Segment Information Segment Information - Electric and Gas Revenue by Customer Class (Details) - USD ($) $ in Millions		3 Months Ended									9 Months Ended	12 Months Ended
		Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Mar. 23, 2016	Dec. 31, 2016	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Revenue, Major Customer [Line Items]
Operating revenues from affiliates													$ 0	$ 0
Electric operating revenues													0	0
Natural gas operating revenues													0	0
Revenues		$ 8,814	$ 9,403	$ 8,076	$ 9,693	$ 8,384	$ 8,768	$ 7,665	$ 8,747			$ 35,985	33,565	31,366
Revenues from alternative revenue programs												(62)	207	48
Operating Segments [Member]
Revenue, Major Customer [Line Items]
Electric operating revenues	[1]											15,344	14,840	13,869
Natural gas operating revenues	[1]											1,470	1,333	1,166
Revenues	[1]											35,985	33,567	31,365
Operating Segments [Member] | Pepco Holdings LLC [Member]
Revenue, Major Customer [Line Items]
Electric operating revenues	[1],[2],[3]											4,609	4,469
Natural gas operating revenues	[1],[2],[3]											181	161
Revenues	[1],[2],[3]											4,805	4,679
Commonwealth Edison Co [Member]
Revenue, Major Customer [Line Items]
Operating revenues from affiliates												27	15	15
Electric operating revenues												5,884	5,478	5,263
Natural gas operating revenues													0	0
Revenues		1,373	1,598	1,398	1,512	1,309	1,571	1,357	1,298			5,882	5,536	5,254
Revenues from alternative revenue programs												(29)	43	(24)
Commonwealth Edison Co [Member] | Operating Segments [Member]
Revenue, Major Customer [Line Items]
Revenues	[4]												0	0
Revenues from alternative revenue programs												(29)	43	(24)
Commonwealth Edison Co [Member] | Rate-Regulated Electric Revenues [Member]
Revenue, Major Customer [Line Items]
Electric operating revenues	[5]											5,881	5,463	5,248
Commonwealth Edison Co [Member] | Rate-Regulated Electric Revenues [Member] | Residential [Member]
Revenue, Major Customer [Line Items]
Electric operating revenues												2,942	2,715	2,603
Commonwealth Edison Co [Member] | Rate-Regulated Electric Revenues [Member] | Small Commercial & Industrial [Member]
Revenue, Major Customer [Line Items]
Electric operating revenues												1,487	1,363	1,318
Commonwealth Edison Co [Member] | Rate-Regulated Electric Revenues [Member] | Large Commercial & Industrial [Member]
Revenue, Major Customer [Line Items]
Electric operating revenues												538	455	462
Commonwealth Edison Co [Member] | Rate-Regulated Electric Revenues [Member] | Public Authorities & Electric Railroads [Member]
Revenue, Major Customer [Line Items]
Electric operating revenues												47	44	45
Commonwealth Edison Co [Member] | Rate-Regulated Electric Revenues [Member] | Other [Member]
Revenue, Major Customer [Line Items]
Electric operating revenues	[6]											867	886	820
Commonwealth Edison Co [Member] | Rate-Regulated Electric Revenues [Member] | Operating Segments [Member]
Revenue, Major Customer [Line Items]
Electric operating revenues	[7]											30	30	30
Commonwealth Edison Co [Member] | Rate-Regulated Natural Gas Revenues [Member]
Revenue, Major Customer [Line Items]
Natural gas operating revenues	[8]											0	0	0
Commonwealth Edison Co [Member] | Rate-Regulated Natural Gas Revenues [Member] | Residential [Member]
Revenue, Major Customer [Line Items]
Natural gas operating revenues												0	0	0
Commonwealth Edison Co [Member] | Rate-Regulated Natural Gas Revenues [Member] | Small Commercial & Industrial [Member]
Revenue, Major Customer [Line Items]
Natural gas operating revenues												0
Commonwealth Edison Co [Member] | Rate-Regulated Natural Gas Revenues [Member] | Large Commercial & Industrial [Member]
Revenue, Major Customer [Line Items]
Natural gas operating revenues												0	0	0
Commonwealth Edison Co [Member] | Rate-Regulated Natural Gas Revenues [Member] | Other [Member]
Revenue, Major Customer [Line Items]
Natural gas operating revenues	[9]											0	0	0
Commonwealth Edison Co [Member] | Rate-Regulated Natural Gas Revenues [Member] | Transportation [Member]
Revenue, Major Customer [Line Items]
Natural gas operating revenues												0	0	0
Commonwealth Edison Co [Member] | Rate-Regulated Natural Gas Revenues [Member] | Operating Segments [Member]
Revenue, Major Customer [Line Items]
Natural gas operating revenues	[7]											0	0	0
Commonwealth Edison Co [Member] | Regulated Operation [Member]
Revenue, Major Customer [Line Items]
