member]
Regulatory Assets [Line Items]
Regulatory Assets	0	0
Baltimore Gas and Electric Company [Member] | Energy efficiency costs
Regulatory Assets [Line Items]
Regulatory Assets	0	0
Baltimore Gas and Electric Company [Member] | Fair value of long-term debt
Regulatory Assets [Line Items]
Regulatory Assets	0	0
Baltimore Gas and Electric Company [Member] | Fair value of PHI's unamortized energy contracts
Regulatory Assets [Line Items]
Regulatory Assets	0	0
Baltimore Gas and Electric Company [Member] | Asset retirement obligations
Regulatory Assets [Line Items]
Regulatory Assets		14
Baltimore Gas and Electric Company [Member] | MGP remediation costs
Regulatory Assets [Line Items]
Regulatory Assets		0
Baltimore Gas and Electric Company [Member] | Renewable Energy Program [Member]
Regulatory Assets [Line Items]
Regulatory Assets		0
Baltimore Gas and Electric Company [Member] | Electric Energy and Natural Gas Costs
Regulatory Assets [Line Items]
Regulatory Assets		16
Baltimore Gas and Electric Company [Member] | Under Recovered Transmission Costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets	4	7
Baltimore Gas and Electric Company [Member] | Energy efficiency and demand response programs
Regulatory Assets [Line Items]
Regulatory Assets		285
Baltimore Gas and Electric Company [Member] | Merger integration costs
Regulatory Assets [Line Items]
Regulatory Assets		6
Baltimore Gas and Electric Company [Member] | Under-recovered revenue decoupling
Regulatory Assets [Line Items]
Regulatory Assets		14
Baltimore Gas and Electric Company [Member] | Securitized stranded costs
Regulatory Assets [Line Items]
Regulatory Assets		0
Baltimore Gas and Electric Company [Member] | Removal costs
Regulatory Assets [Line Items]
Regulatory Assets	0	0
Baltimore Gas and Electric Company [Member] | DC PLUG charge
Regulatory Assets [Line Items]
Regulatory Assets	0	0
Baltimore Gas and Electric Company [Member] | Storm Costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets	0	0
Baltimore Gas and Electric Company [Member] | Other
Regulatory Assets [Line Items]
Regulatory Assets		15
Pepco Holdings LLC [Member]
Regulatory Assets [Line Items]
Regulatory Assets		3,047
Current regulatory assets	489	554
Noncurrent regulatory assets	2,312	2,493
Pepco Holdings LLC [Member] | Pension and Other Postretirement Plans Costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets	0	0
Pepco Holdings LLC [Member] | Pension and Post Retirement Plan Merger Costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets	0	0
Pepco Holdings LLC [Member] | Deferred income taxes
Regulatory Assets [Line Items]
Regulatory Assets	10	9
Pepco Holdings LLC [Member] | Advanced Metering Infrastructure Deployment Costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets	89	101
Pepco Holdings LLC [Member] | Advanced Metering Infrastructure Legacy Meter Costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets	120	134
Pepco Holdings LLC [Member] | Advanced Metering Infrastructure Incremental Deployment Costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets	0	0
Pepco Holdings LLC [Member] | Electric Distribution Formula Rate Annual Reconciliations [Member]
Regulatory Assets [Line Items]
Regulatory Assets	0	0
Pepco Holdings LLC [Member] | Electric Distribution Formula Rate One-time Events [Member]
Regulatory Assets [Line Items]
Regulatory Assets	0	0
Pepco Holdings LLC [Member] | Energy efficiency costs
Regulatory Assets [Line Items]
Regulatory Assets	0	0
Pepco Holdings LLC [Member] | Fair value of long-term debt
Regulatory Assets [Line Items]
Regulatory Assets	569	619
Pepco Holdings LLC [Member] | Fair value of PHI's unamortized energy contracts
Regulatory Assets [Line Items]
Regulatory Assets	561	750
Pepco Holdings LLC [Member] | Asset retirement obligations
Regulatory Assets [Line Items]
