Consolidated Statements of Operations and Comprehensive Income (Unaudited) - USD ($) shares in Millions, $ in Millions		3 Months Ended		6 Months Ended
		Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Operating revenues
Revenues from alternative revenue programs		$ 47	$ (122)	$ 176	$ (55)
Operating revenues from affiliates		0	1	0	2
Total operating revenues		7,915	7,322	17,805	16,069
Operating expenses
Operating and maintenance		2,447	2,433	4,426	4,637
Depreciation and amortization		1,666	1,001	3,363	2,023
Taxes other than income taxes		432	411	870	847
Total operating expenses		7,561	6,769	17,643	14,298
Gain on sales of assets and businesses		12	12	83	13
Operating income (loss)		366	565	245	1,784
Other income and (deductions)
Interest expense, net		(390)	(421)	(770)	(824)
Interest expense to affiliates		(6)	(6)	(13)	(13)
Other, net		581	656	806	(68)
Total other income and (deductions)		185	229	23	(905)
Income before income taxes		551	794	268	879
Income taxes		74	219	55	(75)
Equity in losses of unconsolidated affiliates		(1)	(1)	(2)	(4)
Net income (loss)		476	574	211	950
Net income (loss) attributable to noncontrolling interests		75	53	99	(153)
Net Income (Loss) Available to Common Stockholders, Basic		401	521	112	1,103
Other comprehensive income (loss), net of income taxes
Prior service benefit reclassified to periodic benefit cost		(1)	(10)	(2)	(20)
Actuarial loss reclassified to periodic benefit cost		56	47	112	94
Pension and non-pension postretirement benefit plan valuation adjustment		0	2	(2)	(5)
Unrealized (loss) gain on cash flow hedges		0	0	0	(1)
Unrealized gain (loss) on foreign currency translation		2	2	3	(6)
Other comprehensive income		57	41	111	62
Comprehensive income		533	615	322	1,012
Comprehensive income (loss) attributable to noncontrolling interests		75	53	99	(153)
Comprehensive income attributable to common shareholders/membership interest		$ 458	$ 562	$ 223	$ 1,165
Average shares of common stock outstanding:
Basic average shares of common stock outstanding		978	976	978	975
Assumed exercise and/or distributions of stock-based awards		1	0	1	1
Diluted average shares of common stock outstanding	[1]	979	976	979	976
Earnings per average common share
Basic earnings per average common share		$ 0.41	$ 0.53	$ 0.11	$ 1.13
Diluted earnings per average common share		$ 0.41	$ 0.53	$ 0.11	$ 1.13
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount		0	1	0	0
Exelon Generation Co L L C [Member]
Operating revenues
Operating revenues from affiliates		$ 254	$ 271	$ 549	$ 601
Total operating revenues		4,153	3,880	9,712	8,613
Operating expenses
Purchased power and fuel from affiliates		(5)	(3)	(5)	(9)
Operating and maintenance		1,337	1,053	2,194	2,174
Operating and maintenance from affiliates		137	136	282	277
Depreciation and amortization		930	300	1,869	604
Taxes other than income taxes		118	116	239	246
Total operating expenses		4,469	3,547	11,141	7,947
Gain on sales of assets and businesses		8	12	79	12
Operating income (loss)		(308)	345	(1,350)	678
Other income and (deductions)
Interest expense, net		(72)	(78)	(140)	(179)
Interest expense to affiliates		(4)	(9)	(8)	(18)
Other, net		508	602	675	(168)
Total other income and (deductions)		432	515	527	(365)
Income before income taxes		124	860	(823)	313
Income taxes		110	329	(70)	(59)
Equity in losses of unconsolidated affiliates		(1)	(2)	(3)	(4)
Net income (loss)		13	529	(756)	368
Net income (loss) attributable to noncontrolling interests		74	53	98	(153)
Net income attributable to membership interest		(61)	476	(854)	521
