Segment Information Segment Information - Electric and Gas Revenue by Customer Class (Details) - USD ($) $ in Millions		3 Months Ended
		Mar. 31, 2018	Mar. 31, 2017
Revenue, Major Customer [Line Items]
Rate-regulated electric revenues			$ 0
Rate-regulated natural gas revenues			0
Revenues from alternative revenue programs		$ 10	79
Revenues		9,693	8,747
Revenue from Related Parties	[1]	0	0
Operating Segments [Member]
Revenue, Major Customer [Line Items]
Rate-regulated electric revenues	[2]	3,955	3,644
Rate-regulated natural gas revenues	[2]	625	553
Revenues	[2]	9,693	8,747
Commonwealth Edison Co [Member]
Revenue, Major Customer [Line Items]
Rate-regulated electric revenues		1,493	1,279
Rate-regulated natural gas revenues			0
Revenues from alternative revenue programs		5	14
Revenues		1,512	1,298
Revenue from Related Parties		14	5
Commonwealth Edison Co [Member] | Operating Segments [Member]
Revenue, Major Customer [Line Items]
Revenues from alternative revenue programs	[3]	5	14
Revenues	[3]		0
Commonwealth Edison Co [Member] | Rate-Regulated Electric Revenues [Member]
Revenue, Major Customer [Line Items]
Rate-regulated electric revenues	[4]	1,498	1,276
Revenue from Related Parties		14	5
Commonwealth Edison Co [Member] | Rate-Regulated Electric Revenues [Member] | Operating Segments [Member]
Revenue, Major Customer [Line Items]
Rate-regulated electric revenues	[3]	9	8
Commonwealth Edison Co [Member] | Rate-Regulated Electric Revenues [Member] | Residential [Member]
Revenue, Major Customer [Line Items]
Rate-regulated electric revenues		717	611
Commonwealth Edison Co [Member] | Rate-Regulated Electric Revenues [Member] | Small Commercial & Industrial [Member]
Revenue, Major Customer [Line Items]
Rate-regulated electric revenues		385	328
Commonwealth Edison Co [Member] | Rate-Regulated Electric Revenues [Member] | Large Commercial & Industrial [Member]
Revenue, Major Customer [Line Items]
Rate-regulated electric revenues		152	107
Commonwealth Edison Co [Member] | Rate-Regulated Electric Revenues [Member] | Public Authorities & Electric Railroads [Member]
Revenue, Major Customer [Line Items]
Rate-regulated electric revenues		14	12
Commonwealth Edison Co [Member] | Rate-Regulated Electric Revenues [Member] | Other [Member]
Revenue, Major Customer [Line Items]
Rate-regulated electric revenues	[5]	230	218
Commonwealth Edison Co [Member] | Rate-Regulated Natural Gas Revenues [Member]
Revenue, Major Customer [Line Items]
Rate-regulated natural gas revenues	[6]	0	0
Commonwealth Edison Co [Member] | Rate-Regulated Natural Gas Revenues [Member] | Operating Segments [Member]
Revenue, Major Customer [Line Items]
Rate-regulated natural gas revenues	[3]	0	0
Commonwealth Edison Co [Member] | Rate-Regulated Natural Gas Revenues [Member] | Residential [Member]
Revenue, Major Customer [Line Items]
Rate-regulated natural gas revenues		0	0
Commonwealth Edison Co [Member] | Rate-Regulated Natural Gas Revenues [Member] | Small Commercial & Industrial [Member]
Revenue, Major Customer [Line Items]
Rate-regulated natural gas revenues		0	0
Commonwealth Edison Co [Member] | Rate-Regulated Natural Gas Revenues [Member] | Large Commercial & Industrial [Member]
Revenue, Major Customer [Line Items]
Rate-regulated natural gas revenues		0	0
Commonwealth Edison Co [Member] | Rate-Regulated Natural Gas Revenues [Member] | Transportation [Member]
Revenue, Major Customer [Line Items]
Rate-regulated natural gas revenues		0	0
Commonwealth Edison Co [Member] | Rate-Regulated Natural Gas Revenues [Member] | Other [Member]
Revenue, Major Customer [Line Items]
Rate-regulated natural gas revenues	[7]	0	0
Commonwealth Edison Co [Member] | Regulated Operation [Member]