Revenues												5,881	5,463	5,248
Commonwealth Edison Co [Member] | Other Regulated Revenue [Member]
Revenue, Major Customer [Line Items]
Revenues												1	73	6
PECO Energy Co [Member]
Revenue, Major Customer [Line Items]
Operating revenues from affiliates												8	7	8
Electric operating revenues												2,469	2,369	2,524
Natural gas operating revenues												568	494	462
Revenues		765	757	653	866	729	715	630	796			3,038	2,870	2,994
Revenues from alternative revenue programs												(7)	0	0
PECO Energy Co [Member] | Operating Segments [Member]
Revenue, Major Customer [Line Items]
Revenues	[4]												0	0
Revenues from alternative revenue programs												(7)	0	0
PECO Energy Co [Member] | Rate-Regulated Electric Revenues [Member]
Revenue, Major Customer [Line Items]
Electric operating revenues	[5]											2,464	2,363	2,519
PECO Energy Co [Member] | Rate-Regulated Electric Revenues [Member] | Residential [Member]
Revenue, Major Customer [Line Items]
Electric operating revenues												1,566	1,505	1,631
PECO Energy Co [Member] | Rate-Regulated Electric Revenues [Member] | Small Commercial & Industrial [Member]
Revenue, Major Customer [Line Items]
Electric operating revenues												404	401	430
PECO Energy Co [Member] | Rate-Regulated Electric Revenues [Member] | Large Commercial & Industrial [Member]
Revenue, Major Customer [Line Items]
Electric operating revenues												223	223	234
PECO Energy Co [Member] | Rate-Regulated Electric Revenues [Member] | Public Authorities & Electric Railroads [Member]
Revenue, Major Customer [Line Items]
Electric operating revenues												28	30	32
PECO Energy Co [Member] | Rate-Regulated Electric Revenues [Member] | Other [Member]
Revenue, Major Customer [Line Items]
Electric operating revenues	[6]											243	204	192
PECO Energy Co [Member] | Rate-Regulated Electric Revenues [Member] | Operating Segments [Member]
Revenue, Major Customer [Line Items]
Electric operating revenues	[7]											12	12	12
PECO Energy Co [Member] | Rate-Regulated Natural Gas Revenues [Member]
Revenue, Major Customer [Line Items]
Natural gas operating revenues	[8]											568	494	463
PECO Energy Co [Member] | Rate-Regulated Natural Gas Revenues [Member] | Residential [Member]
Revenue, Major Customer [Line Items]
Natural gas operating revenues												395	331	309
PECO Energy Co [Member] | Rate-Regulated Natural Gas Revenues [Member] | Small Commercial & Industrial [Member]
Revenue, Major Customer [Line Items]
Natural gas operating revenues												143	131	121
PECO Energy Co [Member] | Rate-Regulated Natural Gas Revenues [Member] | Large Commercial & Industrial [Member]
Revenue, Major Customer [Line Items]
Natural gas operating revenues												1	1	0
PECO Energy Co [Member] | Rate-Regulated Natural Gas Revenues [Member] | Other [Member]
Revenue, Major Customer [Line Items]
Natural gas operating revenues	[9]											6	8	9
PECO Energy Co [Member] | Rate-Regulated Natural Gas Revenues [Member] | Transportation [Member]
Revenue, Major Customer [Line Items]
Natural gas operating revenues												23	23	24
PECO Energy Co [Member] | Rate-Regulated Natural Gas Revenues [Member] | Operating Segments [Member]
Revenue, Major Customer [Line Items]
Natural gas operating revenues	[7]											1	1	0
PECO Energy Co [Member] | Regulated Operation [Member]
Revenue, Major Customer [Line Items]
Revenues												3,032	2,857	2,982
PECO Energy Co [Member] | Other Regulated Revenue [Member]
Revenue, Major Customer [Line Items]
Revenues												6	13	12
Baltimore Gas and Electric Company [Member]
Revenue, Major Customer [Line Items]
Operating revenues from affiliates												29	16	21
Electric operating revenues												2,428	2,384	2,531
Natural gas operating revenues												738	652	628
Revenues		799	731	662	977	813	738	674	951			3,169	3,176	3,233
Revenues from alternative revenue programs												(26)	124	53
Baltimore Gas and Electric Company [Member] | Operating Segments [Member]
Revenue, Major Customer [Line Items]
Revenues	[4]												0	0
Revenues from alternative revenue programs												(26)	124	53
Baltimore Gas and Electric Company [Member] | Rate-Regulated Electric Revenues [Member]
Revenue, Major Customer [Line Items]
Operating revenues from affiliates												8	5	7
Electric operating revenues	[5]											2,423	2,376	2,525
Baltimore Gas and Electric Company [Member] | Rate-Regulated Electric Revenues [Member] | Residential [Member]
Revenue, Major Customer [Line Items]
