Regulatory Matters Regulatory Matters - Schedule of Regulatory Assets (Details) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016	Mar. 31, 2013	Dec. 31, 2008
Regulatory Assets [Line Items]
Regulatory Assets	$ 9,288	$ 11,388
Current regulatory assets	1,267	1,342
Noncurrent regulatory assets	8,021	10,046
Pension and other postretirement benefits
Regulatory Assets [Line Items]
Regulatory Assets	3,848	4,162
Deferred income taxes
Regulatory Assets [Line Items]
Regulatory Assets	306	2,016
AMI programs
Regulatory Assets [Line Items]
Regulatory Assets	640	701
Electric distribution formula rate
Regulatory Assets [Line Items]
Regulatory Assets	244	188
Energy efficiency costs
Regulatory Assets [Line Items]
Regulatory Assets	166
Debt costs
Regulatory Assets [Line Items]
Regulatory Assets	116	124
Fair value of long-term debt
Regulatory Assets [Line Items]
Regulatory Assets	758	812
Fair value of PHI's unamortized energy contracts
Regulatory Assets [Line Items]
Regulatory Assets	750	1,085
Asset retirement obligations
Regulatory Assets [Line Items]
Regulatory Assets	109	111
MGP remediation costs
Regulatory Assets [Line Items]
Regulatory Assets	295	305
Under-recovered uncollectible accounts
Regulatory Assets [Line Items]
Regulatory Assets	61	56
Renewable energy
Regulatory Assets [Line Items]
Regulatory Assets	258	260
Energy and transmission programs
Regulatory Assets [Line Items]
Regulatory Assets	82	89
Deferred storm costs
Regulatory Assets [Line Items]
Regulatory Assets	27	36
Electric generation-related regulatory asset
Regulatory Assets [Line Items]
Regulatory Assets		10
Rate stabilization deferral
Regulatory Assets [Line Items]
Regulatory Assets		7
Energy efficiency and demand response programs
Regulatory Assets [Line Items]
Regulatory Assets	596	621
Merger integration costs
Regulatory Assets [Line Items]
Regulatory Assets	45	25
Under-recovered revenue decoupling
Regulatory Assets [Line Items]
Regulatory Assets	55	27
COPCO acquisition adjustment
Regulatory Assets [Line Items]
Regulatory Assets	5	8
Workers compensation and long-term disability costs
Regulatory Assets [Line Items]
Regulatory Assets	35	34
Vacation accrual
Regulatory Assets [Line Items]
Regulatory Assets	19	31
Securitized stranded costs
Regulatory Assets [Line Items]
Regulatory Assets	79	138
CAP arrearage
Regulatory Assets [Line Items]
Regulatory Assets	8	11
Removal costs
Regulatory Assets [Line Items]
Regulatory Assets	529	477
DC PLUG charge
Regulatory Assets [Line Items]
Regulatory Assets	190
Other
Regulatory Assets [Line Items]
Regulatory Assets	67	54
Commonwealth Edison Co [Member]
Regulatory Assets [Line Items]
Regulatory Assets	1,279	1,167
Current regulatory assets	225	190
Noncurrent regulatory assets	1,054	977
Commonwealth Edison Co [Member] | Pension and other postretirement benefits
Regulatory Assets [Line Items]
Regulatory Assets	0	0
Commonwealth Edison Co [Member] | Deferred income taxes
Regulatory Assets [Line Items]
Regulatory Assets	0	75
Commonwealth Edison Co [Member] | AMI programs
Regulatory Assets [Line Items]
Regulatory Assets	155	164
Commonwealth Edison Co [Member] | Electric distribution formula rate
Regulatory Assets [Line Items]
Regulatory Assets	244	188
Commonwealth Edison Co [Member] | Energy efficiency costs
Regulatory Assets [Line Items]
Regulatory Assets	166
Commonwealth Edison Co [Member] | Debt costs
Regulatory Assets [Line Items]
Regulatory Assets	37	42
Commonwealth Edison Co [Member] | Fair value of long-term debt
Regulatory Assets [Line Items]
Regulatory Assets	0	0
