Segment Information - Electric and Gas Revenue by Customer Class (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Revenue, Major Customer [Line Items]
Revenues	$ 4,818	$ 4,239	$ 10,380	$ 9,566
Operating Segment [Member]
Revenue, Major Customer [Line Items]
Revenues	4,818	4,239	10,380	9,566
Operating Segment [Member] | Related Party
Revenue, Major Customer [Line Items]
Revenues from Related Parties	0	0	0	6
Commonwealth Edison Co [Member]
Revenue, Major Customer [Line Items]
Revenues	1,901	1,425	3,568	3,158
Commonwealth Edison Co [Member] | Related Party
Revenue, Major Customer [Line Items]
Revenues from Related Parties	2	3	5	8
Commonwealth Edison Co [Member] | Regulated Operation [Member]
Revenue, Major Customer [Line Items]
Revenues	1,774	1,381	3,283	3,068
Commonwealth Edison Co [Member] | Other Regulated Revenue [Member]
Revenue, Major Customer [Line Items]
Revenues	127	44	285	90
PECO Energy Co [Member]
Revenue, Major Customer [Line Items]
Revenues	828	816	1,940	1,863
PECO Energy Co [Member] | Related Party
Revenue, Major Customer [Line Items]
Revenues from Related Parties	2	1	4	2
PECO Energy Co [Member] | Regulated Operation [Member]
Revenue, Major Customer [Line Items]
Revenues	827	812	1,938	1,849
PECO Energy Co [Member] | Other Regulated Revenue [Member]
Revenue, Major Customer [Line Items]
Revenues	1	4	2	14
Baltimore Gas and Electric Company [Member]
Revenue, Major Customer [Line Items]
Revenues	797	786	2,053	1,940
Baltimore Gas and Electric Company [Member] | Related Party
Revenue, Major Customer [Line Items]
Revenues from Related Parties	2	3	4	10
Baltimore Gas and Electric Company [Member] | Regulated Operation [Member]
Revenue, Major Customer [Line Items]
Revenues	788	800	1,972	1,961
Baltimore Gas and Electric Company [Member] | Other Regulated Revenue [Member]
Revenue, Major Customer [Line Items]
Revenues	9	(14)	81	(21)
Pepco Holdings LLC [Member]
Revenue, Major Customer [Line Items]
Revenues	1,305	1,221	2,841	2,626
Pepco Holdings LLC [Member] | Related Party
Revenue, Major Customer [Line Items]
Revenues from Related Parties	2	2	4	6
Pepco Holdings LLC [Member] | Regulated Operation [Member]
Revenue, Major Customer [Line Items]
Revenues	1,293	1,236	2,760	2,646
Pepco Holdings LLC [Member] | Other Regulated Revenue [Member]
Revenue, Major Customer [Line Items]
Revenues	12	(15)	81	(20)
Potomac Electric Power Company [Member]
Revenue, Major Customer [Line Items]
Revenues	642	581	1,351	1,195
Potomac Electric Power Company [Member] | Related Party
Revenue, Major Customer [Line Items]
Revenues from Related Parties	2	2	3	2
Potomac Electric Power Company [Member] | Regulated Operation [Member]
Revenue, Major Customer [Line Items]
Revenues	633	581	1,300	1,201
Potomac Electric Power Company [Member] | Other Regulated Revenue [Member]
Revenue, Major Customer [Line Items]
Revenues	9	0	51	(6)
Delmarva Power and Light Company [Member]
Revenue, Major Customer [Line Items]
Revenues	349	332	823	763
Delmarva Power and Light Company [Member] | Related Party
Revenue, Major Customer [Line Items]
Revenues from Related Parties	2	2	3	3
Delmarva Power and Light Company [Member] | Regulated Operation [Member]
Revenue, Major Customer [Line Items]
Revenues	345	333	809	765
Delmarva Power and Light Company [Member] | Other Regulated Revenue [Member]
Revenue, Major Customer [Line Items]
Revenues	4	(1)	14	(2)
Atlantic City Electric Company [Member]
Revenue, Major Customer [Line Items]
Revenues	317	309	670	658
Atlantic City Electric Company [Member] | Related Party
Revenue, Major Customer [Line Items]
Revenues from Related Parties	1	1	1	2
Atlantic City Electric Company [Member] | Regulated Operation [Member]
Revenue, Major Customer [Line Items]
Revenues	318	324	654	670
Atlantic City Electric Company [Member] | Other Regulated Revenue [Member]
Revenue, Major Customer [Line Items]
Revenues	(1)	(15)	16	(12)
Rate-regulated electric revenues [Member]
Revenue, Major Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	4,434	3,934	8,896	8,415
Rate-regulated electric revenues [Member] | Operating Segment [Member]
Revenue, Major Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	4,556	3,938	9,264	8,460
Rate-regulated electric revenues [Member] | Commonwealth Edison Co [Member]
Revenue, Major Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	1,781	1,387	3,293	3,075
Rate-regulated electric revenues [Member] | Commonwealth Edison Co [Member] | Regulated Operation [Member]