Electric operating revenues												1,382	1,365	1,504
Baltimore Gas and Electric Company [Member] | Rate-Regulated Electric Revenues [Member] | Small Commercial & Industrial [Member]
Revenue, Major Customer [Line Items]
Electric operating revenues												257	254	276
Baltimore Gas and Electric Company [Member] | Rate-Regulated Electric Revenues [Member] | Large Commercial & Industrial [Member]
Revenue, Major Customer [Line Items]
Electric operating revenues												429	427	434
Baltimore Gas and Electric Company [Member] | Rate-Regulated Electric Revenues [Member] | Public Authorities & Electric Railroads [Member]
Revenue, Major Customer [Line Items]
Electric operating revenues												28	31	35
Baltimore Gas and Electric Company [Member] | Rate-Regulated Electric Revenues [Member] | Other [Member]
Revenue, Major Customer [Line Items]
Electric operating revenues	[6]											327	299	276
Baltimore Gas and Electric Company [Member] | Rate-Regulated Electric Revenues [Member] | Operating Segments [Member]
Revenue, Major Customer [Line Items]
Electric operating revenues	[7]											13	13	13
Baltimore Gas and Electric Company [Member] | Rate-Regulated Natural Gas Revenues [Member]
Revenue, Major Customer [Line Items]
Operating revenues from affiliates												21	11	14
Natural gas operating revenues	[8]											755	659	640
Baltimore Gas and Electric Company [Member] | Rate-Regulated Natural Gas Revenues [Member] | Residential [Member]
Revenue, Major Customer [Line Items]
Natural gas operating revenues												491	437	432
Baltimore Gas and Electric Company [Member] | Rate-Regulated Natural Gas Revenues [Member] | Small Commercial & Industrial [Member]
Revenue, Major Customer [Line Items]
Natural gas operating revenues												77	75	66
Baltimore Gas and Electric Company [Member] | Rate-Regulated Natural Gas Revenues [Member] | Large Commercial & Industrial [Member]
Revenue, Major Customer [Line Items]
Natural gas operating revenues												124	119	114
Baltimore Gas and Electric Company [Member] | Rate-Regulated Natural Gas Revenues [Member] | Other [Member]
Revenue, Major Customer [Line Items]
Natural gas operating revenues	[9]											63	28	28
Baltimore Gas and Electric Company [Member] | Rate-Regulated Natural Gas Revenues [Member] | Transportation [Member]
Revenue, Major Customer [Line Items]
Natural gas operating revenues												0	0	0
Baltimore Gas and Electric Company [Member] | Rate-Regulated Natural Gas Revenues [Member] | Operating Segments [Member]
Revenue, Major Customer [Line Items]
Natural gas operating revenues	[7]											4	4	2
Baltimore Gas and Electric Company [Member] | Regulated Operation [Member]
Revenue, Major Customer [Line Items]
Revenues												3,178	3,035	3,165
Baltimore Gas and Electric Company [Member] | Other Regulated Revenue [Member]
Revenue, Major Customer [Line Items]
Revenues												(9)	141	68
Pepco Holdings LLC [Member]
Revenue, Major Customer [Line Items]
Operating revenues from affiliates												15	50
Electric operating revenues												4,609	4,428
Natural gas operating revenues												181	161
Revenues		1,117	1,361	1,076	1,251	1,121	1,310	1,074	1,175			4,805	4,679
Revenues from alternative revenue programs												0	40
Pepco Holdings LLC [Member] | Operating Segments [Member]
Revenue, Major Customer [Line Items]
Revenues	[4]												47
Revenues from alternative revenue programs												0	40
Pepco Holdings LLC [Member] | Rate-Regulated Electric Revenues [Member]
Revenue, Major Customer [Line Items]
Operating revenues from affiliates													3	2
Electric operating revenues	[5]											4,614	4,423
Pepco Holdings LLC [Member] | Rate-Regulated Electric Revenues [Member] | Residential [Member]
Revenue, Major Customer [Line Items]
Electric operating revenues												2,351	2,246
Pepco Holdings LLC [Member] | Rate-Regulated Electric Revenues [Member] | Small Commercial & Industrial [Member]
Revenue, Major Customer [Line Items]
Electric operating revenues												488	490
Pepco Holdings LLC [Member] | Rate-Regulated Electric Revenues [Member] | Large Commercial & Industrial [Member]
Revenue, Major Customer [Line Items]
Electric operating revenues												1,124	1,086
Pepco Holdings LLC [Member] | Rate-Regulated Electric Revenues [Member] | Public Authorities & Electric Railroads [Member]
Revenue, Major Customer [Line Items]
Electric operating revenues												58	60
Pepco Holdings LLC [Member] | Rate-Regulated Electric Revenues [Member] | Other [Member]
Revenue, Major Customer [Line Items]