Regulatory Assets	1	0
Pepco Holdings LLC [Member] | MGP remediation costs
Regulatory Assets [Line Items]
Regulatory Assets	0	0
Pepco Holdings LLC [Member] | Renewable Energy Program [Member]
Regulatory Assets [Line Items]
Regulatory Assets	0	2
Pepco Holdings LLC [Member] | Electric Energy and Natural Gas Costs
Regulatory Assets [Line Items]
Regulatory Assets	93	30
Pepco Holdings LLC [Member] | Under Recovered Transmission Costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets	31	22
Pepco Holdings LLC [Member] | Energy efficiency and demand response programs
Regulatory Assets [Line Items]
Regulatory Assets	255	310
Pepco Holdings LLC [Member] | Merger integration costs
Regulatory Assets [Line Items]
Regulatory Assets	39	39
Pepco Holdings LLC [Member] | Under-recovered revenue decoupling
Regulatory Assets [Line Items]
Regulatory Assets	57	41
Pepco Holdings LLC [Member] | Securitized stranded costs
Regulatory Assets [Line Items]
Regulatory Assets	50	79
Pepco Holdings LLC [Member] | Removal costs
Regulatory Assets [Line Items]
Regulatory Assets	564	529
Pepco Holdings LLC [Member] | DC PLUG charge
Regulatory Assets [Line Items]
Regulatory Assets	159	190
Pepco Holdings LLC [Member] | Storm Costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets	41	27
Pepco Holdings LLC [Member] | Other
Regulatory Assets [Line Items]
Regulatory Assets	162	165
Potomac Electric Power Company [Member]
Regulatory Assets [Line Items]
Regulatory Assets		891
Current regulatory assets	270	213
Noncurrent regulatory assets	643	678
Potomac Electric Power Company [Member] | Pension and Other Postretirement Plans Costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets	0	0
Potomac Electric Power Company [Member] | Pension and Post Retirement Plan Merger Costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets	0	0
Potomac Electric Power Company [Member] | Deferred income taxes
Regulatory Assets [Line Items]
Regulatory Assets	10	9
Potomac Electric Power Company [Member] | Advanced Metering Infrastructure Deployment Costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets	50	58
Potomac Electric Power Company [Member] | Advanced Metering Infrastructure Legacy Meter Costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets	90	100
Potomac Electric Power Company [Member] | Advanced Metering Infrastructure Incremental Deployment Costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets	0	0
Potomac Electric Power Company [Member] | Electric Distribution Formula Rate Annual Reconciliations [Member]
Regulatory Assets [Line Items]
Regulatory Assets	0	0
Potomac Electric Power Company [Member] | Electric Distribution Formula Rate One-time Events [Member]
Regulatory Assets [Line Items]
Regulatory Assets	0	0
Potomac Electric Power Company [Member] | Energy efficiency costs
Regulatory Assets [Line Items]
Regulatory Assets	0	0
Potomac Electric Power Company [Member] | Fair value of long-term debt
Regulatory Assets [Line Items]
Regulatory Assets	0	0
Potomac Electric Power Company [Member] | Fair value of PHI's unamortized energy contracts
Regulatory Assets [Line Items]
Regulatory Assets	0	0
Potomac Electric Power Company [Member] | Asset retirement obligations
Regulatory Assets [Line Items]
Regulatory Assets	1	0
Potomac Electric Power Company [Member] | MGP remediation costs
Regulatory Assets [Line Items]
Regulatory Assets	0	0
Potomac Electric Power Company [Member] | Renewable Energy Program [Member]
Regulatory Assets [Line Items]
Regulatory Assets	0	0
Potomac Electric Power Company [Member] | Electric Energy and Natural Gas Costs
Regulatory Assets [Line Items]
Regulatory Assets	84	8
Potomac Electric Power Company [Member] | Under Recovered Transmission Costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets	10	3
