Consolidated Statements of Operations and Comprehensive Income (Unaudited) - USD ($) shares in Millions, $ in Millions		3 Months Ended
		Mar. 31, 2020	Mar. 31, 2019
Operating revenues
Revenues from alternative revenue programs		$ 67	$ (5)
Operating revenues from affiliates		1	0
Total operating revenues		8,747	9,477
Operating expenses
Operating and maintenance		2,204	2,189
Depreciation and amortization		1,021	1,075
Taxes other than income taxes		437	445
Total operating expenses		7,529	8,262
Gain on sales of assets and businesses		2	3
Operating income		1,220	1,218
Other income and (deductions)
Interest expense, net		(404)	(397)
Interest expense to affiliates		(6)	(6)
Other, net		(725)	467
Total other income and (deductions)		(1,135)	64
Income before income taxes		85	1,282
Income taxes		(294)	310
Equity in losses of unconsolidated affiliates		(3)	(6)
Net income (loss)		376	966
Net income attributable to noncontrolling interests		(206)	59
Net income (loss) attributable to common shareholders		582	907
Other comprehensive income (loss), net of income taxes
Prior service benefit reclassified to periodic benefit cost		(10)	(16)
Actuarial loss reclassified to periodic benefit cost		47	36
Pension and non-pension postretirement benefit plan valuation adjustment		(7)	(38)
Unrealized (loss) gain on cash flow hedges		(1)	0
Unrealized (loss) gain on investments in unconsolidated affiliates		0	(2)
Unrealized gain (loss) on foreign currency translation		(8)	2
Other comprehensive income		21	(18)
Comprehensive income		397	948
Comprehensive (loss) income attributable to noncontrolling interests		(206)	58
Comprehensive income attributable to common shareholders/membership interest		$ 603	$ 890
Average shares of common stock outstanding:
Basic average shares of common stock outstanding		975	971
Assumed exercise and/or distributions of stock-based awards		1	1
Diluted average shares of common stock outstanding	[1]	976	972
Earnings per average common share:
Basic earnings per average common share		$ 0.60	$ 0.93
Diluted earnings per average common share		$ 0.60	$ 0.93
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount		0	0
Exelon Generation Co L L C [Member]
Operating revenues
Operating revenues from affiliates		$ 330	$ 317
Total operating revenues		4,733	5,296
Operating expenses
Purchased power and/or fuel from affiliates		(6)	1
Operating and maintenance		1,121	1,068
Operating and maintenance from affiliates		142	150
Depreciation and amortization		304	405
Taxes other than income taxes		129	135
Total operating expenses		4,400	4,963
Operating income		333	333
Other income and (deductions)
Interest expense, net		(100)	(102)
Interest expense to affiliates		(9)	(9)
Other, net		(771)	430
Total other income and (deductions)		(880)	319
Income before income taxes		(547)	652
Income taxes		(389)	224
Equity in losses of unconsolidated affiliates		(3)	(6)
Net income (loss)		(161)	422
Net income attributable to noncontrolling interests		(206)	59
Net income attributable to membership interest		45	363
Other comprehensive income (loss), net of income taxes
Unrealized (loss) gain on cash flow hedges		(1)	1
Unrealized (loss) gain on investments in unconsolidated affiliates		0	(2)
Unrealized gain (loss) on foreign currency translation		(8)	2
Other comprehensive income		(9)	1
Comprehensive income		(170)	423
Comprehensive (loss) income attributable to noncontrolling interests		(206)	58
Comprehensive income attributable to common shareholders/membership interest		36	365
Commonwealth Edison Co [Member]
Operating revenues
Revenues from alternative revenue programs		12	(28)
Operating revenues from affiliates		5	4
Total operating revenues		1,439	1,408
Operating expenses
Purchased power and/or fuel from affiliates		97	97
Operating and maintenance		243	259
Operating and maintenance from affiliates		74	62
Depreciation and amortization		273	251
Taxes other than income taxes		75	78
Total operating expenses		1,151	1,135
Gain on sales of assets and businesses		0	3
Operating income		288	276
Other income and (deductions)
Interest expense, net		(91)	(84)