Electric operating revenues	[6]											593	541
Pepco Holdings LLC [Member] | Rate-Regulated Electric Revenues [Member] | Operating Segments [Member]
Revenue, Major Customer [Line Items]
Electric operating revenues	[7]											10	8
Pepco Holdings LLC [Member] | Rate-Regulated Natural Gas Revenues [Member]
Revenue, Major Customer [Line Items]
Natural gas operating revenues	[8]											180	160
Pepco Holdings LLC [Member] | Rate-Regulated Natural Gas Revenues [Member] | Residential [Member]
Revenue, Major Customer [Line Items]
Natural gas operating revenues												99	90
Pepco Holdings LLC [Member] | Rate-Regulated Natural Gas Revenues [Member] | Small Commercial & Industrial [Member]
Revenue, Major Customer [Line Items]
Natural gas operating revenues												44	38
Pepco Holdings LLC [Member] | Rate-Regulated Natural Gas Revenues [Member] | Large Commercial & Industrial [Member]
Revenue, Major Customer [Line Items]
Natural gas operating revenues												8	8
Pepco Holdings LLC [Member] | Rate-Regulated Natural Gas Revenues [Member] | Other [Member]
Revenue, Major Customer [Line Items]
Natural gas operating revenues	[9]											13	9
Pepco Holdings LLC [Member] | Rate-Regulated Natural Gas Revenues [Member] | Transportation [Member]
Revenue, Major Customer [Line Items]
Natural gas operating revenues												16	15
Pepco Holdings LLC [Member] | Rate-Regulated Natural Gas Revenues [Member] | Operating Segments [Member]
Revenue, Major Customer [Line Items]
Natural gas operating revenues	[7]											1	1
Pepco Holdings LLC [Member] | Regulated Operation [Member]
Revenue, Major Customer [Line Items]
Revenues												4,794	4,583
Pepco Holdings LLC [Member] | Other Regulated Revenue [Member]
Revenue, Major Customer [Line Items]
Operating revenues from affiliates												15
Revenues												11	96
Potomac Electric Power Company [Member]
Revenue, Major Customer [Line Items]
Operating revenues from affiliates												6	6	5
Electric operating revenues												2,233	2,126	2,167
Natural gas operating revenues													0	0
Revenues		531	628	523	557	510	604	514	530			2,239	2,158	2,186
Revenues from alternative revenue programs												0	26	14
Potomac Electric Power Company [Member] | Operating Segments [Member]
Revenue, Major Customer [Line Items]
Revenues	[4]												0	0
Revenues from alternative revenue programs												0	26	14
Potomac Electric Power Company [Member] | Rate-Regulated Electric Revenues [Member]
Revenue, Major Customer [Line Items]
Electric operating revenues	[5]											2,232	2,127	2,166
Potomac Electric Power Company [Member] | Rate-Regulated Electric Revenues [Member] | Residential [Member]
Revenue, Major Customer [Line Items]
Electric operating revenues												1,021	964	1,004
Potomac Electric Power Company [Member] | Rate-Regulated Electric Revenues [Member] | Small Commercial & Industrial [Member]
Revenue, Major Customer [Line Items]
Electric operating revenues												140	137	150
Potomac Electric Power Company [Member] | Rate-Regulated Electric Revenues [Member] | Large Commercial & Industrial [Member]
Revenue, Major Customer [Line Items]
Electric operating revenues												846	794	790
Potomac Electric Power Company [Member] | Rate-Regulated Electric Revenues [Member] | Public Authorities & Electric Railroads [Member]
Revenue, Major Customer [Line Items]
Electric operating revenues												32	33	32
Potomac Electric Power Company [Member] | Rate-Regulated Electric Revenues [Member] | Other [Member]
Revenue, Major Customer [Line Items]
Electric operating revenues	[6]											193	199	190
Potomac Electric Power Company [Member] | Rate-Regulated Electric Revenues [Member] | Operating Segments [Member]
Revenue, Major Customer [Line Items]
Electric operating revenues	[7]											7	5	6
Potomac Electric Power Company [Member] | Rate-Regulated Natural Gas Revenues [Member]
Revenue, Major Customer [Line Items]
Natural gas operating revenues	[8]											0	0	0
Potomac Electric Power Company [Member] | Rate-Regulated Natural Gas Revenues [Member] | Residential [Member]
Revenue, Major Customer [Line Items]
Natural gas operating revenues												0	0	0
Potomac Electric Power Company [Member] | Rate-Regulated Natural Gas Revenues [Member] | Small Commercial & Industrial [Member]
Revenue, Major Customer [Line Items]
Natural gas operating revenues												0		0
Potomac Electric Power Company [Member] | Rate-Regulated Natural Gas Revenues [Member] | Large Commercial & Industrial [Member]