Revenue, Major Customer [Line Items]
Revenues		1,498	1,276
Commonwealth Edison Co [Member] | Other Regulated Revenue [Member]
Revenue, Major Customer [Line Items]
Revenues	[3]	14	22
PECO Energy Co [Member]
Revenue, Major Customer [Line Items]
Rate-regulated electric revenues		633	589
Rate-regulated natural gas revenues		232	206
Revenues from alternative revenue programs		(1)	0
Revenues		866	796
Revenue from Related Parties		2	1
PECO Energy Co [Member] | Operating Segments [Member]
Revenue, Major Customer [Line Items]
Revenues from alternative revenue programs	[3]	(1)	0
Revenues	[3]		0
PECO Energy Co [Member] | Rate-Regulated Electric Revenues [Member]
Revenue, Major Customer [Line Items]
Rate-regulated electric revenues	[4]	632	587
Revenue from Related Parties		2	1
PECO Energy Co [Member] | Rate-Regulated Electric Revenues [Member] | Operating Segments [Member]
Revenue, Major Customer [Line Items]
Rate-regulated electric revenues	[3]	3	3
PECO Energy Co [Member] | Rate-Regulated Electric Revenues [Member] | Residential [Member]
Revenue, Major Customer [Line Items]
Rate-regulated electric revenues		403	382
PECO Energy Co [Member] | Rate-Regulated Electric Revenues [Member] | Small Commercial & Industrial [Member]
Revenue, Major Customer [Line Items]
Rate-regulated electric revenues		101	97
PECO Energy Co [Member] | Rate-Regulated Electric Revenues [Member] | Large Commercial & Industrial [Member]
Revenue, Major Customer [Line Items]
Rate-regulated electric revenues		58	52
PECO Energy Co [Member] | Rate-Regulated Electric Revenues [Member] | Public Authorities & Electric Railroads [Member]
Revenue, Major Customer [Line Items]
Rate-regulated electric revenues		8	8
PECO Energy Co [Member] | Rate-Regulated Electric Revenues [Member] | Other [Member]
Revenue, Major Customer [Line Items]
Rate-regulated electric revenues	[5]	62	48
PECO Energy Co [Member] | Rate-Regulated Natural Gas Revenues [Member]
Revenue, Major Customer [Line Items]
Rate-regulated natural gas revenues	[6]	232	206
Revenue from Related Parties		0	0
PECO Energy Co [Member] | Rate-Regulated Natural Gas Revenues [Member] | Operating Segments [Member]
Revenue, Major Customer [Line Items]
Rate-regulated natural gas revenues	[3]	0	0
PECO Energy Co [Member] | Rate-Regulated Natural Gas Revenues [Member] | Residential [Member]
Revenue, Major Customer [Line Items]
Rate-regulated natural gas revenues		161	142
PECO Energy Co [Member] | Rate-Regulated Natural Gas Revenues [Member] | Small Commercial & Industrial [Member]
Revenue, Major Customer [Line Items]
Rate-regulated natural gas revenues		62	55
PECO Energy Co [Member] | Rate-Regulated Natural Gas Revenues [Member] | Large Commercial & Industrial [Member]
Revenue, Major Customer [Line Items]
Rate-regulated natural gas revenues		1	0
PECO Energy Co [Member] | Rate-Regulated Natural Gas Revenues [Member] | Transportation [Member]
Revenue, Major Customer [Line Items]
Rate-regulated natural gas revenues		6	6
PECO Energy Co [Member] | Rate-Regulated Natural Gas Revenues [Member] | Other [Member]
Revenue, Major Customer [Line Items]
Rate-regulated natural gas revenues	[7]	2	3
PECO Energy Co [Member] | Regulated Operation [Member]
Revenue, Major Customer [Line Items]
Revenues		864	793
PECO Energy Co [Member] | Other Regulated Revenue [Member]
Revenue, Major Customer [Line Items]
Revenues	[3]	2	3
Baltimore Gas and Electric Company [Member]
Revenue, Major Customer [Line Items]
Rate-regulated electric revenues		654	640
Rate-regulated natural gas revenues		330	271
Revenues from alternative revenue programs		(13)	35
Revenues		977	951
Revenue from Related Parties		6	5
Baltimore Gas and Electric Company [Member] | Operating Segments [Member]