Commonwealth Edison Co [Member] | Fair value of PHI's unamortized energy contracts
Regulatory Assets [Line Items]
Regulatory Assets	0	0
Commonwealth Edison Co [Member] | Asset retirement obligations
Regulatory Assets [Line Items]
Regulatory Assets	73	76
Commonwealth Edison Co [Member] | MGP remediation costs
Regulatory Assets [Line Items]
Regulatory Assets	273	278
Commonwealth Edison Co [Member] | Under-recovered uncollectible accounts
Regulatory Assets [Line Items]
Regulatory Assets	61	56
Commonwealth Edison Co [Member] | Renewable energy
Regulatory Assets [Line Items]
Regulatory Assets	256	258
Commonwealth Edison Co [Member] | Energy and transmission programs
Regulatory Assets [Line Items]
Regulatory Assets	6	23
Commonwealth Edison Co [Member] | Deferred storm costs
Regulatory Assets [Line Items]
Regulatory Assets	0	0
Commonwealth Edison Co [Member] | Electric generation-related regulatory asset
Regulatory Assets [Line Items]
Regulatory Assets		0
Commonwealth Edison Co [Member] | Rate stabilization deferral
Regulatory Assets [Line Items]
Regulatory Assets		0
Commonwealth Edison Co [Member] | Energy efficiency and demand response programs
Regulatory Assets [Line Items]
Regulatory Assets	0	0
Commonwealth Edison Co [Member] | Merger integration costs
Regulatory Assets [Line Items]
Regulatory Assets	0	0
Commonwealth Edison Co [Member] | Under-recovered revenue decoupling
Regulatory Assets [Line Items]
Regulatory Assets	0	0
Commonwealth Edison Co [Member] | COPCO acquisition adjustment
Regulatory Assets [Line Items]
Regulatory Assets	0	0
Commonwealth Edison Co [Member] | Workers compensation and long-term disability costs
Regulatory Assets [Line Items]
Regulatory Assets	0	0
Commonwealth Edison Co [Member] | Vacation accrual
Regulatory Assets [Line Items]
Regulatory Assets	0	0
Commonwealth Edison Co [Member] | Securitized stranded costs
Regulatory Assets [Line Items]
Regulatory Assets	0	0
Commonwealth Edison Co [Member] | CAP arrearage
Regulatory Assets [Line Items]
Regulatory Assets	0	0
Commonwealth Edison Co [Member] | Removal costs
Regulatory Assets [Line Items]
Regulatory Assets	0	0
Commonwealth Edison Co [Member] | DC PLUG charge
Regulatory Assets [Line Items]
Regulatory Assets	0
Commonwealth Edison Co [Member] | Other
Regulatory Assets [Line Items]
Regulatory Assets	8	7
PECO Energy Co [Member]
Regulatory Assets [Line Items]
Regulatory Assets	410	1,710
Current regulatory assets	29	29
Noncurrent regulatory assets	381	1,681
PECO Energy Co [Member] | Pension and other postretirement benefits
Regulatory Assets [Line Items]
Regulatory Assets	0	0
PECO Energy Co [Member] | Deferred income taxes
Regulatory Assets [Line Items]
Regulatory Assets	297	1,583
PECO Energy Co [Member] | AMI programs
Regulatory Assets [Line Items]
Regulatory Assets	36	49
PECO Energy Co [Member] | Electric distribution formula rate
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] | Debt costs
Regulatory Assets [Line Items]
Regulatory Assets	1	1
PECO Energy Co [Member] | Fair value of long-term debt
Regulatory Assets [Line Items]
Regulatory Assets	0	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	23
PECO Energy Co [Member] | MGP remediation costs
Regulatory Assets [Line Items]
Regulatory Assets	22	26
PECO Energy Co [Member] | Under-recovered uncollectible accounts
Regulatory Assets [Line Items]
Regulatory Assets	0	0
PECO Energy Co [Member] | Renewable energy
Regulatory Assets [Line Items]
Regulatory Assets	0	0
PECO Energy Co [Member] | Energy and transmission programs
Regulatory Assets [Line Items]
Regulatory Assets	1	0
PECO Energy Co [Member] | Deferred storm costs