Revenue, Major Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	1,774	1,381	3,283	3,068
Rate-regulated electric revenues [Member] | Commonwealth Edison Co [Member] | Regulated Operation [Member] | Related Party
Revenue, Major Customer [Line Items]
Revenues from Related Parties	2	3	5	8
Rate-regulated electric revenues [Member] | Commonwealth Edison Co [Member] | Regulated Operation [Member] | Operating Segment [Member]
Revenue, Major Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	9	9	15	15
Rate-regulated electric revenues [Member] | Commonwealth Edison Co [Member] | Regulated Operation [Member] | Residential [Member]
Revenue, Major Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	861	819	1,698	1,675
Rate-regulated electric revenues [Member] | Commonwealth Edison Co [Member] | Regulated Operation [Member] | Small Commercial & Industrial [Member]
Revenue, Major Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	461	312	823	736
Rate-regulated electric revenues [Member] | Commonwealth Edison Co [Member] | Regulated Operation [Member] | Large Commercial & Industrial [Member]
Revenue, Major Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	205	11	290	165
Rate-regulated electric revenues [Member] | Commonwealth Edison Co [Member] | Regulated Operation [Member] | Public Authorities & Electric Railroads [Member]
Revenue, Major Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	13	5	22	20
Rate-regulated electric revenues [Member] | Commonwealth Edison Co [Member] | Regulated Operation [Member] | Other [Member]
Revenue, Major Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	234	234	450	472
Rate-regulated electric revenues [Member] | PECO Energy Co [Member]
Revenue, Major Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	723	707	1,521	1,441
Rate-regulated electric revenues [Member] | PECO Energy Co [Member] | Regulated Operation [Member]
Revenue, Major Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	719	704	1,514	1,436
Rate-regulated electric revenues [Member] | PECO Energy Co [Member] | Regulated Operation [Member] | Related Party
Revenue, Major Customer [Line Items]
Revenues from Related Parties	1	1	3	2
Rate-regulated electric revenues [Member] | PECO Energy Co [Member] | Regulated Operation [Member] | Operating Segment [Member]
Revenue, Major Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	5	4	10	7
Rate-regulated electric revenues [Member] | PECO Energy Co [Member] | Regulated Operation [Member] | Residential [Member]
Revenue, Major Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	444	431	963	918
Rate-regulated electric revenues [Member] | PECO Energy Co [Member] | Regulated Operation [Member] | Small Commercial & Industrial [Member]
Revenue, Major Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	132	126	267	237
Rate-regulated electric revenues [Member] | PECO Energy Co [Member] | Regulated Operation [Member] | Large Commercial & Industrial [Member]
Revenue, Major Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	64	72	129	136
Rate-regulated electric revenues [Member] | PECO Energy Co [Member] | Regulated Operation [Member] | Public Authorities & Electric Railroads [Member]
Revenue, Major Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	8	7	16	15
Rate-regulated electric revenues [Member] | PECO Energy Co [Member] | Regulated Operation [Member] | Other [Member]
Revenue, Major Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	71	68	139	130
Rate-regulated electric revenues [Member] | Baltimore Gas and Electric Company [Member]
Revenue, Major Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	670	642	1,449	1,377
Rate-regulated electric revenues [Member] | Baltimore Gas and Electric Company [Member] | Regulated Operation [Member]
Revenue, Major Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	667	639	1,443	1,373
Rate-regulated electric revenues [Member] | Baltimore Gas and Electric Company [Member] | Regulated Operation [Member] | Related Party
Revenue, Major Customer [Line Items]
Revenues from Related Parties	1	2	2	3
Rate-regulated electric revenues [Member] | Baltimore Gas and Electric Company [Member] | Regulated Operation [Member] | Operating Segment [Member]
Revenue, Major Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	4	4	8	8
Rate-regulated electric revenues [Member] | Baltimore Gas and Electric Company [Member] | Regulated Operation [Member] | Residential [Member]
Revenue, Major Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	363	334	796	752
