Segment Information - Reconciliation to Consolidated Financial Statements (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021	Dec. 31, 2021
Segment Reporting Information [Line Items]
Revenues	$ 5,327	$ 4,632
Revenue from Related Parties	6	7
Depreciation and Amortization	817	757
Operating Expenses	4,427	3,808
Interest expense, net	338	318
Income (Loss) before income taxes	699	564
Income taxes	218	39
Net income (loss)	598	(264)
Capital expenditures	1,922	2,140
Assets	92,698		$ 133,013
Income (Loss) from Continuing Operations, Net of Tax, Including Portion Attributable to Noncontrolling Interest	481	525
Other Segments
Segment Reporting Information [Line Items]
Assets			86,677
Continuing Operations
Segment Reporting Information [Line Items]
Capital expenditures	1,695	1,746
Pepco Holdings LLC [Member]
Segment Reporting Information [Line Items]
Revenues	1,404	1,244
Revenue from Related Parties	3	3
Income (Loss) before income taxes	137	136
Income taxes	7	8
Net income (loss)	130	128
Capital expenditures	409	456
Assets	25,636		24,744
Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Revenues	(588)	(501)
Revenue from Related Parties	(587)	(497)
Depreciation and Amortization	0	0
Operating Expenses	(531)	(339)
Interest expense, net	0	0
Income (Loss) before income taxes	(43)	(149)
Income taxes	(10)	(12)
Capital expenditures	0	0
Assets	(4,156)		(8,319)
Income (Loss) from Continuing Operations, Net of Tax, Including Portion Attributable to Noncontrolling Interest	(33)	(137)
Intersegment Eliminations [Member] | Pepco Holdings LLC [Member]
Segment Reporting Information [Line Items]
Revenues	(97)	(96)
Revenue from Related Parties	(97)	(96)
Depreciation and Amortization	0	0
Operating Expenses	(97)	(96)
Interest expense, net	0	0
Income (Loss) before income taxes	0	0
Income taxes	0	0
Net income (loss)	0	0
Capital expenditures	0	0
Assets	(44)		(60)
Commonwealth Edison Co [Member] | Operating Segment [Member]
Segment Reporting Information [Line Items]
Revenues	1,734	1,535
Depreciation and Amortization	321	292
Operating Expenses	1,406	1,210
Interest expense, net	100	96
Income (Loss) before income taxes	240	236
Income taxes	52	39
Capital expenditures	617	613
Assets	37,013		36,470
Income (Loss) from Continuing Operations, Net of Tax, Including Portion Attributable to Noncontrolling Interest	188	197
Commonwealth Edison Co [Member] | Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Revenue from Related Parties	6	6
PECO Energy Co [Member] | Operating Segment [Member]
Segment Reporting Information [Line Items]
Revenues	1,047	889
Depreciation and Amortization	92	86
Operating Expenses	793	679
Interest expense, net	41	38
Income (Loss) before income taxes	220	177
Income taxes	14	10
Capital expenditures	344	295
Assets	14,113		13,824
Income (Loss) from Continuing Operations, Net of Tax, Including Portion Attributable to Noncontrolling Interest	206	167
PECO Energy Co [Member] | Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Revenue from Related Parties	1	2
Baltimore Gas and Electric Company [Member] | Operating Segment [Member]
Segment Reporting Information [Line Items]
Revenues	1,154	974
Depreciation and Amortization	171	152
Operating Expenses	919	752
Interest expense, net	35	34
Income (Loss) before income taxes	207	196
Income taxes	9	(13)
Capital expenditures	303	336
Assets	12,509		12,324
Income (Loss) from Continuing Operations, Net of Tax, Including Portion Attributable to Noncontrolling Interest	198	209
Baltimore Gas and Electric Company [Member] | Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Revenue from Related Parties	7	6
Pepco Holdings LLC [Member] | Operating Segment [Member]
Segment Reporting Information [Line Items]
Revenues	1,404	1,244
Depreciation and Amortization	218	210
Operating Expenses	1,215	1,058
Interest expense, net	69	67
Income (Loss) before income taxes	137	136
Income taxes	7	8
Net income (loss)	130	128
Capital expenditures	409	456
Assets	25,636		24,744
Income (Loss) from Continuing Operations, Net of Tax, Including Portion Attributable to Noncontrolling Interest	130	128
Pepco Holdings LLC [Member] | Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Revenue from Related Parties	3	3
Potomac Electric Power Company [Member] | Operating Segment [Member]
Segment Reporting Information [Line Items]
Revenues	614	553
Depreciation and Amortization	108	102
Operating Expenses	547	466
Interest expense, net	36	34
Income (Loss) before income taxes	44	65
Income taxes	(2)	6
Net income (loss)	46	59
Capital expenditures	218	220
Assets	10,458		9,903
Potomac Electric Power Company [Member] | Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Revenue from Related Parties	1	1