Revenue, Major Customer [Line Items]
Revenues from alternative revenue programs	[3]	(13)	35
Revenues	[3]		0
Baltimore Gas and Electric Company [Member] | Rate-Regulated Electric Revenues [Member]
Revenue, Major Customer [Line Items]
Rate-regulated electric revenues	[4]	652	638
Revenue from Related Parties		2	2
Baltimore Gas and Electric Company [Member] | Rate-Regulated Electric Revenues [Member] | Operating Segments [Member]
Revenue, Major Customer [Line Items]
Rate-regulated electric revenues	[3]	4	4
Baltimore Gas and Electric Company [Member] | Rate-Regulated Electric Revenues [Member] | Residential [Member]
Revenue, Major Customer [Line Items]
Rate-regulated electric revenues		393	386
Baltimore Gas and Electric Company [Member] | Rate-Regulated Electric Revenues [Member] | Small Commercial & Industrial [Member]
Revenue, Major Customer [Line Items]
Rate-regulated electric revenues		68	69
Baltimore Gas and Electric Company [Member] | Rate-Regulated Electric Revenues [Member] | Large Commercial & Industrial [Member]
Revenue, Major Customer [Line Items]
Rate-regulated electric revenues		106	108
Baltimore Gas and Electric Company [Member] | Rate-Regulated Electric Revenues [Member] | Public Authorities & Electric Railroads [Member]
Revenue, Major Customer [Line Items]
Rate-regulated electric revenues		7	7
Baltimore Gas and Electric Company [Member] | Rate-Regulated Electric Revenues [Member] | Other [Member]
Revenue, Major Customer [Line Items]
Rate-regulated electric revenues	[5]	78	68
Baltimore Gas and Electric Company [Member] | Rate-Regulated Natural Gas Revenues [Member]
Revenue, Major Customer [Line Items]
Rate-regulated natural gas revenues	[6]	332	273
Revenue from Related Parties		4	3
Baltimore Gas and Electric Company [Member] | Rate-Regulated Natural Gas Revenues [Member] | Operating Segments [Member]
Revenue, Major Customer [Line Items]
Rate-regulated natural gas revenues	[3]	2	1
Baltimore Gas and Electric Company [Member] | Rate-Regulated Natural Gas Revenues [Member] | Residential [Member]
Revenue, Major Customer [Line Items]
Rate-regulated natural gas revenues		224	185
Baltimore Gas and Electric Company [Member] | Rate-Regulated Natural Gas Revenues [Member] | Small Commercial & Industrial [Member]
Revenue, Major Customer [Line Items]
Rate-regulated natural gas revenues		34	30
Baltimore Gas and Electric Company [Member] | Rate-Regulated Natural Gas Revenues [Member] | Large Commercial & Industrial [Member]
Revenue, Major Customer [Line Items]
Rate-regulated natural gas revenues		47	44
Baltimore Gas and Electric Company [Member] | Rate-Regulated Natural Gas Revenues [Member] | Transportation [Member]
Revenue, Major Customer [Line Items]
Rate-regulated natural gas revenues		0	0
Baltimore Gas and Electric Company [Member] | Rate-Regulated Natural Gas Revenues [Member] | Other [Member]
Revenue, Major Customer [Line Items]
Rate-regulated natural gas revenues	[7]	27	14
Baltimore Gas and Electric Company [Member] | Regulated Operation [Member]
Revenue, Major Customer [Line Items]
Revenues		984	911
Baltimore Gas and Electric Company [Member] | Other Regulated Revenue [Member]
Revenue, Major Customer [Line Items]
Revenues	[3]	(7)	40
Pepco Holdings LLC [Member]
Revenue, Major Customer [Line Items]
Rate-regulated electric revenues		1,151	1,067
Rate-regulated natural gas revenues		78	66
Revenues from alternative revenue programs		18	30
Revenues		1,251	1,175
Revenue from Related Parties		4	12
Pepco Holdings LLC [Member] | Operating Segments [Member]
Revenue, Major Customer [Line Items]
Revenues from alternative revenue programs	[3]	18	30
Revenues	[3]		11
Pepco Holdings LLC [Member] | Rate-Regulated Electric Revenues [Member]