Rate-regulated electric revenues [Member] | Baltimore Gas and Electric Company [Member] | Regulated Operation [Member] | Small Commercial & Industrial [Member]
Revenue, Major Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	75	70	167	151
Rate-regulated electric revenues [Member] | Baltimore Gas and Electric Company [Member] | Regulated Operation [Member] | Large Commercial & Industrial [Member]
Revenue, Major Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	119	129	268	260
Rate-regulated electric revenues [Member] | Baltimore Gas and Electric Company [Member] | Regulated Operation [Member] | Public Authorities & Electric Railroads [Member]
Revenue, Major Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	7	7	14	14
Rate-regulated electric revenues [Member] | Baltimore Gas and Electric Company [Member] | Regulated Operation [Member] | Other [Member]
Revenue, Major Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	103	99	198	196
Rate-regulated electric revenues [Member] | Pepco Holdings LLC [Member]
Revenue, Major Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	1,265	1,199	2,637	2,522
Rate-regulated electric revenues [Member] | Pepco Holdings LLC [Member] | Regulated Operation [Member]
Revenue, Major Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	1,264	1,199	2,634	2,526
Rate-regulated electric revenues [Member] | Pepco Holdings LLC [Member] | Regulated Operation [Member] | Related Party
Revenue, Major Customer [Line Items]
Revenues from Related Parties	2	2	4	6
Rate-regulated electric revenues [Member] | Pepco Holdings LLC [Member] | Regulated Operation [Member] | Operating Segment [Member]
Revenue, Major Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	3	2	7	2
Rate-regulated electric revenues [Member] | Pepco Holdings LLC [Member] | Regulated Operation [Member] | Residential [Member]
Revenue, Major Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	583	548	1,221	1,200
Rate-regulated electric revenues [Member] | Pepco Holdings LLC [Member] | Regulated Operation [Member] | Small Commercial & Industrial [Member]
Revenue, Major Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	144	140	304	281
Rate-regulated electric revenues [Member] | Pepco Holdings LLC [Member] | Regulated Operation [Member] | Large Commercial & Industrial [Member]
Revenue, Major Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	337	332	714	655
Rate-regulated electric revenues [Member] | Pepco Holdings LLC [Member] | Regulated Operation [Member] | Public Authorities & Electric Railroads [Member]
Revenue, Major Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	15	15	33	31
Rate-regulated electric revenues [Member] | Pepco Holdings LLC [Member] | Regulated Operation [Member] | Other [Member]
Revenue, Major Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	185	164	362	359
Rate-regulated electric revenues [Member] | Potomac Electric Power Company [Member]
Revenue, Major Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	633	580	1,302	1,200
Rate-regulated electric revenues [Member] | Potomac Electric Power Company [Member] | Regulated Operation [Member]
Revenue, Major Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	633	581	1,300	1,201
Rate-regulated electric revenues [Member] | Potomac Electric Power Company [Member] | Regulated Operation [Member] | Related Party
Revenue, Major Customer [Line Items]
Revenues from Related Parties	2	2	3	2
Rate-regulated electric revenues [Member] | Potomac Electric Power Company [Member] | Regulated Operation [Member] | Operating Segment [Member]
Revenue, Major Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	2	1	5	1
Rate-regulated electric revenues [Member] | Potomac Electric Power Company [Member] | Regulated Operation [Member] | Residential [Member]
Revenue, Major Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	267	234	549	509
Rate-regulated electric revenues [Member] | Potomac Electric Power Company [Member] | Regulated Operation [Member] | Small Commercial & Industrial [Member]
Revenue, Major Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	41	35	80	73
Rate-regulated electric revenues [Member] | Potomac Electric Power Company [Member] | Regulated Operation [Member] | Large Commercial & Industrial [Member]
Revenue, Major Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	254	250	535	503
Rate-regulated electric revenues [Member] | Potomac Electric Power Company [Member] | Regulated Operation [Member] | Public Authorities & Electric Railroads [Member]
