Consolidated Statements of Operations and Comprehensive Income (Unaudited) - USD ($) shares in Millions, $ in Millions		3 Months Ended
		Mar. 31, 2021	Mar. 31, 2020
Operating revenues
Revenues from alternative revenue programs		$ 129	$ 67
Operating revenues from affiliates		0	1
Total operating revenues		9,890	8,747
Operating expenses
Operating and maintenance		1,979	2,204
Depreciation and amortization		1,697	1,021
Taxes other than income taxes		438	437
Total operating expenses		10,082	7,529
Gain on sales of assets and businesses		71	2
Operating income (loss)		(121)	1,220
Other income and (deductions)
Interest expense, net		(380)	(404)
Interest expense to affiliates		(6)	(6)
Other, net		225	(725)
Total other income and (deductions)		(161)	(1,135)
Income before income taxes		(282)	85
Income taxes		(19)	(294)
Equity in losses of unconsolidated affiliates		(1)	(3)
Net income (loss)		(264)	376
Net income (loss) attributable to noncontrolling interests		25	(206)
Net Income (Loss) Available to Common Stockholders, Basic		(289)	582
Other comprehensive income (loss), net of income taxes
Prior service benefit reclassified to periodic benefit cost		(1)	(10)
Actuarial loss reclassified to periodic benefit cost		56	47
Pension and non-pension postretirement benefit plan valuation adjustment		(2)	(7)
Unrealized (loss) gain on cash flow hedges		0	(1)
Unrealized gain (loss) on foreign currency translation		1	(8)
Other comprehensive income		54	21
Comprehensive income		(210)	397
Comprehensive income (loss) attributable to noncontrolling interests		25	(206)
Comprehensive income attributable to common shareholders/membership interest		$ (235)	$ 603
Average shares of common stock outstanding:
Basic average shares of common stock outstanding		977	975
Assumed exercise and/or distributions of stock-based awards		0	1
Diluted average shares of common stock outstanding	[1]	977	976
(Losses) earnings per average common share
Basic earnings per average common share		$ (0.30)	$ 0.60
Diluted earnings per average common share		$ (0.30)	$ 0.60
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount		0	0
Retained Earnings [Member]
Other income and (deductions)
Net income (loss)		$ (289)	$ 582
Exelon Generation Co L L C [Member]
Operating revenues
Operating revenues from affiliates		295	330
Total operating revenues		5,559	4,733
Operating expenses
Purchased power and/or fuel from affiliates		0	(6)
Operating and maintenance		856	1,121
Operating and maintenance from affiliates		145	142
Depreciation and amortization		940	304
Taxes other than income taxes		121	129
Total operating expenses		6,672	4,400
Gain on sales of assets and businesses		71	0
Operating income (loss)		(1,042)	333
Other income and (deductions)
Interest expense, net		(68)	(100)
Interest expense to affiliates		(4)	(9)
Other, net		167	(771)
Total other income and (deductions)		95	(880)
Income before income taxes		(947)	(547)
Income taxes		(179)	(389)
Equity in losses of unconsolidated affiliates		(1)	(3)
Net income (loss)		(769)	(161)
Net income (loss) attributable to noncontrolling interests		24	(206)
Net income attributable to membership interest		(793)	45
Other comprehensive income (loss), net of income taxes
Unrealized (loss) gain on cash flow hedges		0	(1)
Unrealized gain (loss) on foreign currency translation		1	(8)
Other comprehensive income		1	(9)
Comprehensive income		(768)	(170)
Comprehensive income (loss) attributable to noncontrolling interests		24	(206)
Comprehensive income attributable to common shareholders/membership interest		(792)	36
Commonwealth Edison Co [Member]
Operating revenues
Revenues from alternative revenue programs		54	12
Operating revenues from affiliates		6	5
Total operating revenues		1,535	1,439
Operating expenses
Purchased power and/or fuel from affiliates		85	97
Operating and maintenance		245	243
Operating and maintenance from affiliates		71	74
Depreciation and amortization		292	273
Taxes other than income taxes		75	75
Total operating expenses		1,210	1,151
Operating income (loss)		325	288
Other income and (deductions)
Interest expense, net		(93)	(91)
Interest expense to affiliates		(3)	(3)
Other, net		7	10
Total other income and (deductions)		(89)	(84)
Income before income taxes		236	204
Income taxes		39	36
Net income (loss)		197	168
Other comprehensive income (loss), net of income taxes
Comprehensive income		197	168