Other comprehensive income (loss), net of income taxes
Unrealized (loss) gain on cash flow hedges		0	0	0	(1)
Unrealized gain (loss) on foreign currency translation		2	2	3	(6)
Other comprehensive income		2	2	3	(7)
Comprehensive income		15	531	(753)	361
Comprehensive income (loss) attributable to noncontrolling interests		74	53	98	(153)
Comprehensive income attributable to common shareholders/membership interest		(59)	478	(851)	514
Commonwealth Edison Co [Member]
Operating revenues
Revenues from alternative revenue programs		9	(25)	64	(13)
Operating revenues from affiliates		5	11	11	16
Total operating revenues		1,517	1,417	3,052	2,856
Operating expenses
Purchased power and/or fuel from affiliates		79	84	163	181
Operating and maintenance		250	469	495	713
Operating and maintenance from affiliates		73	67	144	140
Depreciation and amortization		296	274	589	547
Taxes other than income taxes		77	71	153	146
Total operating expenses		1,196	1,345	2,406	2,497
Operating income (loss)		321	72	646	359
Other income and (deductions)
Interest expense, net		(95)	(95)	(187)	(186)
Interest expense to affiliates		(3)	(3)	(6)	(6)
Other, net		15	11	22	22
Total other income and (deductions)		(83)	(87)	(171)	(170)
Income before income taxes		238	(15)	475	189
Income taxes		46	46	85	82
Net income (loss)		192	(61)	390	107
Other comprehensive income (loss), net of income taxes
Comprehensive income		192	(61)	390	107
PECO Energy Co [Member]
Operating revenues
Revenues from alternative revenue programs		7	4	17	5
Operating revenues from affiliates		2	2	4	4
Total operating revenues		693	681	1,582	1,493
Operating expenses
Purchased power and/or fuel from affiliates		40	40	81	76
Operating and maintenance		166	235	360	414
Operating and maintenance from affiliates		43	40	83	78
Depreciation and amortization		87	88	173	173
Taxes other than income taxes		49	39	92	78
Total operating expenses		552	618	1,231	1,242
Operating income (loss)		141	63	351	251
Other income and (deductions)
Interest expense, net		(39)	(33)	(74)	(65)
Interest expense to affiliates		(3)	(3)	(6)	(6)
Other, net		7	5	12	7
Total other income and (deductions)		(35)	(31)	(68)	(64)
Income before income taxes		106	32	283	187
Income taxes		2	(7)	12	9
Net income (loss)		104	39	271	178
Other comprehensive income (loss), net of income taxes
Comprehensive income		104	39	271	178
Baltimore Gas and Electric Company [Member]
Operating revenues
Revenues from alternative revenue programs		(10)	(37)	8	0
Operating revenues from affiliates		7	4	13	10
Total operating revenues		682	616	1,656	1,554
Operating expenses
Purchased power and/or fuel from affiliates		59	69	129	167
Operating and maintenance		147	146	299	293
Operating and maintenance from affiliates		46	41	91	83
Depreciation and amortization		141	129	293	272
Taxes other than income taxes		67	63	139	132
Total operating expenses		620	573	1,372	1,263
Operating income (loss)		62	43	284	291
Other income and (deductions)
Interest expense, net		(34)	(32)	(67)	(64)
Other, net		9	6	16	10
Total other income and (deductions)		(25)	(26)	(51)	(54)
Income before income taxes		37	17	233	237
Income taxes		(8)	(22)	(21)	18
Net income (loss)		45	39	254	219
Other comprehensive income (loss), net of income taxes
Comprehensive income		45	39	254	219
Pepco Holdings LLC [Member]
Operating revenues
Revenues from alternative revenue programs		41	(64)	88	(47)
Operating revenues from affiliates		4	3	7	7
Total operating revenues		1,140	1,016	2,384	2,187
Operating expenses
Purchased power and/or fuel from affiliates		79	78	177	182
Operating and maintenance		217	245	434	464