Revenue, Major Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	7	8	16	16
Rate-regulated electric revenues [Member] | Potomac Electric Power Company [Member] | Regulated Operation [Member] | Other [Member]
Revenue, Major Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	64	54	120	100
Rate-regulated electric revenues [Member] | Delmarva Power and Light Company [Member]
Revenue, Major Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	315	295	682	643
Rate-regulated electric revenues [Member] | Delmarva Power and Light Company [Member] | Regulated Operation [Member]
Revenue, Major Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	316	296	683	645
Rate-regulated electric revenues [Member] | Delmarva Power and Light Company [Member] | Regulated Operation [Member] | Related Party
Revenue, Major Customer [Line Items]
Revenues from Related Parties	2	2	3	3
Rate-regulated electric revenues [Member] | Delmarva Power and Light Company [Member] | Regulated Operation [Member] | Operating Segment [Member]
Revenue, Major Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	1	1	2	1
Rate-regulated electric revenues [Member] | Delmarva Power and Light Company [Member] | Regulated Operation [Member] | Residential [Member]
Revenue, Major Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	161	155	371	362
Rate-regulated electric revenues [Member] | Delmarva Power and Light Company [Member] | Regulated Operation [Member] | Small Commercial & Industrial [Member]
Revenue, Major Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	57	51	119	107
Rate-regulated electric revenues [Member] | Delmarva Power and Light Company [Member] | Regulated Operation [Member] | Large Commercial & Industrial [Member]
Revenue, Major Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	33	30	66	56
Rate-regulated electric revenues [Member] | Delmarva Power and Light Company [Member] | Regulated Operation [Member] | Public Authorities & Electric Railroads [Member]
Revenue, Major Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	4	3	8	7
Rate-regulated electric revenues [Member] | Delmarva Power and Light Company [Member] | Regulated Operation [Member] | Other [Member]
Revenue, Major Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	61	57	119	113
Rate-regulated electric revenues [Member] | Atlantic City Electric Company [Member]
Revenue, Major Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	317	323	653	668
Rate-regulated electric revenues [Member] | Atlantic City Electric Company [Member] | Regulated Operation [Member]
Revenue, Major Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	318	324	654	670
Rate-regulated electric revenues [Member] | Atlantic City Electric Company [Member] | Regulated Operation [Member] | Related Party
Revenue, Major Customer [Line Items]
Revenues from Related Parties	1	1	1	2
Rate-regulated electric revenues [Member] | Atlantic City Electric Company [Member] | Regulated Operation [Member] | Operating Segment [Member]
Revenue, Major Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	0	0	0	0
Rate-regulated electric revenues [Member] | Atlantic City Electric Company [Member] | Regulated Operation [Member] | Residential [Member]
Revenue, Major Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	155	159	301	329
Rate-regulated electric revenues [Member] | Atlantic City Electric Company [Member] | Regulated Operation [Member] | Small Commercial & Industrial [Member]
Revenue, Major Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	46	54	105	101
Rate-regulated electric revenues [Member] | Atlantic City Electric Company [Member] | Regulated Operation [Member] | Large Commercial & Industrial [Member]
Revenue, Major Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	50	52	113	96
Rate-regulated electric revenues [Member] | Atlantic City Electric Company [Member] | Regulated Operation [Member] | Public Authorities & Electric Railroads [Member]
Revenue, Major Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	4	4	9	8
Rate-regulated electric revenues [Member] | Atlantic City Electric Company [Member] | Regulated Operation [Member] | Other [Member]
Revenue, Major Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	63	55	126	136
Rate-regulated natural gas revenues [Member]
Revenue, Major Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	258	307	1,080	1,124
Rate-regulated natural gas revenues [Member] | Operating Segment [Member]