Revenue, Major Customer [Line Items]
Rate-regulated electric revenues	[4]	1,154	1,066
Pepco Holdings LLC [Member] | Rate-Regulated Electric Revenues [Member] | Operating Segments [Member]
Revenue, Major Customer [Line Items]
Rate-regulated electric revenues	[3]	1	2
Pepco Holdings LLC [Member] | Rate-Regulated Electric Revenues [Member] | Residential [Member]
Revenue, Major Customer [Line Items]
Rate-regulated electric revenues		610	554
Pepco Holdings LLC [Member] | Rate-Regulated Electric Revenues [Member] | Small Commercial & Industrial [Member]
Revenue, Major Customer [Line Items]
Rate-regulated electric revenues		115	114
Pepco Holdings LLC [Member] | Rate-Regulated Electric Revenues [Member] | Large Commercial & Industrial [Member]
Revenue, Major Customer [Line Items]
Rate-regulated electric revenues		259	257
Pepco Holdings LLC [Member] | Rate-Regulated Electric Revenues [Member] | Public Authorities & Electric Railroads [Member]
Revenue, Major Customer [Line Items]
Rate-regulated electric revenues		14	15
Pepco Holdings LLC [Member] | Rate-Regulated Electric Revenues [Member] | Other [Member]
Revenue, Major Customer [Line Items]
Rate-regulated electric revenues	[5]	156	126
Pepco Holdings LLC [Member] | Rate-Regulated Natural Gas Revenues [Member]
Revenue, Major Customer [Line Items]
Rate-regulated natural gas revenues	[6]	78	66
Pepco Holdings LLC [Member] | Rate-Regulated Natural Gas Revenues [Member] | Operating Segments [Member]
Revenue, Major Customer [Line Items]
Rate-regulated natural gas revenues	[3]	0	0
Pepco Holdings LLC [Member] | Rate-Regulated Natural Gas Revenues [Member] | Residential [Member]
Revenue, Major Customer [Line Items]
Rate-regulated natural gas revenues		47	40
Pepco Holdings LLC [Member] | Rate-Regulated Natural Gas Revenues [Member] | Small Commercial & Industrial [Member]
Revenue, Major Customer [Line Items]
Rate-regulated natural gas revenues		18	17
Pepco Holdings LLC [Member] | Rate-Regulated Natural Gas Revenues [Member] | Large Commercial & Industrial [Member]
Revenue, Major Customer [Line Items]
Rate-regulated natural gas revenues		4	2
Pepco Holdings LLC [Member] | Rate-Regulated Natural Gas Revenues [Member] | Transportation [Member]
Revenue, Major Customer [Line Items]
Rate-regulated natural gas revenues		5	5
Pepco Holdings LLC [Member] | Rate-Regulated Natural Gas Revenues [Member] | Other [Member]
Revenue, Major Customer [Line Items]
Rate-regulated natural gas revenues	[7]	4	2
Pepco Holdings LLC [Member] | Regulated Operation [Member]
Revenue, Major Customer [Line Items]
Revenues		1,232	1,132
Pepco Holdings LLC [Member] | Other Regulated Revenue [Member]
Revenue, Major Customer [Line Items]
Revenues	[3]	19	43
Potomac Electric Power Company [Member]
Revenue, Major Customer [Line Items]
Rate-regulated electric revenues		536	514
Rate-regulated natural gas revenues			0
Revenues from alternative revenue programs		19	15
Revenues		557	530
Revenue from Related Parties		2	1
Potomac Electric Power Company [Member] | Operating Segments [Member]
Revenue, Major Customer [Line Items]
Revenues from alternative revenue programs	[3]	19	15
Revenues	[3]		0
Potomac Electric Power Company [Member] | Rate-Regulated Electric Revenues [Member]
Revenue, Major Customer [Line Items]
Rate-regulated electric revenues	[4]	537	514
Revenue from Related Parties		2	1
Potomac Electric Power Company [Member] | Rate-Regulated Electric Revenues [Member] | Operating Segments [Member]
Revenue, Major Customer [Line Items]
Rate-regulated electric revenues	[3]	1	1
Potomac Electric Power Company [Member] | Rate-Regulated Electric Revenues [Member] | Residential [Member]
Revenue, Major Customer [Line Items]