Revenue, Major Customer [Line Items]
Natural gas operating revenues												0	0	0
Potomac Electric Power Company [Member] | Rate-Regulated Natural Gas Revenues [Member] | Other [Member]
Revenue, Major Customer [Line Items]
Natural gas operating revenues	[9]											0	0	0
Potomac Electric Power Company [Member] | Rate-Regulated Natural Gas Revenues [Member] | Transportation [Member]
Revenue, Major Customer [Line Items]
Natural gas operating revenues												0	0	0
Potomac Electric Power Company [Member] | Rate-Regulated Natural Gas Revenues [Member] | Operating Segments [Member]
Revenue, Major Customer [Line Items]
Natural gas operating revenues	[7]											0	0	0
Potomac Electric Power Company [Member] | Regulated Operation [Member]
Revenue, Major Customer [Line Items]
Revenues												2,232	2,127	2,166
Potomac Electric Power Company [Member] | Other Regulated Revenue [Member]
Revenue, Major Customer [Line Items]
Revenues												7	31	20
Delmarva Power & Light Company [Member]
Revenue, Major Customer [Line Items]
Operating revenues from affiliates												8	8	7
Electric operating revenues												1,139	1,125	1,128
Natural gas operating revenues												181	161	148
Revenues		331	328	289	384	330	327	282	362			1,332	1,300	1,277
Revenues from alternative revenue programs												4	6	(6)
Delmarva Power & Light Company [Member] | Operating Segments [Member]
Revenue, Major Customer [Line Items]
Revenues	[4]												0	0
Revenues from alternative revenue programs												4	6	(6)
Delmarva Power & Light Company [Member] | Rate-Regulated Electric Revenues [Member]
Revenue, Major Customer [Line Items]
Electric operating revenues	[5]											1,144	1,130	1,132
Delmarva Power & Light Company [Member] | Rate-Regulated Electric Revenues [Member] | Residential [Member]
Revenue, Major Customer [Line Items]
Electric operating revenues												669	663	672
Delmarva Power & Light Company [Member] | Rate-Regulated Electric Revenues [Member] | Small Commercial & Industrial [Member]
Revenue, Major Customer [Line Items]
Electric operating revenues												186	187	188
Delmarva Power & Light Company [Member] | Rate-Regulated Electric Revenues [Member] | Large Commercial & Industrial [Member]
Revenue, Major Customer [Line Items]
Electric operating revenues												100	103	99
Delmarva Power & Light Company [Member] | Rate-Regulated Electric Revenues [Member] | Public Authorities & Electric Railroads [Member]
Revenue, Major Customer [Line Items]
Electric operating revenues												14	14	13
Delmarva Power & Light Company [Member] | Rate-Regulated Electric Revenues [Member] | Other [Member]
Revenue, Major Customer [Line Items]
Electric operating revenues	[6]											175	163	160
Delmarva Power & Light Company [Member] | Rate-Regulated Electric Revenues [Member] | Operating Segments [Member]
Revenue, Major Customer [Line Items]
Electric operating revenues	[7]											3	3	3
Delmarva Power & Light Company [Member] | Rate-Regulated Natural Gas Revenues [Member]
Revenue, Major Customer [Line Items]
Natural gas operating revenues	[8]											180	160	148
Delmarva Power & Light Company [Member] | Rate-Regulated Natural Gas Revenues [Member] | Residential [Member]
Revenue, Major Customer [Line Items]
Natural gas operating revenues												99	90	86
Delmarva Power & Light Company [Member] | Rate-Regulated Natural Gas Revenues [Member] | Small Commercial & Industrial [Member]
Revenue, Major Customer [Line Items]
Natural gas operating revenues												44	38	35
Delmarva Power & Light Company [Member] | Rate-Regulated Natural Gas Revenues [Member] | Large Commercial & Industrial [Member]
Revenue, Major Customer [Line Items]
Natural gas operating revenues												8	8	6
Delmarva Power & Light Company [Member] | Rate-Regulated Natural Gas Revenues [Member] | Other [Member]
Revenue, Major Customer [Line Items]
Natural gas operating revenues	[9]											13	9	8
Delmarva Power & Light Company [Member] | Rate-Regulated Natural Gas Revenues [Member] | Transportation [Member]
Revenue, Major Customer [Line Items]
Natural gas operating revenues												16	15	13
Delmarva Power & Light Company [Member] | Rate-Regulated Natural Gas Revenues [Member] | Operating Segments [Member]
Revenue, Major Customer [Line Items]
Natural gas operating revenues	[7]											1	1	0
Delmarva Power & Light Company [Member] | Regulated Operation [Member]
Revenue, Major Customer [Line Items]
Revenues												1,324	1,290	1,280
Delmarva Power & Light Company [Member] | Other Regulated Revenue [Member]