Interest expense to affiliates		(3)	(3)
Other, net		10	8
Total other income and (deductions)		(84)	(79)
Income before income taxes		204	197
Income taxes		36	40
Net income (loss)		168	157
Other comprehensive income (loss), net of income taxes
Comprehensive income		168	157
PECO Energy Co [Member]
Operating revenues
Revenues from alternative revenue programs		2	(3)
Operating revenues from affiliates		2	1
Total operating revenues		813	900
Operating expenses
Purchased power and/or fuel from affiliates		36	44
Operating and maintenance		179	187
Operating and maintenance from affiliates		38	38
Depreciation and amortization		86	81
Taxes other than income taxes		39	41
Total operating expenses		625	678
Operating income		188	222
Other income and (deductions)
Interest expense, net		(33)	(30)
Interest expense to affiliates		(3)	(3)
Other, net		3	4
Total other income and (deductions)		(33)	(29)
Income before income taxes		155	193
Income taxes		15	25
Net income (loss)		140	168
Other comprehensive income (loss), net of income taxes
Comprehensive income		140	168
Baltimore Gas and Electric Company [Member]
Operating revenues
Revenues from alternative revenue programs		36	10
Operating revenues from affiliates			6
Total operating revenues		937	976
Operating expenses
Purchased power and/or fuel from affiliates		98	75
Operating and maintenance		146	153
Operating and maintenance from affiliates		42	39
Depreciation and amortization		143	136
Taxes other than income taxes		69	68
Total operating expenses		688	756
Operating income		249	220
Other income and (deductions)
Interest expense, net		(32)	(29)
Other, net		5	5
Total other income and (deductions)		(27)	(24)
Income before income taxes		222	196
Income taxes		41	36
Net income (loss)		181	160
Other comprehensive income (loss), net of income taxes
Comprehensive income		181	160
Pepco Holdings LLC [Member]
Operating revenues
Revenues from alternative revenue programs		18	15
Operating revenues from affiliates		3	3
Total operating revenues		1,171	1,228
Operating expenses
Purchased power and/or fuel from affiliates		104	101
Operating and maintenance		219	239
Operating and maintenance from affiliates		38	33
Depreciation and amortization		194	180
Taxes other than income taxes		114	111
Total operating expenses		1,000	1,053
Gain on sales of assets and businesses		2	0
Operating income		173	175
Other income and (deductions)
Interest expense, net		(67)	(65)
Other, net		13	12
Total other income and (deductions)		(54)	(53)
Income before income taxes		119	122
Income taxes		11	5
Net income (loss)		108	117
Other comprehensive income (loss), net of income taxes
Comprehensive income attributable to common shareholders/membership interest		108	117
Potomac Electric Power Company [Member]
Operating revenues
Revenues from alternative revenue programs		15	14
Operating revenues from affiliates		1	2
Total operating revenues		544	575
Operating expenses
Purchased power and/or fuel from affiliates		79	70
Operating and maintenance		60	64
Operating and maintenance from affiliates		51	54
Depreciation and amortization		95	94
Taxes other than income taxes		92	92
Total operating expenses		462	491
Operating income		82	84
Other income and (deductions)
Interest expense, net		(34)	(34)
Other, net		9	7
Total other income and (deductions)		(25)	(27)
Income before income taxes		57	57
Income taxes		5	2
Net income (loss)		52	55
Other comprehensive income (loss), net of income taxes
Comprehensive income attributable to common shareholders/membership interest		52	55
Delmarva Power and Light Company [Member]
Operating revenues
Revenues from alternative revenue programs		1	0
Operating revenues from affiliates		2	2
Total operating revenues		350	380
Operating expenses
Purchased power and/or fuel from affiliates		22	23
Operating and maintenance		42	45
Operating and maintenance from affiliates		37	39
Depreciation and amortization		48	46
Taxes other than income taxes		16	14
Total operating expenses		284	308
Operating income		66	72
Other income and (deductions)
Interest expense, net		(16)	(15)
Other, net		2	3
Total other income and (deductions)		(14)	(12)