Rate-regulated electric revenues		259	236
Potomac Electric Power Company [Member] | Rate-Regulated Electric Revenues [Member] | Small Commercial & Industrial [Member]
Revenue, Major Customer [Line Items]
Rate-regulated electric revenues		32	34
Potomac Electric Power Company [Member] | Rate-Regulated Electric Revenues [Member] | Large Commercial & Industrial [Member]
Revenue, Major Customer [Line Items]
Rate-regulated electric revenues		190	188
Potomac Electric Power Company [Member] | Rate-Regulated Electric Revenues [Member] | Public Authorities & Electric Railroads [Member]
Revenue, Major Customer [Line Items]
Rate-regulated electric revenues		7	8
Potomac Electric Power Company [Member] | Rate-Regulated Electric Revenues [Member] | Other [Member]
Revenue, Major Customer [Line Items]
Rate-regulated electric revenues	[5]	49	48
Potomac Electric Power Company [Member] | Rate-Regulated Natural Gas Revenues [Member]
Revenue, Major Customer [Line Items]
Rate-regulated natural gas revenues	[6]	0	0
Potomac Electric Power Company [Member] | Rate-Regulated Natural Gas Revenues [Member] | Operating Segments [Member]
Revenue, Major Customer [Line Items]
Rate-regulated natural gas revenues	[3]	0	0
Potomac Electric Power Company [Member] | Rate-Regulated Natural Gas Revenues [Member] | Residential [Member]
Revenue, Major Customer [Line Items]
Rate-regulated natural gas revenues		0	0
Potomac Electric Power Company [Member] | Rate-Regulated Natural Gas Revenues [Member] | Small Commercial & Industrial [Member]
Revenue, Major Customer [Line Items]
Rate-regulated natural gas revenues		0	0
Potomac Electric Power Company [Member] | Rate-Regulated Natural Gas Revenues [Member] | Large Commercial & Industrial [Member]
Revenue, Major Customer [Line Items]
Rate-regulated natural gas revenues		0	0
Potomac Electric Power Company [Member] | Rate-Regulated Natural Gas Revenues [Member] | Transportation [Member]
Revenue, Major Customer [Line Items]
Rate-regulated natural gas revenues		0	0
Potomac Electric Power Company [Member] | Rate-Regulated Natural Gas Revenues [Member] | Other [Member]
Revenue, Major Customer [Line Items]
Rate-regulated natural gas revenues	[7]	0	0
Potomac Electric Power Company [Member] | Regulated Operation [Member]
Revenue, Major Customer [Line Items]
Revenues		537	514
Potomac Electric Power Company [Member] | Other Regulated Revenue [Member]
Revenue, Major Customer [Line Items]
Revenues	[3]	20	16
Delmarva Power and Light Company [Member]
Revenue, Major Customer [Line Items]
Rate-regulated electric revenues		303	285
Rate-regulated natural gas revenues		78	66
Revenues from alternative revenue programs		1	9
Revenues		384	362
Revenue from Related Parties		2	2
Delmarva Power and Light Company [Member] | Operating Segments [Member]
Revenue, Major Customer [Line Items]
Revenues from alternative revenue programs	[3]	1	9
Revenues	[3]		0
Delmarva Power and Light Company [Member] | Rate-Regulated Electric Revenues [Member]
Revenue, Major Customer [Line Items]
Rate-regulated electric revenues	[4]	305	286
Revenue from Related Parties		2	2
Delmarva Power and Light Company [Member] | Rate-Regulated Electric Revenues [Member] | Operating Segments [Member]
Revenue, Major Customer [Line Items]
Rate-regulated electric revenues	[3]	0	1
Delmarva Power and Light Company [Member] | Rate-Regulated Electric Revenues [Member] | Residential [Member]
Revenue, Major Customer [Line Items]
Rate-regulated electric revenues		191	176
Delmarva Power and Light Company [Member] | Rate-Regulated Electric Revenues [Member] | Small Commercial & Industrial [Member]
Revenue, Major Customer [Line Items]
Rate-regulated electric revenues		46	44