Operating and maintenance from affiliates		39	36	79	74
Depreciation and amortization		194	191	404	385
Taxes other than income taxes		109	109	222	222
Total operating expenses		955	956	2,013	1,955
Gain on sales of assets and businesses		0	0	0	2
Operating income (loss)		185	60	371	234
Other income and (deductions)
Interest expense, net		(67)	(67)	(134)	(134)
Other, net		20	14	36	26
Total other income and (deductions)		(47)	(53)	(98)	(108)
Income before income taxes		138	7	273	126
Income taxes		(3)	(87)	5	(76)
Equity in losses of unconsolidated affiliates		0	0	1	0
Net income (loss)		141	94	269	202
Other comprehensive income (loss), net of income taxes
Comprehensive income attributable to common shareholders/membership interest		141	94	269	202
Potomac Electric Power Company [Member]
Operating revenues
Revenues from alternative revenue programs		19	(13)	46	2
Operating revenues from affiliates		1	1	3	3
Total operating revenues		523	494	1,076	1,039
Operating expenses
Purchased power and/or fuel from affiliates		57	60	130	139
Operating and maintenance		62	67	118	128
Operating and maintenance from affiliates		51	52	103	103
Depreciation and amortization		96	92	199	186
Taxes other than income taxes		87	87	177	179
Total operating expenses		429	436	895	899
Operating income (loss)		94	58	181	140
Other income and (deductions)
Interest expense, net		(35)	(34)	(69)	(68)
Other, net		13	9	25	18
Total other income and (deductions)		(22)	(25)	(44)	(50)
Income before income taxes		72	33	137	90
Income taxes		(3)	(24)	3	(19)
Net income (loss)		75	57	134	109
Other comprehensive income (loss), net of income taxes
Comprehensive income		75	57	134	109
Delmarva Power and Light Company [Member]
Operating revenues
Revenues from alternative revenue programs		10	(25)	19	(24)
Operating revenues from affiliates		2	2	4	4
Total operating revenues		298	267	680	617
Operating expenses
Purchased power and/or fuel from affiliates		17	16	37	38
Operating and maintenance		41	54	85	97
Operating and maintenance from affiliates		39	38	79	75
Depreciation and amortization		51	47	104	94
Taxes other than income taxes		16	17	33	32
Total operating expenses		255	263	564	547
Operating income (loss)		43	4	116	70
Other income and (deductions)
Interest expense, net		(16)	(15)	(30)	(31)
Other, net		4	2	6	5
Total other income and (deductions)		(12)	(13)	(24)	(26)
Income before income taxes		31	(9)	92	44
Income taxes		1	(28)	6	(20)
Net income (loss)		30	19	86	64
Other comprehensive income (loss), net of income taxes
Comprehensive income		30	19	86	64
Atlantic City Electric Company [Member]
Operating revenues
Revenues from alternative revenue programs		12	(26)	23	(25)
Operating revenues from affiliates		1	1	1	1
Total operating revenues		319	256	629	532
Operating expenses
Purchased power and/or fuel from affiliates		5	2	9	5
Operating and maintenance		39	48	82	94
Operating and maintenance from affiliates		34	34	68	66
Depreciation and amortization		40	44	87	86
Taxes other than income taxes		2	2	4	4
Total operating expenses		269	258	552	509
Gain on sales of assets and businesses		0	0	0	2
Operating income (loss)		50	(2)	77	25
Other income and (deductions)
Interest expense, net		(14)	(15)	(29)	(29)
Other, net		0	2	2	3
Total other income and (deductions)		(14)	(13)	(27)	(26)
Income before income taxes		36	(15)	50	(1)
Income taxes		(1)	(33)	(1)	(32)
Net income (loss)		37	18	51	31
Other comprehensive income (loss), net of income taxes
Comprehensive income		37	18	51	31
Generation commodities and services
Operating revenues
Revenue from Contract with Customer, Including Assessed Tax		3,900	3,612	9,165	8,016