Revenue, Major Customer [Line Items]
Revenues												8	10	(3)
Atlantic City Electric Company [Member]
Revenue, Major Customer [Line Items]
Operating revenues from affiliates												3	2	3
Electric operating revenues												1,237	1,176	1,245
Natural gas operating revenues													0	0
Revenues		$ 254	$ 406	$ 265	$ 310	$ 271	$ 370	$ 270	$ 275			1,236	1,186	1,257
Revenues from alternative revenue programs												(4)	8	9
Atlantic City Electric Company [Member] | Operating Segments [Member]
Revenue, Major Customer [Line Items]
Revenues	[4]												0	0
Revenues from alternative revenue programs												(4)	8	9
Atlantic City Electric Company [Member] | Rate-Regulated Electric Revenues [Member]
Revenue, Major Customer [Line Items]
Electric operating revenues	[5]											1,240	1,178	1,248
Atlantic City Electric Company [Member] | Rate-Regulated Electric Revenues [Member] | Residential [Member]
Revenue, Major Customer [Line Items]
Electric operating revenues												661	619	664
Atlantic City Electric Company [Member] | Rate-Regulated Electric Revenues [Member] | Small Commercial & Industrial [Member]
Revenue, Major Customer [Line Items]
Electric operating revenues												162	166	183
Atlantic City Electric Company [Member] | Rate-Regulated Electric Revenues [Member] | Large Commercial & Industrial [Member]
Revenue, Major Customer [Line Items]
Electric operating revenues												178	189	201
Atlantic City Electric Company [Member] | Rate-Regulated Electric Revenues [Member] | Public Authorities & Electric Railroads [Member]
Revenue, Major Customer [Line Items]
Electric operating revenues												12	13	13
Atlantic City Electric Company [Member] | Rate-Regulated Electric Revenues [Member] | Other [Member]
Revenue, Major Customer [Line Items]
Electric operating revenues	[6]											227	191	187
Atlantic City Electric Company [Member] | Rate-Regulated Electric Revenues [Member] | Operating Segments [Member]
Revenue, Major Customer [Line Items]
Electric operating revenues	[7]											0	0	0
Atlantic City Electric Company [Member] | Rate-Regulated Natural Gas Revenues [Member]
Revenue, Major Customer [Line Items]
Natural gas operating revenues	[8]											0	0	0
Atlantic City Electric Company [Member] | Rate-Regulated Natural Gas Revenues [Member] | Residential [Member]
Revenue, Major Customer [Line Items]
Natural gas operating revenues												0	0	0
Atlantic City Electric Company [Member] | Rate-Regulated Natural Gas Revenues [Member] | Small Commercial & Industrial [Member]
Revenue, Major Customer [Line Items]
Natural gas operating revenues												0		0
Atlantic City Electric Company [Member] | Rate-Regulated Natural Gas Revenues [Member] | Large Commercial & Industrial [Member]
Revenue, Major Customer [Line Items]
Natural gas operating revenues												0	0	0
Atlantic City Electric Company [Member] | Rate-Regulated Natural Gas Revenues [Member] | Other [Member]
Revenue, Major Customer [Line Items]
Natural gas operating revenues	[9]											0	0	0
Atlantic City Electric Company [Member] | Rate-Regulated Natural Gas Revenues [Member] | Transportation [Member]
Revenue, Major Customer [Line Items]
Natural gas operating revenues												0	0	0
Atlantic City Electric Company [Member] | Rate-Regulated Natural Gas Revenues [Member] | Operating Segments [Member]
Revenue, Major Customer [Line Items]
Natural gas operating revenues	[7]											0	0	0
Atlantic City Electric Company [Member] | Regulated Operation [Member]
Revenue, Major Customer [Line Items]
Revenues												1,240	1,178	1,248
Atlantic City Electric Company [Member] | Other Regulated Revenue [Member]
Revenue, Major Customer [Line Items]
Revenues												(4)	8	$ 9
Successor [Member] | Pepco Holdings LLC [Member]
Revenue, Major Customer [Line Items]
Revenues											$ 3,643
Successor [Member] | Operating Segments [Member] | Pepco Holdings LLC [Member]
Revenue, Major Customer [Line Items]
Electric operating revenues	[1],[2],[3]										3,506
Natural gas operating revenues	[1],[2],[3]										92
Revenues	[1],[2],[3]										3,643
Successor [Member] | Pepco Holdings LLC [Member]
Revenue, Major Customer [Line Items]
Operating revenues from affiliates											45	$ 15	50
Electric operating revenues											3,463		4,428
Natural gas operating revenues											92		161
Revenues											3,643		4,679
Revenues from alternative revenue programs											43		$ 40
Successor [Member] | Pepco Holdings LLC [Member] | Operating Segments [Member]