Delmarva Power and Light Company [Member] | Rate-Regulated Electric Revenues [Member] | Large Commercial & Industrial [Member]
Revenue, Major Customer [Line Items]
Rate-regulated electric revenues		23	24
Delmarva Power and Light Company [Member] | Rate-Regulated Electric Revenues [Member] | Public Authorities & Electric Railroads [Member]
Revenue, Major Customer [Line Items]
Rate-regulated electric revenues		4	4
Delmarva Power and Light Company [Member] | Rate-Regulated Electric Revenues [Member] | Other [Member]
Revenue, Major Customer [Line Items]
Rate-regulated electric revenues	[5]	41	38
Delmarva Power and Light Company [Member] | Rate-Regulated Natural Gas Revenues [Member]
Revenue, Major Customer [Line Items]
Rate-regulated natural gas revenues	[6]	78	66
Delmarva Power and Light Company [Member] | Rate-Regulated Natural Gas Revenues [Member] | Operating Segments [Member]
Revenue, Major Customer [Line Items]
Rate-regulated natural gas revenues	[3]	0	0
Delmarva Power and Light Company [Member] | Rate-Regulated Natural Gas Revenues [Member] | Residential [Member]
Revenue, Major Customer [Line Items]
Rate-regulated natural gas revenues		47	40
Delmarva Power and Light Company [Member] | Rate-Regulated Natural Gas Revenues [Member] | Small Commercial & Industrial [Member]
Revenue, Major Customer [Line Items]
Rate-regulated natural gas revenues		18	17
Delmarva Power and Light Company [Member] | Rate-Regulated Natural Gas Revenues [Member] | Large Commercial & Industrial [Member]
Revenue, Major Customer [Line Items]
Rate-regulated natural gas revenues		4	2
Delmarva Power and Light Company [Member] | Rate-Regulated Natural Gas Revenues [Member] | Transportation [Member]
Revenue, Major Customer [Line Items]
Rate-regulated natural gas revenues		5	5
Delmarva Power and Light Company [Member] | Rate-Regulated Natural Gas Revenues [Member] | Other [Member]
Revenue, Major Customer [Line Items]
Rate-regulated natural gas revenues	[7]	4	2
Delmarva Power and Light Company [Member] | Regulated Operation [Member]
Revenue, Major Customer [Line Items]
Revenues		383	352
Delmarva Power and Light Company [Member] | Other Regulated Revenue [Member]
Revenue, Major Customer [Line Items]
Revenues	[3]	1	10
Atlantic City Electric Company [Member]
Revenue, Major Customer [Line Items]
Rate-regulated electric revenues		311	268
Rate-regulated natural gas revenues			0
Revenues from alternative revenue programs		(2)	6
Revenues		310	275
Revenue from Related Parties		1	1
Atlantic City Electric Company [Member] | Operating Segments [Member]
Revenue, Major Customer [Line Items]
Revenues from alternative revenue programs	[3]	(2)	6
Revenues	[3]		0
Atlantic City Electric Company [Member] | Rate-Regulated Electric Revenues [Member]
Revenue, Major Customer [Line Items]
Rate-regulated electric revenues	[4]	312	269
Revenue from Related Parties		1	1
Atlantic City Electric Company [Member] | Rate-Regulated Electric Revenues [Member] | Operating Segments [Member]
Revenue, Major Customer [Line Items]
Rate-regulated electric revenues	[3]	0	0
Atlantic City Electric Company [Member] | Rate-Regulated Electric Revenues [Member] | Residential [Member]
Revenue, Major Customer [Line Items]
Rate-regulated electric revenues		160	142
Atlantic City Electric Company [Member] | Rate-Regulated Electric Revenues [Member] | Small Commercial & Industrial [Member]
Revenue, Major Customer [Line Items]
Rate-regulated electric revenues		37	36
Atlantic City Electric Company [Member] | Rate-Regulated Electric Revenues [Member] | Large Commercial & Industrial [Member]
Revenue, Major Customer [Line Items]
Rate-regulated electric revenues		46	45