Delmarva Power and Light Company [Member] | Operating Segment [Member]
Segment Reporting Information [Line Items]
Revenues	431	382
Depreciation and Amortization	57	53
Operating Expenses	357	309
Interest expense, net	16	15
Income (Loss) before income taxes	60	61
Income taxes	4	5
Net income (loss)	56	56
Capital expenditures	103	112
Assets	5,573		5,412
Delmarva Power and Light Company [Member] | Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Revenue from Related Parties	1	2
Atlantic City Electric Company [Member] | Operating Segment [Member]
Segment Reporting Information [Line Items]
Revenues	349	310
Depreciation and Amortization	47	47
Operating Expenses	311	282
Interest expense, net	14	15
Income (Loss) before income taxes	27	14
Income taxes	1	0
Net income (loss)	26	14
Capital expenditures	87	123
Assets	4,929		4,556
Atlantic City Electric Company [Member] | Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Revenue from Related Parties	1	1
Corporate and Other [Member] | Corporate, Non-Segment [Member]
Segment Reporting Information [Line Items]
Revenues	576	491
Depreciation and Amortization	15	17
Operating Expenses	625	448
Interest expense, net	93	83
Income (Loss) before income taxes	(62)	(32)
Income taxes	146	7
Capital expenditures	22	46
Assets	7,583		7,634
Income (Loss) from Continuing Operations, Net of Tax, Including Portion Attributable to Noncontrolling Interest	(208)	(39)
Corporate and Other [Member] | Corporate, Non-Segment [Member] | Pepco Holdings LLC [Member]
Segment Reporting Information [Line Items]
Revenues	107	95
Depreciation and Amortization	6	8
Operating Expenses	97	97
Interest expense, net	3	3
Income (Loss) before income taxes	6	(4)
Income taxes	4	(3)
Net income (loss)	2	(1)
Capital expenditures	1	1
Assets	4,720		$ 4,933
Corporate and Other [Member] | Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Revenue from Related Parties	576	487
Corporate and Other [Member] | Intersegment Eliminations [Member] | Pepco Holdings LLC [Member]
Segment Reporting Information [Line Items]
Revenue from Related Parties	97	95
Rate-regulated electric revenues [Member]
Segment Reporting Information [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	4,522	3,991
Rate-regulated electric revenues [Member] | Pepco Holdings LLC [Member]
Segment Reporting Information [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	1,323	1,124
Rate-regulated electric revenues [Member] | Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	(7)	(7)
Rate-regulated electric revenues [Member] | Intersegment Eliminations [Member] | Pepco Holdings LLC [Member]
Segment Reporting Information [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	7	(4)
Rate-regulated electric revenues [Member] | Commonwealth Edison Co [Member] | Operating Segment [Member]
Segment Reporting Information [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	1,734	1,535
Rate-regulated electric revenues [Member] | PECO Energy Co [Member] | Operating Segment [Member]
Segment Reporting Information [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	741	661
Rate-regulated electric revenues [Member] | Baltimore Gas and Electric Company [Member] | Operating Segment [Member]
Segment Reporting Information [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	736	632
Rate-regulated electric revenues [Member] | Pepco Holdings LLC [Member] | Operating Segment [Member]
Segment Reporting Information [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	1,318	1,170
Rate-regulated electric revenues [Member] | Potomac Electric Power Company [Member] | Operating Segment [Member]
Segment Reporting Information [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	614	553
Rate-regulated electric revenues [Member] | Delmarva Power and Light Company [Member] | Operating Segment [Member]
Segment Reporting Information [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	348	311
Rate-regulated electric revenues [Member] | Atlantic City Electric Company [Member] | Operating Segment [Member]
Segment Reporting Information [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	349	310
Rate-regulated electric revenues [Member] | Corporate and Other [Member] | Corporate, Non-Segment [Member]
Segment Reporting Information [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	0	0
Rate-regulated electric revenues [Member] | Corporate and Other [Member] | Corporate, Non-Segment [Member] | Pepco Holdings LLC [Member]
Segment Reporting Information [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	0	0
Rate-regulated natural gas revenues [Member]
Segment Reporting Information [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	805	641
