Segment Information - Reconciliation to Consolidated Financial Statements (Details) - USD ($) $ in Millions	3 Months Ended				6 Months Ended
	Jun. 30, 2022	Mar. 31, 2022	Jun. 30, 2021	Mar. 31, 2021	Jun. 30, 2022	Jun. 30, 2021	Dec. 31, 2021
Segment Reporting Information [Line Items]
Revenues	$ 4,239		$ 4,020		$ 9,566	$ 8,652
Income (Loss) before income taxes	511		329		1,209	892
Income taxes	46		3		263	42
Net income (loss)	465	$ 598	476	$ (264)	1,063	211
Capital expenditures					3,507	4,040
Assets	92,295				92,295		$ 133,013
Income (Loss) from Continuing Operations, Net of Tax, Including Portion Attributable to Noncontrolling Interest	465		326		946	851
Pepco Holdings LLC [Member]
Segment Reporting Information [Line Items]
Revenues	1,221		1,140		2,626	2,384
Revenue from Related Parties	2		4		6	7
Income (Loss) before income taxes	101		138		238	273
Income taxes	1		(3)		8	5
Net income (loss)	100	$ 130	141	$ 128	230	269
Capital expenditures					776	889
Assets	25,592				25,592		24,744
Operating Segment [Member]
Segment Reporting Information [Line Items]
Revenues	4,239		4,020		9,566	8,652
Revenue from Related Parties	0		5		6	12
Depreciation and Amortization	830		736		1,647	1,494
Operating Expenses	3,543		3,444		7,971	7,252
Interest expense, net	358		324		697	643
Income (Loss) before income taxes	511		329		1,209	892
Income taxes	46		3		263	42
Capital expenditures	1,585		1,563		3,280	3,309
Assets	92,295				92,295		86,669
Income (Loss) from Continuing Operations, Net of Tax, Including Portion Attributable to Noncontrolling Interest	465		326		946	851
Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Revenues	(393)		(536)		(982)	(1,035)
Revenue from Related Parties	(393)		(535)		(981)	(1,033)
Depreciation and Amortization	1		0		0	0
Operating Expenses	(378)		(374)		(909)	(713)
Interest expense, net	1		0		0	0
Income (Loss) before income taxes	(1)		(144)		(45)	(292)
Income taxes	0		(7)		(12)	(20)
Capital expenditures	0		0		0	0
Assets	(4,145)				(4,145)		(8,319)
Income (Loss) from Continuing Operations, Net of Tax, Including Portion Attributable to Noncontrolling Interest	(1)		(137)		(33)	(272)
Intersegment Eliminations [Member] | Pepco Holdings LLC [Member]
Segment Reporting Information [Line Items]
Revenues	(99)		(95)		(195)	(190)
Revenue from Related Parties	(101)		(95)		(196)	(190)
Depreciation and Amortization	0		0		0	0
Operating Expenses	(99)		(95)		(195)	(190)
Interest expense, net	0		0		(1)	0
Income (Loss) before income taxes	0		0		0	0
Income taxes	0		0		0	0
Net income (loss)	0		0		0	0
Capital expenditures	0		0		0	0
Assets	(203)				(203)		(60)
Commonwealth Edison Co [Member] | Operating Segment [Member]
Segment Reporting Information [Line Items]
Revenues	1,425		1,517		3,158	3,052
Depreciation and Amortization	328		296		649	589
Operating Expenses	1,039		1,196		2,444	2,406
Interest expense, net	104		98		204	193
Income (Loss) before income taxes	293		238		534	475
Income taxes	66		46		119	85
Capital expenditures	591		549		1,208	1,162
Assets	37,194				37,194		36,470
Income (Loss) from Continuing Operations, Net of Tax, Including Portion Attributable to Noncontrolling Interest	227		192		415	390
Commonwealth Edison Co [Member] | Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Revenue from Related Parties	3		5		8	11
PECO Energy Co [Member] | Operating Segment [Member]
Segment Reporting Information [Line Items]
Revenues	816		693		1,863	1,582
Depreciation and Amortization	93		87		185	173
Operating Expenses	639		552		1,432	1,231
Interest expense, net	43		42		84	80
Income (Loss) before income taxes	142		106		363	283
Income taxes	9		2		24	12
Capital expenditures	314		282		658	577
Assets	14,216				14,216		13,824
Income (Loss) from Continuing Operations, Net of Tax, Including Portion Attributable to Noncontrolling Interest	133		104		339	271
PECO Energy Co [Member] | Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Revenue from Related Parties	1		2		2	4
Baltimore Gas and Electric Company [Member] | Operating Segment [Member]
Segment Reporting Information [Line Items]
Revenues	786		682		1,940	1,656
Depreciation and Amortization	152		141		322	293
Operating Expenses	717		620		1,636	1,372
Interest expense, net	36		34		71	67
Income (Loss) before income taxes	38		37		244	233
Income taxes	1		(8)		10	(21)
Capital expenditures	275		284		578	620
Assets	13,093				13,093		12,324
Income (Loss) from Continuing Operations, Net of Tax, Including Portion Attributable to Noncontrolling Interest	37		45		234	254
Baltimore Gas and Electric Company [Member] | Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Revenue from Related Parties	3		7		10	13
Pepco Holdings LLC [Member] | Operating Segment [Member]
Segment Reporting Information [Line Items]
Revenues	1,221		1,140		2,626	2,384
Depreciation and Amortization	240		194		459	404
Operating Expenses	1,066		955		2,282	2,013
Interest expense, net	73		67		143	134
Income (Loss) before income taxes	101		138		238	273
Income taxes	1		(3)		8	5
Net income (loss)	100		141		230	269
Capital expenditures	367		433		776	889
Assets	25,592				25,592		24,744
Income (Loss) from Continuing Operations, Net of Tax, Including Portion Attributable to Noncontrolling Interest	100		141		230	269
Pepco Holdings LLC [Member] | Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Revenue from Related Parties	2		4		6	7
Potomac Electric Power Company [Member] | Operating Segment [Member]
Segment Reporting Information [Line Items]
Revenues	581		523		1,195	1,076
Depreciation and Amortization	105		96		213	199
Operating Expenses	487		429		1,034	895
Interest expense, net	38		35		74	69
Income (Loss) before income taxes	69		72		113	137
Income taxes	(1)		(3)		(3)	3
Net income (loss)	70		75		116	134
Capital expenditures	184		219		402	439
Assets	10,226				10,226		9,903
Potomac Electric Power Company [Member] | Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Revenue from Related Parties	2		1		2	3