Atlantic City Electric Company [Member] | Rate-Regulated Electric Revenues [Member] | Public Authorities & Electric Railroads [Member]
Revenue, Major Customer [Line Items]
Rate-regulated electric revenues		3	3
Atlantic City Electric Company [Member] | Rate-Regulated Electric Revenues [Member] | Other [Member]
Revenue, Major Customer [Line Items]
Rate-regulated electric revenues	[5]	66	43
Atlantic City Electric Company [Member] | Rate-Regulated Natural Gas Revenues [Member]
Revenue, Major Customer [Line Items]
Rate-regulated natural gas revenues	[6]	0	0
Atlantic City Electric Company [Member] | Rate-Regulated Natural Gas Revenues [Member] | Operating Segments [Member]
Revenue, Major Customer [Line Items]
Rate-regulated natural gas revenues	[3]	0	0
Atlantic City Electric Company [Member] | Rate-Regulated Natural Gas Revenues [Member] | Residential [Member]
Revenue, Major Customer [Line Items]
Rate-regulated natural gas revenues		0	0
Atlantic City Electric Company [Member] | Rate-Regulated Natural Gas Revenues [Member] | Small Commercial & Industrial [Member]
Revenue, Major Customer [Line Items]
Rate-regulated natural gas revenues		0	0
Atlantic City Electric Company [Member] | Rate-Regulated Natural Gas Revenues [Member] | Large Commercial & Industrial [Member]
Revenue, Major Customer [Line Items]
Rate-regulated natural gas revenues		0	0
Atlantic City Electric Company [Member] | Rate-Regulated Natural Gas Revenues [Member] | Transportation [Member]
Revenue, Major Customer [Line Items]
Rate-regulated natural gas revenues		0	0
Atlantic City Electric Company [Member] | Rate-Regulated Natural Gas Revenues [Member] | Other [Member]
Revenue, Major Customer [Line Items]
Rate-regulated natural gas revenues	[7]	0	0
Atlantic City Electric Company [Member] | Regulated Operation [Member]
Revenue, Major Customer [Line Items]
Revenues		312	269
Atlantic City Electric Company [Member] | Other Regulated Revenue [Member]
Revenue, Major Customer [Line Items]
Revenues	[3]	$ (2)	$ 6

[1] Intersegment revenues exclude sales to unconsolidated affiliates. The intersegment profit associated with Generation’s sale of certain products and services by and between Exelon’s segments is not eliminated in consolidation due to the recognition of intersegment profit in accordance with regulatory accounting guidance. For Exelon, these amounts are included in Operating revenues in the Consolidated Statements of Operations and Comprehensive Income.

[2] Includes gross utility tax receipts from customers. The offsetting remittance of utility taxes to the governing bodies is recorded in expenses on the Registrants’ Consolidated Statements of Operations and Comprehensive Income. See Note 18 — Supplemental Financial Information for total utility taxes for the three months ended March 31, 2018 and 2017.

[3] Includes late payment charge revenues.

[4] Includes operating revenues from affiliates of $14 million, $2 million, $2 million, $4 million, $2 million, $2 million, and $1 million at ComEd, PECO, BGE, PHI, Pepco, DPL and ACE, respectively, for the three months ended March 31, 2018 and $5 million, $1 million, $2 million, $1 million, $1 million, $2 million, and $1 million at ComEd, PECO, BGE, PHI, Pepco, DPL and ACE, respectively, for the three months ended March 31, 2017.

[5] Includes revenues from transmission revenue from PJM, wholesale electric revenue and mutual assistance revenue.

[6] Includes operating revenues from affiliates of less than $1 million and $4 million at PECO and BGE, respectively, for the three months ended March 31, 2018 and less than $1 million and $3 million at PECO and BGE, respectively, for the three months ended March 31, 2017.

[7] Includes revenues from off-system natural gas sales.