Potomac Electric Power Company [Member] | Energy efficiency and demand response programs
Regulatory Assets [Line Items]
Regulatory Assets	188	229
Potomac Electric Power Company [Member] | Merger integration costs
Regulatory Assets [Line Items]
Regulatory Assets	18	20
Potomac Electric Power Company [Member] | Under-recovered revenue decoupling
Regulatory Assets [Line Items]
Regulatory Assets	57	38
Potomac Electric Power Company [Member] | Securitized stranded costs
Regulatory Assets [Line Items]
Regulatory Assets	0	0
Potomac Electric Power Company [Member] | Removal costs
Regulatory Assets [Line Items]
Regulatory Assets	158	150
Potomac Electric Power Company [Member] | DC PLUG charge
Regulatory Assets [Line Items]
Regulatory Assets	159	190
Potomac Electric Power Company [Member] | Storm Costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets	9	7
Potomac Electric Power Company [Member] | Other
Regulatory Assets [Line Items]
Regulatory Assets	79	79
Delmarva Power & Light Company [Member]
Regulatory Assets [Line Items]
Regulatory Assets		314
Current regulatory assets	59	69
Noncurrent regulatory assets	231	245
Delmarva Power & Light Company [Member] | Pension and Other Postretirement Plans Costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets	0	0
Delmarva Power & Light Company [Member] | Pension and Post Retirement Plan Merger Costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets	0	0
Delmarva Power & Light Company [Member] | Deferred income taxes
Regulatory Assets [Line Items]
Regulatory Assets	0	0
Delmarva Power & Light Company [Member] | Advanced Metering Infrastructure Deployment Costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets	39	43
Delmarva Power & Light Company [Member] | Advanced Metering Infrastructure Legacy Meter Costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets	30	34
Delmarva Power & Light Company [Member] | Advanced Metering Infrastructure Incremental Deployment Costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets	0	0
Delmarva Power & Light Company [Member] | Electric Distribution Formula Rate Annual Reconciliations [Member]
Regulatory Assets [Line Items]
Regulatory Assets	0	0
Delmarva Power & Light Company [Member] | Electric Distribution Formula Rate One-time Events [Member]
Regulatory Assets [Line Items]
Regulatory Assets	0	0
Delmarva Power & Light Company [Member] | Energy efficiency costs
Regulatory Assets [Line Items]
Regulatory Assets	0	0
Delmarva Power & Light Company [Member] | Fair value of long-term debt
Regulatory Assets [Line Items]
Regulatory Assets	0	0
Delmarva Power & Light Company [Member] | Fair value of PHI's unamortized energy contracts
Regulatory Assets [Line Items]
Regulatory Assets	0	0
Delmarva Power & Light Company [Member] | Asset retirement obligations
Regulatory Assets [Line Items]
Regulatory Assets	0	0
Delmarva Power & Light Company [Member] | MGP remediation costs
Regulatory Assets [Line Items]
Regulatory Assets	0	0
Delmarva Power & Light Company [Member] | Renewable Energy Program [Member]
Regulatory Assets [Line Items]
Regulatory Assets	0	1
Delmarva Power & Light Company [Member] | Electric Energy and Natural Gas Costs
Regulatory Assets [Line Items]
Regulatory Assets	0	7
Delmarva Power & Light Company [Member] | Under Recovered Transmission Costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets	14	8
Delmarva Power & Light Company [Member] | Energy efficiency and demand response programs
Regulatory Assets [Line Items]
Regulatory Assets	67	81
Delmarva Power & Light Company [Member] | Merger integration costs
Regulatory Assets [Line Items]
Regulatory Assets	11	10
Delmarva Power & Light Company [Member] | Under-recovered revenue decoupling
Regulatory Assets [Line Items]
Regulatory Assets	0	3
Delmarva Power & Light Company [Member] | Securitized stranded costs
Regulatory Assets [Line Items]