Regulatory Assets [Line Items]
Regulatory Assets	0	0
PECO Energy Co [Member] | Electric generation-related regulatory asset
Regulatory Assets [Line Items]
Regulatory Assets		0
PECO Energy Co [Member] | Rate stabilization deferral
Regulatory Assets [Line Items]
Regulatory Assets		0
PECO Energy Co [Member] | Energy efficiency and demand response programs
Regulatory Assets [Line Items]
Regulatory Assets	1	1
PECO Energy Co [Member] | Merger integration costs
Regulatory Assets [Line Items]
Regulatory Assets	0	0
PECO Energy Co [Member] | Under-recovered revenue decoupling
Regulatory Assets [Line Items]
Regulatory Assets	0	0
PECO Energy Co [Member] | COPCO acquisition adjustment
Regulatory Assets [Line Items]
Regulatory Assets	0	0
PECO Energy Co [Member] | Workers compensation and long-term disability costs
Regulatory Assets [Line Items]
Regulatory Assets	0	0
PECO Energy Co [Member] | Vacation accrual
Regulatory Assets [Line Items]
Regulatory Assets	6	7
PECO Energy Co [Member] | Securitized stranded costs
Regulatory Assets [Line Items]
Regulatory Assets	0	0
PECO Energy Co [Member] | CAP arrearage
Regulatory Assets [Line Items]
Regulatory Assets	8	11
PECO Energy Co [Member] | Removal costs
Regulatory Assets [Line Items]
Regulatory Assets	0	0
PECO Energy Co [Member] | DC PLUG charge
Regulatory Assets [Line Items]
Regulatory Assets	0
PECO Energy Co [Member] | Other
Regulatory Assets [Line Items]
Regulatory Assets	16	9
Baltimore Gas and Electric Company [Member]
Regulatory Assets [Line Items]
Regulatory Assets	571	712
Current regulatory assets	174	208
Noncurrent regulatory assets	397	504
Baltimore Gas and Electric Company [Member] | Pension and other postretirement benefits
Regulatory Assets [Line Items]
Regulatory Assets	0	0
Baltimore Gas and Electric Company [Member] | Deferred income taxes
Regulatory Assets [Line Items]
Regulatory Assets	0	98
Baltimore Gas and Electric Company [Member] | AMI programs
Regulatory Assets [Line Items]
Regulatory Assets	214	230
Baltimore Gas and Electric Company [Member] | Electric distribution formula rate
Regulatory Assets [Line Items]
Regulatory Assets	0	0
Baltimore Gas and Electric Company [Member] | Energy efficiency costs
Regulatory Assets [Line Items]
Regulatory Assets	0
Baltimore Gas and Electric Company [Member] | Debt costs
Regulatory Assets [Line Items]
Regulatory Assets	11	7
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	12
Baltimore Gas and Electric Company [Member] | MGP remediation costs
Regulatory Assets [Line Items]
Regulatory Assets	0	1
Baltimore Gas and Electric Company [Member] | Under-recovered uncollectible accounts
Regulatory Assets [Line Items]
Regulatory Assets	0	0
Baltimore Gas and Electric Company [Member] | Renewable energy
Regulatory Assets [Line Items]
Regulatory Assets	0	0
Baltimore Gas and Electric Company [Member] | Energy and transmission programs
Regulatory Assets [Line Items]
Regulatory Assets	23	38
Baltimore Gas and Electric Company [Member] | Deferred storm costs
Regulatory Assets [Line Items]
Regulatory Assets	0	1
Baltimore Gas and Electric Company [Member] | Electric generation-related regulatory asset
Regulatory Assets [Line Items]
Regulatory Assets		10
Baltimore Gas and Electric Company [Member] | Rate stabilization deferral
Regulatory Assets [Line Items]
Regulatory Assets		7
Baltimore Gas and Electric Company [Member] | Energy efficiency and demand response programs
Regulatory Assets [Line Items]
Regulatory Assets	285	285
Baltimore Gas and Electric Company [Member] | Merger integration costs