Revenue, Major Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	262	301	1,116	1,106
Rate-regulated natural gas revenues [Member] | Commonwealth Edison Co [Member] | Regulated Operation [Member]
Revenue, Major Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	0	0	0	0
Rate-regulated natural gas revenues [Member] | Commonwealth Edison Co [Member] | Regulated Operation [Member] | Operating Segment [Member]
Revenue, Major Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	0	0	0	0
Rate-regulated natural gas revenues [Member] | Commonwealth Edison Co [Member] | Regulated Operation [Member] | Residential [Member]
Revenue, Major Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	0	0	0	0
Rate-regulated natural gas revenues [Member] | Commonwealth Edison Co [Member] | Regulated Operation [Member] | Small Commercial & Industrial [Member]
Revenue, Major Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	0	0	0	0
Rate-regulated natural gas revenues [Member] | Commonwealth Edison Co [Member] | Regulated Operation [Member] | Large Commercial & Industrial [Member]
Revenue, Major Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	0	0	0	0
Rate-regulated natural gas revenues [Member] | Commonwealth Edison Co [Member] | Regulated Operation [Member] | Transportation [Member]
Revenue, Major Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	0	0	0	0
Rate-regulated natural gas revenues [Member] | Commonwealth Edison Co [Member] | Regulated Operation [Member] | Other [Member]
Revenue, Major Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	0	0	0	0
Rate-regulated natural gas revenues [Member] | PECO Energy Co [Member]
Revenue, Major Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	108	108	425	414
Rate-regulated natural gas revenues [Member] | PECO Energy Co [Member] | Regulated Operation [Member]
Revenue, Major Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	108	108	424	413
Rate-regulated natural gas revenues [Member] | PECO Energy Co [Member] | Regulated Operation [Member] | Related Party
Revenue, Major Customer [Line Items]
Revenues from Related Parties	1	0	1	0
Rate-regulated natural gas revenues [Member] | PECO Energy Co [Member] | Regulated Operation [Member] | Operating Segment [Member]
Revenue, Major Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	1	0	2	1
Rate-regulated natural gas revenues [Member] | PECO Energy Co [Member] | Regulated Operation [Member] | Residential [Member]
Revenue, Major Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	69	71	292	289
Rate-regulated natural gas revenues [Member] | PECO Energy Co [Member] | Regulated Operation [Member] | Small Commercial & Industrial [Member]
Revenue, Major Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	32	29	107	105
Rate-regulated natural gas revenues [Member] | PECO Energy Co [Member] | Regulated Operation [Member] | Large Commercial & Industrial [Member]
Revenue, Major Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	0	0	1	0
Rate-regulated natural gas revenues [Member] | PECO Energy Co [Member] | Regulated Operation [Member] | Transportation [Member]
Revenue, Major Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	5	6	13	14
Rate-regulated natural gas revenues [Member] | PECO Energy Co [Member] | Regulated Operation [Member] | Other [Member]
Revenue, Major Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	2	2	11	5
Rate-regulated natural gas revenues [Member] | Baltimore Gas and Electric Company [Member]
Revenue, Major Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	121	161	530	585
Rate-regulated natural gas revenues [Member] | Baltimore Gas and Electric Company [Member] | Regulated Operation [Member]
Revenue, Major Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	121	161	529	588
Rate-regulated natural gas revenues [Member] | Baltimore Gas and Electric Company [Member] | Regulated Operation [Member] | Related Party
Revenue, Major Customer [Line Items]
Revenues from Related Parties	1	1	2	7
Rate-regulated natural gas revenues [Member] | Baltimore Gas and Electric Company [Member] | Regulated Operation [Member] | Operating Segment [Member]
Revenue, Major Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	1	2	3	3
Rate-regulated natural gas revenues [Member] | Baltimore Gas and Electric Company [Member] | Regulated Operation [Member] | Residential [Member]
Revenue, Major Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	71	96	349	378