Rate-regulated natural gas revenues [Member] | Pepco Holdings LLC [Member]
Segment Reporting Information [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	83	71
Rate-regulated natural gas revenues [Member] | Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	(2)	0
Rate-regulated natural gas revenues [Member] | Intersegment Eliminations [Member] | Pepco Holdings LLC [Member]
Segment Reporting Information [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	0	0
Rate-regulated natural gas revenues [Member] | Commonwealth Edison Co [Member] | Operating Segment [Member]
Segment Reporting Information [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	0	0
Rate-regulated natural gas revenues [Member] | PECO Energy Co [Member] | Operating Segment [Member]
Segment Reporting Information [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	306	228
Rate-regulated natural gas revenues [Member] | Baltimore Gas and Electric Company [Member] | Operating Segment [Member]
Segment Reporting Information [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	418	342
Rate-regulated natural gas revenues [Member] | Pepco Holdings LLC [Member] | Operating Segment [Member]
Segment Reporting Information [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	83	71
Rate-regulated natural gas revenues [Member] | Potomac Electric Power Company [Member] | Operating Segment [Member]
Segment Reporting Information [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	0	0
Rate-regulated natural gas revenues [Member] | Delmarva Power and Light Company [Member] | Operating Segment [Member]
Segment Reporting Information [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	83	71
Rate-regulated natural gas revenues [Member] | Atlantic City Electric Company [Member] | Operating Segment [Member]
Segment Reporting Information [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	0	0
Rate-regulated natural gas revenues [Member] | Corporate and Other [Member] | Corporate, Non-Segment [Member]
Segment Reporting Information [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	0	0
Rate-regulated natural gas revenues [Member] | Corporate and Other [Member] | Corporate, Non-Segment [Member] | Pepco Holdings LLC [Member]
Segment Reporting Information [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	0	0
Shared service and other revenues [Member]
Segment Reporting Information [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	0	0
Shared service and other revenues [Member] | Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	(579)	(494)
Shared service and other revenues [Member] | Intersegment Eliminations [Member] | Pepco Holdings LLC [Member]
Segment Reporting Information [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	(104)	(92)
Shared service and other revenues [Member] | Commonwealth Edison Co [Member] | Operating Segment [Member]
Segment Reporting Information [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	0	0
Shared service and other revenues [Member] | PECO Energy Co [Member] | Operating Segment [Member]
Segment Reporting Information [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	0	0
Shared service and other revenues [Member] | Baltimore Gas and Electric Company [Member] | Operating Segment [Member]
Segment Reporting Information [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	0	0
Shared service and other revenues [Member] | Pepco Holdings LLC [Member] | Operating Segment [Member]
Segment Reporting Information [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	3	3
Shared service and other revenues [Member] | Potomac Electric Power Company [Member] | Operating Segment [Member]
Segment Reporting Information [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	0	0
Shared service and other revenues [Member] | Delmarva Power and Light Company [Member] | Operating Segment [Member]
Segment Reporting Information [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	0	0
Shared service and other revenues [Member] | Atlantic City Electric Company [Member] | Operating Segment [Member]
Segment Reporting Information [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	0	0
Shared service and other revenues [Member] | Corporate and Other [Member] | Corporate, Non-Segment [Member]
Segment Reporting Information [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	576	491
Shared service and other revenues [Member] | Corporate and Other [Member] | Corporate, Non-Segment [Member] | Pepco Holdings LLC [Member]
Segment Reporting Information [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	$ 107	$ 95