Regulatory Assets [Line Items]
Regulatory Assets	6	10	$ 4
Baltimore Gas and Electric Company [Member] | Under-recovered revenue decoupling
Regulatory Assets [Line Items]
Regulatory Assets	14	3
Baltimore Gas and Electric Company [Member] | COPCO acquisition adjustment
Regulatory Assets [Line Items]
Regulatory Assets	0	0
Baltimore Gas and Electric Company [Member] | Workers compensation and long-term disability costs
Regulatory Assets [Line Items]
Regulatory Assets	0	0
Baltimore Gas and Electric Company [Member] | Vacation accrual
Regulatory Assets [Line Items]
Regulatory Assets	0	0
Baltimore Gas and Electric Company [Member] | Securitized stranded costs
Regulatory Assets [Line Items]
Regulatory Assets	0	0
Baltimore Gas and Electric Company [Member] | CAP arrearage
Regulatory Assets [Line Items]
Regulatory Assets	0	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
Baltimore Gas and Electric Company [Member] | Other
Regulatory Assets [Line Items]
Regulatory Assets	4	10
Pepco Holdings LLC [Member] | Successor [Member]
Regulatory Assets [Line Items]
Regulatory Assets	3,047	3,504
Current regulatory assets	554	653
Noncurrent regulatory assets	2,493	2,851
Pepco Holdings LLC [Member] | Pension and other postretirement benefits | Successor [Member]
Regulatory Assets [Line Items]
Regulatory Assets	0	0
Pepco Holdings LLC [Member] | Deferred income taxes | Successor [Member]
Regulatory Assets [Line Items]
Regulatory Assets	9	260
Pepco Holdings LLC [Member] | AMI programs | Successor [Member]
Regulatory Assets [Line Items]
Regulatory Assets	235	258
Pepco Holdings LLC [Member] | Electric distribution formula rate | Successor [Member]
Regulatory Assets [Line Items]
Regulatory Assets	0	0
Pepco Holdings LLC [Member] | Energy efficiency costs | Successor [Member]
Regulatory Assets [Line Items]
Regulatory Assets	0
Pepco Holdings LLC [Member] | Debt costs | Successor [Member]
Regulatory Assets [Line Items]
Regulatory Assets	73	81
Pepco Holdings LLC [Member] | Fair value of long-term debt | Successor [Member]
Regulatory Assets [Line Items]
Regulatory Assets	619	671
Pepco Holdings LLC [Member] | Fair value of PHI's unamortized energy contracts | Successor [Member]
Regulatory Assets [Line Items]
Regulatory Assets	750	1,085
Pepco Holdings LLC [Member] | Asset retirement obligations | Successor [Member]
Regulatory Assets [Line Items]
Regulatory Assets	0	0
Pepco Holdings LLC [Member] | MGP remediation costs | Successor [Member]
Regulatory Assets [Line Items]
Regulatory Assets	0	0
Pepco Holdings LLC [Member] | Under-recovered uncollectible accounts | Successor [Member]
Regulatory Assets [Line Items]
Regulatory Assets	0	0
Pepco Holdings LLC [Member] | Renewable energy | Successor [Member]
Regulatory Assets [Line Items]
Regulatory Assets	2	2
Pepco Holdings LLC [Member] | Energy and transmission programs | Successor [Member]
Regulatory Assets [Line Items]
Regulatory Assets	52	28
Pepco Holdings LLC [Member] | Deferred storm costs | Successor [Member]
Regulatory Assets [Line Items]
Regulatory Assets	27	35
Pepco Holdings LLC [Member] | Electric generation-related regulatory asset | Successor [Member]
Regulatory Assets [Line Items]
Regulatory Assets		0
Pepco Holdings LLC [Member] | Rate stabilization deferral | Successor [Member]
Regulatory Assets [Line Items]
Regulatory Assets		0
Pepco Holdings LLC [Member] | Energy efficiency and demand response programs | Successor [Member]
Regulatory Assets [Line Items]
Regulatory Assets	310	335
Pepco Holdings LLC [Member] | Merger integration costs | Successor [Member]
Regulatory Assets [Line Items]