Operating expenses
Purchased power and/or fuel		1,952	1,945	6,562	4,655
Generation commodities and services | Exelon Generation Co L L C [Member]
Operating revenues
Revenue from Contract with Customer, Including Assessed Tax		3,899	3,609	9,163	8,012
Operating expenses
Purchased power and/or fuel		1,952	1,945	6,562	4,655
Rate-regulated utility revenues
Operating revenues
Revenue from Contract with Customer, Including Assessed Tax		3,968	3,832	8,464	8,108
Operating expenses
Purchased power and/or fuel		1,064	979	2,422	2,136
Electricity, US Regulated
Operating revenues
Revenue from Contract with Customer, Including Assessed Tax		3,787	3,475	7,775	7,222
Electricity, US Regulated | Commonwealth Edison Co [Member]
Operating revenues
Revenue from Contract with Customer, Including Assessed Tax		1,503	1,431	2,977	2,853
Operating expenses
Purchased power and/or fuel		421	380	862	770
Electricity, US Regulated | PECO Energy Co [Member]
Operating revenues
Revenue from Contract with Customer, Including Assessed Tax		602	580	1,251	1,180
Operating expenses
Purchased power and/or fuel		145	142	334	306
Electricity, US Regulated | Baltimore Gas and Electric Company [Member]
Operating revenues
Revenue from Contract with Customer, Including Assessed Tax		560	530	1,180	1,125
Operating expenses
Purchased power and/or fuel		133	107	295	221
Electricity, US Regulated | Pepco Holdings LLC [Member]
Operating revenues
Revenue from Contract with Customer, Including Assessed Tax		1,071	1,047	2,195	2,133
Operating expenses
Purchased power and/or fuel		308	286	656	586
Electricity, US Regulated | Potomac Electric Power Company [Member]
Operating revenues
Revenue from Contract with Customer, Including Assessed Tax		503	506	1,027	1,034
Operating expenses
Purchased power and/or fuel		76	78	168	164
Electricity, US Regulated | Delmarva Power and Light Company [Member]
Operating revenues
Revenue from Contract with Customer, Including Assessed Tax		262	260	562	543
Operating expenses
Purchased power and/or fuel		82	80	185	169
Electricity, US Regulated | Atlantic City Electric Company [Member]
Operating revenues
Revenue from Contract with Customer, Including Assessed Tax		306	281	605	556
Operating expenses
Purchased power and/or fuel		149	128	302	254
Natural Gas, US Regulated
Operating revenues
Revenue from Contract with Customer, Including Assessed Tax		228	236	865	832
Natural Gas, US Regulated | PECO Energy Co [Member]
Operating revenues
Revenue from Contract with Customer, Including Assessed Tax		82	95	310	304
Operating expenses
Purchased power and/or fuel		22	34	108	117
Natural Gas, US Regulated | Baltimore Gas and Electric Company [Member]
Operating revenues
Revenue from Contract with Customer, Including Assessed Tax		125	119	455	419
Operating expenses
Purchased power and/or fuel		27	18	126	95
Natural Gas, US Regulated | Pepco Holdings LLC [Member]
Operating revenues
Revenue from Contract with Customer, Including Assessed Tax		24	30	94	94
Operating expenses
Purchased power and/or fuel		9	11	41	42
Natural Gas, US Regulated | Delmarva Power and Light Company [Member]
Operating revenues
Revenue from Contract with Customer, Including Assessed Tax		24	30	95	94
Operating expenses
Purchased power and/or fuel		$ 9	$ 11	$ 41	$ 42

[1] The number of stock options not included in the calculation of diluted common shares outstanding due to their antidilutive effect was zero for the three and six months ended June 30, 2021 and 1 million and less than 1 million for the three and six months ended June 30, 2020, respectively.