Revenue, Major Customer [Line Items]
Revenues	[4]										43
Revenues from alternative revenue programs											43
Successor [Member] | Pepco Holdings LLC [Member] | Rate-Regulated Electric Revenues [Member]
Revenue, Major Customer [Line Items]
Electric operating revenues	[5]										3,459
Successor [Member] | Pepco Holdings LLC [Member] | Rate-Regulated Electric Revenues [Member] | Residential [Member]
Revenue, Major Customer [Line Items]
Electric operating revenues											1,779
Successor [Member] | Pepco Holdings LLC [Member] | Rate-Regulated Electric Revenues [Member] | Small Commercial & Industrial [Member]
Revenue, Major Customer [Line Items]
Electric operating revenues											400
Successor [Member] | Pepco Holdings LLC [Member] | Rate-Regulated Electric Revenues [Member] | Large Commercial & Industrial [Member]
Revenue, Major Customer [Line Items]
Electric operating revenues											835
Successor [Member] | Pepco Holdings LLC [Member] | Rate-Regulated Electric Revenues [Member] | Public Authorities & Electric Railroads [Member]
Revenue, Major Customer [Line Items]
Electric operating revenues											45
Successor [Member] | Pepco Holdings LLC [Member] | Rate-Regulated Electric Revenues [Member] | Other [Member]
Revenue, Major Customer [Line Items]
Electric operating revenues	[6]										400
Successor [Member] | Pepco Holdings LLC [Member] | Rate-Regulated Electric Revenues [Member] | Operating Segments [Member]
Revenue, Major Customer [Line Items]
Electric operating revenues	[7]										6
Successor [Member] | Pepco Holdings LLC [Member] | Rate-Regulated Natural Gas Revenues [Member]
Revenue, Major Customer [Line Items]
Natural gas operating revenues	[8]										92
Successor [Member] | Pepco Holdings LLC [Member] | Rate-Regulated Natural Gas Revenues [Member] | Residential [Member]
Revenue, Major Customer [Line Items]
Natural gas operating revenues											50
Successor [Member] | Pepco Holdings LLC [Member] | Rate-Regulated Natural Gas Revenues [Member] | Small Commercial & Industrial [Member]
Revenue, Major Customer [Line Items]
Natural gas operating revenues											21
Successor [Member] | Pepco Holdings LLC [Member] | Rate-Regulated Natural Gas Revenues [Member] | Large Commercial & Industrial [Member]
Revenue, Major Customer [Line Items]
Natural gas operating revenues											4
Successor [Member] | Pepco Holdings LLC [Member] | Rate-Regulated Natural Gas Revenues [Member] | Other [Member]
Revenue, Major Customer [Line Items]
Natural gas operating revenues	[9]										7
Successor [Member] | Pepco Holdings LLC [Member] | Rate-Regulated Natural Gas Revenues [Member] | Transportation [Member]
Revenue, Major Customer [Line Items]
Natural gas operating revenues											10
Successor [Member] | Pepco Holdings LLC [Member] | Rate-Regulated Natural Gas Revenues [Member] | Operating Segments [Member]
Revenue, Major Customer [Line Items]
Natural gas operating revenues	[7]										0
Successor [Member] | Pepco Holdings LLC [Member] | Regulated Operation [Member]
Revenue, Major Customer [Line Items]
Revenues											3,551
Successor [Member] | Pepco Holdings LLC [Member] | Other Regulated Revenue [Member]
Revenue, Major Customer [Line Items]
Revenues											$ 92
Predecessor [Member] | Pepco Holdings LLC [Member]
Revenue, Major Customer [Line Items]
Revenues										$ 1,153
Predecessor [Member] | Operating Segments [Member] | Pepco Holdings LLC [Member]
Revenue, Major Customer [Line Items]
Electric operating revenues	[3]									1,096
Natural gas operating revenues	[3]									57
Revenues	[3]									1,153
Predecessor [Member] | Pepco Holdings LLC [Member]
Revenue, Major Customer [Line Items]
Operating revenues from affiliates										0
Electric operating revenues										1,122
Natural gas operating revenues										57
Revenues										1,153
Revenues from alternative revenue programs										(26)
Predecessor [Member] | Pepco Holdings LLC [Member] | Operating Segments [Member]
Revenue, Major Customer [Line Items]
Revenues	[4]									0
Revenues from alternative revenue programs										(26)
Predecessor [Member] | Pepco Holdings LLC [Member] | Rate-Regulated Electric Revenues [Member]
Revenue, Major Customer [Line Items]
Electric operating revenues	[5]									1,119
Predecessor [Member] | Pepco Holdings LLC [Member] | Rate-Regulated Electric Revenues [Member] | Residential [Member]
Revenue, Major Customer [Line Items]
Electric operating revenues										561