Regulatory Assets	39	15
Pepco Holdings LLC [Member] | Under-recovered revenue decoupling | Successor [Member]
Regulatory Assets [Line Items]
Regulatory Assets	41	24
Pepco Holdings LLC [Member] | COPCO acquisition adjustment | Successor [Member]
Regulatory Assets [Line Items]
Regulatory Assets	5	8
Pepco Holdings LLC [Member] | Workers compensation and long-term disability costs | Successor [Member]
Regulatory Assets [Line Items]
Regulatory Assets	35	34
Pepco Holdings LLC [Member] | Vacation accrual | Successor [Member]
Regulatory Assets [Line Items]
Regulatory Assets	13	24
Pepco Holdings LLC [Member] | Securitized stranded costs | Successor [Member]
Regulatory Assets [Line Items]
Regulatory Assets	79	138
Pepco Holdings LLC [Member] | CAP arrearage | Successor [Member]
Regulatory Assets [Line Items]
Regulatory Assets	0	0
Pepco Holdings LLC [Member] | Removal costs | Successor [Member]
Regulatory Assets [Line Items]
Regulatory Assets	529	477
Pepco Holdings LLC [Member] | DC PLUG charge | Successor [Member]
Regulatory Assets [Line Items]
Regulatory Assets	190
Pepco Holdings LLC [Member] | Other | Successor [Member]
Regulatory Assets [Line Items]
Regulatory Assets	39	29
Potomac Electric Power Company [Member]
Regulatory Assets [Line Items]
Regulatory Assets	891	852
Current regulatory assets	213	162
Noncurrent regulatory assets	678	690
Potomac Electric Power Company [Member] | Pension and other postretirement benefits
Regulatory Assets [Line Items]
Regulatory Assets	0	0
Potomac Electric Power Company [Member] | Deferred income taxes
Regulatory Assets [Line Items]
Regulatory Assets	9	171
Potomac Electric Power Company [Member] | AMI programs
Regulatory Assets [Line Items]
Regulatory Assets	158	174
Potomac Electric Power Company [Member] | Electric distribution formula rate
Regulatory Assets [Line Items]
Regulatory Assets	0	0
Potomac Electric Power Company [Member] | Energy efficiency costs
Regulatory Assets [Line Items]
Regulatory Assets	0
Potomac Electric Power Company [Member] | Debt costs
Regulatory Assets [Line Items]
Regulatory Assets	15	17
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	0	0
Potomac Electric Power Company [Member] | MGP remediation costs
Regulatory Assets [Line Items]
Regulatory Assets	0	0
Potomac Electric Power Company [Member] | Under-recovered uncollectible accounts
Regulatory Assets [Line Items]
Regulatory Assets	0	0
Potomac Electric Power Company [Member] | Renewable energy
Regulatory Assets [Line Items]
Regulatory Assets	0	0
Potomac Electric Power Company [Member] | Energy and transmission programs
Regulatory Assets [Line Items]
Regulatory Assets	11	6
Potomac Electric Power Company [Member] | Deferred storm costs
Regulatory Assets [Line Items]
Regulatory Assets	7	12
Potomac Electric Power Company [Member] | Electric generation-related regulatory asset
Regulatory Assets [Line Items]
Regulatory Assets		0
Potomac Electric Power Company [Member] | Rate stabilization deferral
Regulatory Assets [Line Items]
Regulatory Assets		0
Potomac Electric Power Company [Member] | Energy efficiency and demand response programs
Regulatory Assets [Line Items]
Regulatory Assets	229	250
Potomac Electric Power Company [Member] | Merger integration costs
Regulatory Assets [Line Items]
Regulatory Assets	20	11
Potomac Electric Power Company [Member] | Under-recovered revenue decoupling
Regulatory Assets [Line Items]
Regulatory Assets	38	21
Potomac Electric Power Company [Member] | COPCO acquisition adjustment
Regulatory Assets [Line Items]
Regulatory Assets	0	0