PECO Energy Co [Member]
Operating revenues
Revenues from alternative revenue programs		10	2
Operating revenues from affiliates		2	2
Total operating revenues		889	813
Operating expenses
Purchased power and/or fuel from affiliates		41	36
Operating and maintenance		193	179
Operating and maintenance from affiliates		41	38
Depreciation and amortization		86	86
Taxes other than income taxes		43	39
Total operating expenses		679	625
Operating income (loss)		210	188
Other income and (deductions)
Interest expense, net		(35)	(33)
Interest expense to affiliates		(3)	(3)
Other, net		5	3
Total other income and (deductions)		(33)	(33)
Income before income taxes		177	155
Income taxes		10	15
Net income (loss)		167	140
Other comprehensive income (loss), net of income taxes
Comprehensive income		167	140
PECO Energy Co [Member] | Retained Earnings [Member]
Other income and (deductions)
Net income (loss)		167	140
Baltimore Gas and Electric Company [Member]
Operating revenues
Revenues from alternative revenue programs		18	36
Operating revenues from affiliates		6	6
Total operating revenues		974	937
Operating expenses
Purchased power and/or fuel from affiliates		70	98
Operating and maintenance		152	146
Operating and maintenance from affiliates		45	42
Depreciation and amortization		152	143
Taxes other than income taxes		72	69
Total operating expenses		752	688
Operating income (loss)		222	249
Other income and (deductions)
Interest expense, net		(34)	(32)
Other, net		8	5
Total other income and (deductions)		(26)	(27)
Income before income taxes		196	222
Income taxes		(13)	41
Net income (loss)		209	181
Other comprehensive income (loss), net of income taxes
Comprehensive income		209	181
Baltimore Gas and Electric Company [Member] | Retained Earnings [Member]
Other income and (deductions)
Net income (loss)		209	181
Pepco Holdings LLC [Member]
Operating revenues
Revenues from alternative revenue programs		46	18
Operating revenues from affiliates		3	3
Total operating revenues		1,244	1,171
Operating expenses
Purchased power and/or fuel from affiliates		98	104
Operating and maintenance		216	219
Operating and maintenance from affiliates		40	38
Depreciation and amortization		210	194
Taxes other than income taxes		113	114
Total operating expenses		1,058	1,000
Gain on sales of assets and businesses		0	2
Operating income (loss)		186	173
Other income and (deductions)
Interest expense, net		(67)	(67)
Other, net		17	13
Total other income and (deductions)		(50)	(54)
Income before income taxes		136	119
Income taxes		8	11
Net income (loss)		128	108
Other comprehensive income (loss), net of income taxes
Comprehensive income attributable to common shareholders/membership interest		128	108
Potomac Electric Power Company [Member]
Operating revenues
Revenues from alternative revenue programs		26	15
Operating revenues from affiliates		1	1
Total operating revenues		553	544
Operating expenses
Purchased power and/or fuel from affiliates		74	79
Operating and maintenance		56	60
Operating and maintenance from affiliates		52	51
Depreciation and amortization		102	95
Taxes other than income taxes		90	92
Total operating expenses		466	462
Operating income (loss)		87	82
Other income and (deductions)
Interest expense, net		(34)	(34)
Other, net		12	9
Total other income and (deductions)		(22)	(25)
Income before income taxes		65	57
Income taxes		6	5
Net income (loss)		59	52
Other comprehensive income (loss), net of income taxes
Comprehensive income		59	52
Potomac Electric Power Company [Member] | Retained Earnings [Member]
Other income and (deductions)
Net income (loss)		59	52
Delmarva Power and Light Company [Member]
Operating revenues
Revenues from alternative revenue programs		9	1
Operating revenues from affiliates		2	2
Total operating revenues		382	350
Operating expenses
Purchased power and/or fuel from affiliates		20	22
Operating and maintenance		44	42
Operating and maintenance from affiliates		39	37
Depreciation and amortization		53	48
Taxes other than income taxes		17	16
Total operating expenses		309	284
Operating income (loss)		73	66
Other income and (deductions)
Interest expense, net		(15)	(16)
Other, net		3	2
Total other income and (deductions)		(12)	(14)
Income before income taxes		61	52
Income taxes		5	7
Net income (loss)		56	45
Other comprehensive income (loss), net of income taxes
Comprehensive income		56	45
Delmarva Power and Light Company [Member] | Retained Earnings [Member]