Rate-regulated natural gas revenues [Member] | Baltimore Gas and Electric Company [Member] | Regulated Operation [Member] | Small Commercial & Industrial [Member]
Revenue, Major Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	15	18	56	63
Rate-regulated natural gas revenues [Member] | Baltimore Gas and Electric Company [Member] | Regulated Operation [Member] | Large Commercial & Industrial [Member]
Revenue, Major Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	30	35	100	100
Rate-regulated natural gas revenues [Member] | Baltimore Gas and Electric Company [Member] | Regulated Operation [Member] | Transportation [Member]
Revenue, Major Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	0	0	0	0
Rate-regulated natural gas revenues [Member] | Baltimore Gas and Electric Company [Member] | Regulated Operation [Member] | Other [Member]
Revenue, Major Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	5	12	24	47
Rate-regulated natural gas revenues [Member] | Pepco Holdings LLC [Member]
Revenue, Major Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	29	37	126	120
Rate-regulated natural gas revenues [Member] | Pepco Holdings LLC [Member] | Regulated Operation [Member]
Revenue, Major Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	29	37	126	120
Rate-regulated natural gas revenues [Member] | Pepco Holdings LLC [Member] | Regulated Operation [Member] | Operating Segment [Member]
Revenue, Major Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	0	0	0	0
Rate-regulated natural gas revenues [Member] | Pepco Holdings LLC [Member] | Regulated Operation [Member] | Residential [Member]
Revenue, Major Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	16	17	76	68
Rate-regulated natural gas revenues [Member] | Pepco Holdings LLC [Member] | Regulated Operation [Member] | Small Commercial & Industrial [Member]
Revenue, Major Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	7	8	33	29
Rate-regulated natural gas revenues [Member] | Pepco Holdings LLC [Member] | Regulated Operation [Member] | Large Commercial & Industrial [Member]
Revenue, Major Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	1	3	2	6
Rate-regulated natural gas revenues [Member] | Pepco Holdings LLC [Member] | Regulated Operation [Member] | Transportation [Member]
Revenue, Major Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	4	3	8	7
Rate-regulated natural gas revenues [Member] | Pepco Holdings LLC [Member] | Regulated Operation [Member] | Other [Member]
Revenue, Major Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	1	6	7	10
Rate-regulated natural gas revenues [Member] | Potomac Electric Power Company [Member] | Regulated Operation [Member]
Revenue, Major Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	0	0	0	0
Rate-regulated natural gas revenues [Member] | Potomac Electric Power Company [Member] | Regulated Operation [Member] | Operating Segment [Member]
Revenue, Major Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	0	0	0	0
Rate-regulated natural gas revenues [Member] | Potomac Electric Power Company [Member] | Regulated Operation [Member] | Residential [Member]
Revenue, Major Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	0	0	0	0
Rate-regulated natural gas revenues [Member] | Potomac Electric Power Company [Member] | Regulated Operation [Member] | Small Commercial & Industrial [Member]
Revenue, Major Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	0	0	0	0
Rate-regulated natural gas revenues [Member] | Potomac Electric Power Company [Member] | Regulated Operation [Member] | Large Commercial & Industrial [Member]
Revenue, Major Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	0	0	0	0
Rate-regulated natural gas revenues [Member] | Potomac Electric Power Company [Member] | Regulated Operation [Member] | Transportation [Member]
Revenue, Major Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	0	0	0	0
Rate-regulated natural gas revenues [Member] | Potomac Electric Power Company [Member] | Regulated Operation [Member] | Other [Member]
Revenue, Major Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	0	0	0	0
Rate-regulated natural gas revenues [Member] | Delmarva Power and Light Company [Member]
Revenue, Major Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	29	37	126	120
Rate-regulated natural gas revenues [Member] | Delmarva Power and Light Company [Member] | Regulated Operation [Member]
Revenue, Major Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	29	37	126	120