Potomac Electric Power Company [Member] | Workers compensation and long-term disability costs
Regulatory Assets [Line Items]
Regulatory Assets	35	34
Potomac Electric Power Company [Member] | Vacation accrual
Regulatory Assets [Line Items]
Regulatory Assets	0	0
Potomac Electric Power Company [Member] | Securitized stranded costs
Regulatory Assets [Line Items]
Regulatory Assets	0	0
Potomac Electric Power Company [Member] | CAP arrearage
Regulatory Assets [Line Items]
Regulatory Assets	0	0
Potomac Electric Power Company [Member] | Removal costs
Regulatory Assets [Line Items]
Regulatory Assets	150	134
Potomac Electric Power Company [Member] | DC PLUG charge
Regulatory Assets [Line Items]
Regulatory Assets	190
Potomac Electric Power Company [Member] | Other
Regulatory Assets [Line Items]
Regulatory Assets	29	22
Delmarva Power and Light Company [Member]
Regulatory Assets [Line Items]
Regulatory Assets	314	348
Current regulatory assets	69	59
Noncurrent regulatory assets	245	289
Delmarva Power and Light Company [Member] | Pension and other postretirement benefits
Regulatory Assets [Line Items]
Regulatory Assets	0	0
Delmarva Power and Light Company [Member] | Deferred income taxes
Regulatory Assets [Line Items]
Regulatory Assets	0	38
Delmarva Power and Light Company [Member] | AMI programs
Regulatory Assets [Line Items]
Regulatory Assets	77	84
Delmarva Power and Light Company [Member] | Electric distribution formula rate
Regulatory Assets [Line Items]
Regulatory Assets	0	0
Delmarva Power and Light Company [Member] | Energy efficiency costs
Regulatory Assets [Line Items]
Regulatory Assets	0
Delmarva Power and Light Company [Member] | Debt costs
Regulatory Assets [Line Items]
Regulatory Assets	8	9
Delmarva Power and Light Company [Member] | Fair value of long-term debt
Regulatory Assets [Line Items]
Regulatory Assets	0	0
Delmarva Power and Light Company [Member] | Fair value of PHI's unamortized energy contracts
Regulatory Assets [Line Items]
Regulatory Assets	0	0
Delmarva Power and Light Company [Member] | Asset retirement obligations
Regulatory Assets [Line Items]
Regulatory Assets	0	0
Delmarva Power and Light Company [Member] | MGP remediation costs
Regulatory Assets [Line Items]
Regulatory Assets	0	0
Delmarva Power and Light Company [Member] | Under-recovered uncollectible accounts
Regulatory Assets [Line Items]
Regulatory Assets	0	0
Delmarva Power and Light Company [Member] | Renewable energy
Regulatory Assets [Line Items]
Regulatory Assets	1	0
Delmarva Power and Light Company [Member] | Energy and transmission programs
Regulatory Assets [Line Items]
Regulatory Assets	15	5
Delmarva Power and Light Company [Member] | Deferred storm costs
Regulatory Assets [Line Items]
Regulatory Assets	5	5
Delmarva Power and Light Company [Member] | Electric generation-related regulatory asset
Regulatory Assets [Line Items]
Regulatory Assets		0
Delmarva Power and Light Company [Member] | Rate stabilization deferral
Regulatory Assets [Line Items]
Regulatory Assets		0
Delmarva Power and Light Company [Member] | Energy efficiency and demand response programs
Regulatory Assets [Line Items]
Regulatory Assets	81	85
Delmarva Power and Light Company [Member] | Merger integration costs
Regulatory Assets [Line Items]
Regulatory Assets	10	4
Delmarva Power and Light Company [Member] | Under-recovered revenue decoupling
Regulatory Assets [Line Items]
Regulatory Assets	3	3
Delmarva Power and Light Company [Member] | COPCO acquisition adjustment
Regulatory Assets [Line Items]
Regulatory Assets	5	8		$ 41
Delmarva Power and Light Company [Member] | Workers compensation and long-term disability costs