Predecessor [Member] | Pepco Holdings LLC [Member] | Rate-Regulated Electric Revenues [Member] | Small Commercial & Industrial [Member]
Revenue, Major Customer [Line Items]
Electric operating revenues										121
Predecessor [Member] | Pepco Holdings LLC [Member] | Rate-Regulated Electric Revenues [Member] | Large Commercial & Industrial [Member]
Revenue, Major Customer [Line Items]
Electric operating revenues										255
Predecessor [Member] | Pepco Holdings LLC [Member] | Rate-Regulated Electric Revenues [Member] | Public Authorities & Electric Railroads [Member]
Revenue, Major Customer [Line Items]
Electric operating revenues										13
Predecessor [Member] | Pepco Holdings LLC [Member] | Rate-Regulated Electric Revenues [Member] | Other [Member]
Revenue, Major Customer [Line Items]
Electric operating revenues	[6]									169
Predecessor [Member] | Pepco Holdings LLC [Member] | Rate-Regulated Electric Revenues [Member] | Operating Segments [Member]
Revenue, Major Customer [Line Items]
Electric operating revenues	[7]									3
Predecessor [Member] | Pepco Holdings LLC [Member] | Rate-Regulated Natural Gas Revenues [Member]
Revenue, Major Customer [Line Items]
Natural gas operating revenues	[8]									57
Predecessor [Member] | Pepco Holdings LLC [Member] | Rate-Regulated Natural Gas Revenues [Member] | Residential [Member]
Revenue, Major Customer [Line Items]
Natural gas operating revenues										36
Predecessor [Member] | Pepco Holdings LLC [Member] | Rate-Regulated Natural Gas Revenues [Member] | Small Commercial & Industrial [Member]
Revenue, Major Customer [Line Items]
Natural gas operating revenues										14
Predecessor [Member] | Pepco Holdings LLC [Member] | Rate-Regulated Natural Gas Revenues [Member] | Large Commercial & Industrial [Member]
Revenue, Major Customer [Line Items]
Natural gas operating revenues										2
Predecessor [Member] | Pepco Holdings LLC [Member] | Rate-Regulated Natural Gas Revenues [Member] | Other [Member]
Revenue, Major Customer [Line Items]
Natural gas operating revenues	[9]									2
Predecessor [Member] | Pepco Holdings LLC [Member] | Rate-Regulated Natural Gas Revenues [Member] | Transportation [Member]
Revenue, Major Customer [Line Items]
Natural gas operating revenues										3
Predecessor [Member] | Pepco Holdings LLC [Member] | Rate-Regulated Natural Gas Revenues [Member] | Operating Segments [Member]
Revenue, Major Customer [Line Items]
Natural gas operating revenues	[7]									0
Predecessor [Member] | Pepco Holdings LLC [Member] | Regulated Operation [Member]
Revenue, Major Customer [Line Items]
Revenues										1,176
Predecessor [Member] | Pepco Holdings LLC [Member] | Other Regulated Revenue [Member]
Revenue, Major Customer [Line Items]
Revenues										$ (23)

[1] Includes gross utility tax receipts from customers. The offsetting remittance of utility taxes to the governing bodies is recorded in expenses in the Registrants’ Consolidated Statements of Operations and Comprehensive Income. See Note 23 — Supplemental Financial Information for additional information on total utility taxes.

[2] Amounts included represent activity for PHI's successor period, March 24, 2016 through December 31, 2018.

[3] Includes gross utility tax receipts from customers. The offsetting remittance of utility taxes to the governing bodies is recorded in expenses in the Registrants’ Consolidated Statements of Operations and Comprehensive Income. See Note 23 — Supplemental Financial Information for additional information on total utility taxes.

[4] Includes operating revenues from affiliates of $47 million and $43 million at PHI in 2017 and 2016, respectively.

[5] Includes operating revenues from affiliates of $27 million, $7 million, $8 million, $15 million, $6 million, $8 million and $3 million at ComEd, PECO, BGE, PHI, Pepco, DPL and ACE, respectively, in 2018, $15 million, $6 million, $5 million, $3 million, $6 million, $8 million and $2 million at ComEd, PECO, BGE, PHI, Pepco, DPL and ACE, in 2017, and $15 million, $7 million, $7 million, $2 million, $5 million, $7 million and $3 million at ComEd, PECO, BGE, PHI, Pepco, DPL and ACE, respectively, in 2016.

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

[7] Includes late payment charge revenues.

[8] Includes operating revenues from affiliates of $1 million and $21 million at PECO and BGE, respectively, in 2018, $1 million and $11 million at PECO and BGE, respectively, in 2017, and $1 million and $14 million at PECO and BGE, respectively, in 2016.

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