Rate-regulated natural gas revenues [Member] | Delmarva Power and Light Company [Member] | Regulated Operation [Member] | Operating Segment [Member]
Revenue, Major Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	0	0	0	0
Rate-regulated natural gas revenues [Member] | Delmarva Power and Light Company [Member] | Regulated Operation [Member] | Residential [Member]
Revenue, Major Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	16	17	76	68
Rate-regulated natural gas revenues [Member] | Delmarva Power and Light Company [Member] | Regulated Operation [Member] | Small Commercial & Industrial [Member]
Revenue, Major Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	7	8	33	29
Rate-regulated natural gas revenues [Member] | Delmarva Power and Light Company [Member] | Regulated Operation [Member] | Large Commercial & Industrial [Member]
Revenue, Major Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	1	3	2	6
Rate-regulated natural gas revenues [Member] | Delmarva Power and Light Company [Member] | Regulated Operation [Member] | Transportation [Member]
Revenue, Major Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	4	3	8	7
Rate-regulated natural gas revenues [Member] | Delmarva Power and Light Company [Member] | Regulated Operation [Member] | Other [Member]
Revenue, Major Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	1	6	7	10
Rate-regulated natural gas revenues [Member] | Atlantic City Electric Company [Member] | Regulated Operation [Member]
Revenue, Major Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	0	0	0	0
Rate-regulated natural gas revenues [Member] | Atlantic City Electric Company [Member] | Regulated Operation [Member] | Operating Segment [Member]
Revenue, Major Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	0	0	0	0
Rate-regulated natural gas revenues [Member] | Atlantic City Electric Company [Member] | Regulated Operation [Member] | Residential [Member]
Revenue, Major Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	0	0	0	0
Rate-regulated natural gas revenues [Member] | Atlantic City Electric Company [Member] | Regulated Operation [Member] | Small Commercial & Industrial [Member]
Revenue, Major Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	0	0	0	0
Rate-regulated natural gas revenues [Member] | Atlantic City Electric Company [Member] | Regulated Operation [Member] | Large Commercial & Industrial [Member]
Revenue, Major Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	0	0	0	0
Rate-regulated natural gas revenues [Member] | Atlantic City Electric Company [Member] | Regulated Operation [Member] | Transportation [Member]
Revenue, Major Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	0	0	0	0
Rate-regulated natural gas revenues [Member] | Atlantic City Electric Company [Member] | Regulated Operation [Member] | Other [Member]
Revenue, Major Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	0	0	0	0
Alternative revenue programs [Member] | Commonwealth Edison Co [Member] | Regulated Operation [Member] | Operating Segment [Member]
Revenue, Major Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	118	35	270	75
Alternative revenue programs [Member] | PECO Energy Co [Member] | Regulated Operation [Member] | Operating Segment [Member]
Revenue, Major Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	(5)	0	(10)	6
Alternative revenue programs [Member] | Baltimore Gas and Electric Company [Member] | Regulated Operation [Member] | Operating Segment [Member]
Revenue, Major Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	4	(20)	70	(32)
Alternative revenue programs [Member] | Pepco Holdings LLC [Member] | Regulated Operation [Member] | Operating Segment [Member]
Revenue, Major Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	9	(17)	74	(22)
Alternative revenue programs [Member] | Potomac Electric Power Company [Member] | Regulated Operation [Member] | Operating Segment [Member]
Revenue, Major Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	7	(1)	46	(7)
Alternative revenue programs [Member] | Delmarva Power and Light Company [Member] | Regulated Operation [Member] | Operating Segment [Member]
Revenue, Major Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	3	(2)	12	(3)
Alternative revenue programs [Member] | Atlantic City Electric Company [Member] | Regulated Operation [Member] | Operating Segment [Member]
Revenue, Major Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	$ (1)	$ (15)	$ 16	$ (12)