Regulatory Assets [Line Items]
Regulatory Assets	0	0
Delmarva Power and Light Company [Member] | Vacation accrual
Regulatory Assets [Line Items]
Regulatory Assets	8	14
Delmarva Power and Light Company [Member] | Securitized stranded costs
Regulatory Assets [Line Items]
Regulatory Assets	0	0
Delmarva Power and Light Company [Member] | CAP arrearage
Regulatory Assets [Line Items]
Regulatory Assets	0	0
Delmarva Power and Light Company [Member] | Removal costs
Regulatory Assets [Line Items]
Regulatory Assets	93	88
Delmarva Power and Light Company [Member] | DC PLUG charge
Regulatory Assets [Line Items]
Regulatory Assets	0
Delmarva Power and Light Company [Member] | Other
Regulatory Assets [Line Items]
Regulatory Assets	8	5
Atlantic City Electric Company [Member]
Regulatory Assets [Line Items]
Regulatory Assets	430	501
Current regulatory assets	71	96
Noncurrent regulatory assets	359	405
Atlantic City Electric Company [Member] | Pension and other postretirement benefits
Regulatory Assets [Line Items]
Regulatory Assets	0	0
Atlantic City Electric Company [Member] | Deferred income taxes
Regulatory Assets [Line Items]
Regulatory Assets	0	51
Atlantic City Electric Company [Member] | AMI programs
Regulatory Assets [Line Items]
Regulatory Assets	0	0
Atlantic City Electric Company [Member] | Electric distribution formula rate
Regulatory Assets [Line Items]
Regulatory Assets	0	0
Atlantic City Electric Company [Member] | Energy efficiency costs
Regulatory Assets [Line Items]
Regulatory Assets	0
Atlantic City Electric Company [Member] | Debt costs
Regulatory Assets [Line Items]
Regulatory Assets	5	6
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] | Under-recovered uncollectible accounts
Regulatory Assets [Line Items]
Regulatory Assets	0	0
Atlantic City Electric Company [Member] | Renewable energy
Regulatory Assets [Line Items]
Regulatory Assets	1	2
Atlantic City Electric Company [Member] | Energy and transmission programs
Regulatory Assets [Line Items]
Regulatory Assets	26	17
Atlantic City Electric Company [Member] | Deferred storm costs
Regulatory Assets [Line Items]
Regulatory Assets	15	18
Atlantic City Electric Company [Member] | Electric generation-related regulatory asset
Regulatory Assets [Line Items]
Regulatory Assets		0
Atlantic City Electric Company [Member] | Rate stabilization deferral
Regulatory Assets [Line Items]
Regulatory Assets		0
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	9	0
Atlantic City Electric Company [Member] | Under-recovered revenue decoupling
Regulatory Assets [Line Items]
Regulatory Assets	0	0
Atlantic City Electric Company [Member] | COPCO acquisition adjustment
Regulatory Assets [Line Items]
Regulatory Assets	0	0
Atlantic City Electric Company [Member] | Workers compensation and long-term disability costs
Regulatory Assets [Line Items]
Regulatory Assets	0	0
Atlantic City Electric Company [Member] | Vacation accrual
Regulatory Assets [Line Items]
Regulatory Assets	5	10
Atlantic City Electric Company [Member] | Securitized stranded costs
Regulatory Assets [Line Items]
Regulatory Assets	79	138
Atlantic City Electric Company [Member] | CAP arrearage
Regulatory Assets [Line Items]
Regulatory Assets	0	0
Atlantic City Electric Company [Member] | Removal costs
Regulatory Assets [Line Items]
Regulatory Assets	286	255
Atlantic City Electric Company [Member] | DC PLUG charge
Regulatory Assets [Line Items]
Regulatory Assets	0
Atlantic City Electric Company [Member] | Other
Regulatory Assets [Line Items]
Regulatory Assets	$ 4	$ 4