Income before income taxes		52	60
Income taxes		7	7
Net income (loss)		45	53
Other comprehensive income (loss), net of income taxes
Comprehensive income		45	53
Atlantic City Electric Company [Member]
Operating revenues
Revenues from alternative revenue programs		1	1
Operating revenues from affiliates		1	1
Total operating revenues		276	273
Operating expenses
Purchased power and/or fuel from affiliates		2	8
Operating and maintenance		45	47
Operating and maintenance from affiliates		33	34
Depreciation and amortization		43	31
Taxes other than income taxes		2	1
Total operating expenses		251	252
Gain on sales of assets and businesses		2	0
Operating income		27	21
Other income and (deductions)
Interest expense, net		(14)	(14)
Interest expense to affiliates		(1)	0
Other, net		2	3
Total other income and (deductions)		(13)	(11)
Income before income taxes		14	10
Income taxes		1	0
Net income (loss)		13	10
Other comprehensive income (loss), net of income taxes
Comprehensive income		13	10
Generation commodities and services
Operating revenues
Revenue from Contract with Customer, Including Assessed Tax		4,403	4,979
Operating expenses
Purchased power and/or fuel		2,710	3,204
Generation commodities and services | Exelon Generation Co L L C [Member]
Operating revenues
Revenue from Contract with Customer, Including Assessed Tax		4,403	4,979
Operating expenses
Purchased power and/or fuel		2,710	3,204
Rate-regulated utility revenues
Operating revenues
Revenue from Contract with Customer, Including Assessed Tax		4,276	4,503
Operating expenses
Purchased power and/or fuel		1,157	1,349
Electricity, US Regulated | Commonwealth Edison Co [Member]
Operating revenues
Revenue from Contract with Customer, Including Assessed Tax		1,422	1,432
Operating expenses
Purchased power and/or fuel		389	388
Electricity, US Regulated | PECO Energy Co [Member]
Operating revenues
Revenue from Contract with Customer, Including Assessed Tax		600	622
Operating expenses
Purchased power and/or fuel		164	152
Electricity, US Regulated | Baltimore Gas and Electric Company [Member]
Operating revenues
Revenue from Contract with Customer, Including Assessed Tax		595	652
Operating expenses
Purchased power and/or fuel		114	190
Electricity, US Regulated | Pepco Holdings LLC [Member]
Operating revenues
Revenue from Contract with Customer, Including Assessed Tax		1,086	1,139
Operating expenses
Purchased power and/or fuel		300	355
Electricity, US Regulated | Potomac Electric Power Company [Member]
Operating revenues
Revenue from Contract with Customer, Including Assessed Tax		528	559
Operating expenses
Purchased power and/or fuel		85	117
Electricity, US Regulated | Delmarva Power and Light Company [Member]
Operating revenues
Revenue from Contract with Customer, Including Assessed Tax		283	307
Operating expenses
Purchased power and/or fuel		88	107
Electricity, US Regulated | Atlantic City Electric Company [Member]
Operating revenues
Revenue from Contract with Customer, Including Assessed Tax		274	271
Operating expenses
Purchased power and/or fuel		126	131
Natural Gas, US Regulated | PECO Energy Co [Member]
Operating revenues
Revenue from Contract with Customer, Including Assessed Tax		209	280
Operating expenses
Purchased power and/or fuel		83	135
Natural Gas, US Regulated | Baltimore Gas and Electric Company [Member]
Operating revenues
Revenue from Contract with Customer, Including Assessed Tax		300	308
Operating expenses
Purchased power and/or fuel		76	95
Natural Gas, US Regulated | Pepco Holdings LLC [Member]
Operating revenues
Revenue from Contract with Customer, Including Assessed Tax		64	71
Operating expenses
Purchased power and/or fuel		31	34
Natural Gas, US Regulated | Delmarva Power and Light Company [Member]
Operating revenues
Revenue from Contract with Customer, Including Assessed Tax		64	71
Operating expenses
Purchased power and/or fuel		$ 31	$ 34

[1] The number of stock options not included in the calculation of diluted common shares outstanding due to their antidilutive effect was immaterial for the three months ended March 31, 2020 and March 31, 2019.