Delmarva Power and Light Company [Member] | Operating Segment [Member]
Segment Reporting Information [Line Items]
Revenues	332		298		763	680
Depreciation and Amortization	56		51		113	104
Operating Expenses	296		255		653	564
Interest expense, net	17		16		33	30
Income (Loss) before income taxes	23		31		83	92
Income taxes	2		1		6	6
Net income (loss)	21		30		77	86
Capital expenditures	91		99		194	211
Assets	5,742				5,742		5,412
Delmarva Power and Light Company [Member] | Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Revenue from Related Parties	2		2		3	4
Atlantic City Electric Company [Member] | Operating Segment [Member]
Segment Reporting Information [Line Items]
Revenues	309		319		658	629
Depreciation and Amortization	72		40		118	87
Operating Expenses	283		269		593	552
Interest expense, net	17		14		32	29
Income (Loss) before income taxes	11		36		38	50
Income taxes	0		(1)		1	(1)
Net income (loss)	11		37		37	51
Capital expenditures	92		116		179	239
Assets	5,052				5,052		4,556
Atlantic City Electric Company [Member] | Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Revenue from Related Parties	1		1		2	1
Corporate and Other [Member] | Corporate, Non-Segment [Member]
Segment Reporting Information [Line Items]
Revenues	384		524		961	1,013
Depreciation and Amortization	16		18		32	35
Operating Expenses	460		495		1,086	943
Interest expense, net	101		83		195	169
Income (Loss) before income taxes	(62)		(46)		(125)	(80)
Income taxes	(31)		(27)		114	(19)
Capital expenditures	38		15		60	61
Assets	6,345				6,345		7,626
Income (Loss) from Continuing Operations, Net of Tax, Including Portion Attributable to Noncontrolling Interest	(31)		(19)		(239)	(61)
Corporate and Other [Member] | Corporate, Non-Segment [Member] | Pepco Holdings LLC [Member]
Segment Reporting Information [Line Items]
Revenues	98		95		205	189
Depreciation and Amortization	7		7		15	14
Operating Expenses	99		97		197	192
Interest expense, net	1		2		5	6
Income (Loss) before income taxes	(2)		(1)		4	(6)
Income taxes	0		0		4	(3)
Net income (loss)	(2)		(1)		0	(2)
Capital expenditures	0		(1)		1	0
Assets	4,775				4,775		$ 4,933
Corporate and Other [Member] | Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Revenue from Related Parties	384		522		961	1,010
Corporate and Other [Member] | Intersegment Eliminations [Member] | Pepco Holdings LLC [Member]
Segment Reporting Information [Line Items]
Revenue from Related Parties	98		95		195	189
Rate-regulated electric revenues [Member]
Segment Reporting Information [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	3,934		3,739		8,415	7,609
Rate-regulated electric revenues [Member] | Pepco Holdings LLC [Member]
Segment Reporting Information [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	1,199		1,071		2,522	2,195
Rate-regulated electric revenues [Member] | Operating Segment [Member]
Segment Reporting Information [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	3,938		3,789		8,460	7,780
Rate-regulated electric revenues [Member] | Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	(6)		(9)		(14)	(16)
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	(3)		(3)		5	(7)
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	1,425		1,517		3,158	3,052
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	708		610		1,449	1,271
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	629		558		1,366	1,190
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	1,182		1,113		2,501	2,283
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	581		523		1,195	1,076
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	295		274		643	585
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	309		319		658	629
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		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		0	0
Rate-regulated natural gas revenues [Member]
Segment Reporting Information [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	307		234		1,124	867
Rate-regulated natural gas revenues [Member] | Pepco Holdings LLC [Member]
Segment Reporting Information [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	37		24		120	94
Rate-regulated natural gas revenues [Member] | Operating Segment [Member]
Segment Reporting Information [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	301		231		1,106	872
Rate-regulated natural gas revenues [Member] | Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	(1)		0		(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		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		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	108		83		414	311
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	157		124		574	466
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	37		24		120	95
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		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	37		24		120	95
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		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		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		0	0
Shared service and other revenues [Member] | Operating Segment [Member]
Segment Reporting Information [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	0		0		0	0
Shared service and other revenues [Member] | Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	(386)		(527)		(966)	(1,019)
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	(96)		(92)		(200)	(183)
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		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		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		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	2		3		5	6
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		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		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		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	384		524		961	1,013
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	$ 98		$ 95		$ 205	$ 189