Regulatory Assets	0	0
Delmarva Power & Light Company [Member] | Removal costs
Regulatory Assets [Line Items]
Regulatory Assets	97	93
Delmarva Power & Light Company [Member] | DC PLUG charge
Regulatory Assets [Line Items]
Regulatory Assets	0	0
Delmarva Power & Light Company [Member] | Storm Costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets	4	5
Delmarva Power & Light Company [Member] | Other
Regulatory Assets [Line Items]
Regulatory Assets	28	29
Atlantic City Electric Company [Member]
Regulatory Assets [Line Items]
Regulatory Assets		430
Current regulatory assets	40	71
Noncurrent regulatory assets	386	359
Atlantic City Electric Company [Member] | Pension and Other Postretirement Plans Costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets	0	0
Atlantic City Electric Company [Member] | Pension and Post Retirement Plan Merger Costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets	0	0
Atlantic City Electric Company [Member] | Deferred income taxes
Regulatory Assets [Line Items]
Regulatory Assets	0	0
Atlantic City Electric Company [Member] | Advanced Metering Infrastructure Deployment Costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets	0	0
Atlantic City Electric Company [Member] | Advanced Metering Infrastructure Legacy Meter Costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets	0	0
Atlantic City Electric Company [Member] | Advanced Metering Infrastructure Incremental Deployment Costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets	0	0
Atlantic City Electric Company [Member] | Electric Distribution Formula Rate Annual Reconciliations [Member]
Regulatory Assets [Line Items]
Regulatory Assets	0	0
Atlantic City Electric Company [Member] | Electric Distribution Formula Rate One-time Events [Member]
Regulatory Assets [Line Items]
Regulatory Assets	0	0
Atlantic City Electric Company [Member] | Energy efficiency costs
Regulatory Assets [Line Items]
Regulatory Assets	0	0
Atlantic City Electric Company [Member] | Fair value of long-term debt
Regulatory Assets [Line Items]
Regulatory Assets	0	0
Atlantic City Electric Company [Member] | Fair value of PHI's unamortized energy contracts
Regulatory Assets [Line Items]
Regulatory Assets	0	0
Atlantic City Electric Company [Member] | Asset retirement obligations
Regulatory Assets [Line Items]
Regulatory Assets	0	0
Atlantic City Electric Company [Member] | MGP remediation costs
Regulatory Assets [Line Items]
Regulatory Assets	0	0
Atlantic City Electric Company [Member] | Renewable Energy Program [Member]
Regulatory Assets [Line Items]
Regulatory Assets	0	1
Atlantic City Electric Company [Member] | Electric Energy and Natural Gas Costs
Regulatory Assets [Line Items]
Regulatory Assets	9	15
Atlantic City Electric Company [Member] | Under Recovered Transmission Costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets	7	11
Atlantic City Electric Company [Member] | Energy efficiency and demand response programs
Regulatory Assets [Line Items]
Regulatory Assets	0	0
Atlantic City Electric Company [Member] | Merger integration costs
Regulatory Assets [Line Items]
Regulatory Assets	10	9
Atlantic City Electric Company [Member] | Under-recovered revenue decoupling
Regulatory Assets [Line Items]
Regulatory Assets	0	0
Atlantic City Electric Company [Member] | Securitized stranded costs
Regulatory Assets [Line Items]
Regulatory Assets	50	79
Atlantic City Electric Company [Member] | Removal costs
Regulatory Assets [Line Items]
Regulatory Assets	309	286
Atlantic City Electric Company [Member] | DC PLUG charge
Regulatory Assets [Line Items]
Regulatory Assets	0	0
Atlantic City Electric Company [Member] | Storm Costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets	28	15
Atlantic City Electric Company [Member] | Other
Regulatory Assets [Line Items]
Regulatory Assets	$ 13	$ 14