Other income and (deductions)
Net income (loss)		56	45
Atlantic City Electric Company [Member]
Operating revenues
Revenues from alternative revenue programs		11	1
Operating revenues from affiliates		1	1
Total operating revenues		310	276
Operating expenses
Purchased power and/or fuel from affiliates		4	2
Operating and maintenance		42	45
Operating and maintenance from affiliates		34	33
Depreciation and amortization		47	43
Taxes other than income taxes		2	2
Total operating expenses		282	251
Gain on sales of assets and businesses		0	2
Operating income (loss)		28	27
Other income and (deductions)
Interest expense, net		(15)	(14)
Interest expense to affiliates		0	(1)
Other, net		1	2
Total other income and (deductions)		(14)	(13)
Income before income taxes		14	14
Income taxes		0	1
Net income (loss)		14	13
Other comprehensive income (loss), net of income taxes
Comprehensive income		14	13
Atlantic City Electric Company [Member] | Retained Earnings [Member]
Other income and (deductions)
Net income (loss)		14	13
Generation commodities and services
Operating revenues
Revenue from Contract with Customer, Including Assessed Tax		5,265	4,404
Operating expenses
Purchased power and/or fuel		4,610	2,710
Generation commodities and services | Exelon Generation Co L L C [Member]
Operating revenues
Revenue from Contract with Customer, Including Assessed Tax		5,264	4,403
Operating expenses
Purchased power and/or fuel		4,610	2,710
Rate-regulated utility revenues
Operating revenues
Revenue from Contract with Customer, Including Assessed Tax		4,496	4,276
Operating expenses
Purchased power and/or fuel		1,358	1,157
Electricity, US Regulated
Operating revenues
Revenue from Contract with Customer, Including Assessed Tax		3,988	3,748
Electricity, US Regulated | Commonwealth Edison Co [Member]
Operating revenues
Revenue from Contract with Customer, Including Assessed Tax		1,475	1,422
Operating expenses
Purchased power and/or fuel		442	389
Electricity, US Regulated | PECO Energy Co [Member]
Operating revenues
Revenue from Contract with Customer, Including Assessed Tax		649	600
Operating expenses
Purchased power and/or fuel		189	164
Electricity, US Regulated | Baltimore Gas and Electric Company [Member]
Operating revenues
Revenue from Contract with Customer, Including Assessed Tax		620	595
Operating expenses
Purchased power and/or fuel		162	114
Electricity, US Regulated | Pepco Holdings LLC [Member]
Operating revenues
Revenue from Contract with Customer, Including Assessed Tax		1,124	1,086
Operating expenses
Purchased power and/or fuel		348	300
Electricity, US Regulated | Potomac Electric Power Company [Member]
Operating revenues
Revenue from Contract with Customer, Including Assessed Tax		526	528
Operating expenses
Purchased power and/or fuel		92	85
Electricity, US Regulated | Delmarva Power and Light Company [Member]
Operating revenues
Revenue from Contract with Customer, Including Assessed Tax		300	283
Operating expenses
Purchased power and/or fuel		103	88
Electricity, US Regulated | Atlantic City Electric Company [Member]
Operating revenues
Revenue from Contract with Customer, Including Assessed Tax		298	274
Operating expenses
Purchased power and/or fuel		153	126
Natural Gas, US Regulated
Operating revenues
Revenue from Contract with Customer, Including Assessed Tax		637	595
Natural Gas, US Regulated | PECO Energy Co [Member]
Operating revenues
Revenue from Contract with Customer, Including Assessed Tax		228	209
Operating expenses
Purchased power and/or fuel		86	83
Natural Gas, US Regulated | Baltimore Gas and Electric Company [Member]
Operating revenues
Revenue from Contract with Customer, Including Assessed Tax		330	300
Operating expenses
Purchased power and/or fuel		99	76
Natural Gas, US Regulated | Pepco Holdings LLC [Member]
Operating revenues
Revenue from Contract with Customer, Including Assessed Tax		71	64
Operating expenses
Purchased power and/or fuel		33	31
Natural Gas, US Regulated | Delmarva Power and Light Company [Member]
Operating revenues
Revenue from Contract with Customer, Including Assessed Tax		71	64
Operating expenses
Purchased power and/or fuel		$ 33	$ 31

[1] The number of stock options not included in the calculation of diluted common shares outstanding due to their antidilutive effect was less than 1 million for the three months ended March 31, 2021 and March 31, 2020.