Consolidated Statements of Operations and Comprehensive Income (Unaudited) - USD ($) shares in Millions, $ in Millions	3 Months Ended					6 Months Ended	9 Months Ended
	Sep. 30, 2017		Sep. 30, 2016		Mar. 23, 2016	Sep. 30, 2016	Sep. 30, 2017		Sep. 30, 2016
Operating revenues [Abstract]
Operating Revenue	$ 4,456		$ 4,535				$ 12,924		$ 12,243
Regulated Operating Revenue	4,313		4,467				12,225		11,243
Electric operating revenues	4,164	[1]	4,330	[1]			11,318	[2]	10,461	[2]
Natural gas operating revenues	149	[1]	137	[1]			906	[2]	781	[2]
Operating revenues from affiliates	0	[3]	1	[3]			2	[4]	3	[4]
Revenues	8,769		9,002				25,149		23,486
Operating expenses
Competitive businesses purchased power and fuel	2,316		2,584				7,268		6,599
Cost of Purchased Power	1,226		1,170				3,259		2,863
Operating and maintenance	2,300		2,338				7,732		7,677
Depreciation and amortization	1,002		1,195				2,814		2,821
Taxes other than income	456		449				1,313		1,168
Total operating expenses	7,300		7,736				22,386		21,128
Gain (Loss) on Disposition of Other Assets	(1)		1				4		41
Bargain purchase gain	7		0				233		0
Operating income	1,475		1,267				3,000		2,399
Other income and (deductions)
Interest expense, net	(377)		(506)				(1,165)		(1,148)
Interest expense to affiliates	(9)		(10)				(29)		(31)
Other, net	237		120				725		377
Total other income and (deductions)	(149)		(396)				(469)		(802)
Income before income taxes	1,326		871				2,531		1,597
Income taxes	452		340				595		625
Equity in losses of unconsolidated affiliates	(7)		(5)				(25)		(16)
Net income	867		526				1,911		956
Net income attributable to noncontrolling interests and preference stock dividends	43		36				12		26
Net income attributable to common shareholders	824		490				1,899		930
Other comprehensive income (loss), net of income taxes
Prior service benefit reclassified to periodic benefit cost	(14)		(12)				(42)		(35)
Actuarial loss reclassified to periodic benefit cost	49		47				147		140
Pension and non-pension postretirement benefit plan valuation adjustment	3		0				(55)		(3)
Unrealized gain (loss) on cash flow hedges	0		3				5		(4)
Other Comprehensive Income Unrealized Income Loss On Equity Investments Arising During Period Net Of Tax	1		(4)				5		(10)
Unrealized gain on foreign currency translation	4		2				7		8
Unrealized gain on marketable securities	1		0				2		0
Other comprehensive income	44		36				69		96
Comprehensive income	911		562				1,980		1,052
Comprehensive income attributable to noncontrolling interests and preference stock dividends	43		31				10		21
Comprehensive Income (Loss), Net of Tax, Attributable to Parent	$ 868		$ 531				$ 1,970		$ 1,031
Average shares of common stock outstanding:
Weighted average common shares outstanding — basic	962		925				941		924
Weighted average common shares outstanding — diluted	965		927				943		926
Earnings per average common share:
Basic	$ 0.86		$ 0.53				$ 2.02		$ 1.01
Diluted	0.85		0.53				2.01		1.00
Dividends declared per common share	$ 0.33		$ 0.32				$ 0.98		$ 0.95
Exelon Generation Co L L C [Member]
Operating revenues [Abstract]
Operating Revenue	$ 4,455		$ 4,533				$ 12,918		$ 12,234
Operating revenues from affiliates	296		502				894		1,129
Revenues	4,751		5,035				13,812		13,363
Operating expenses
Cost of Purchased Power	2,315		2,584				7,267		6,599
Purchased power from affiliate	16		5				19		10
Operating and maintenance	1,203		1,189				4,335		3,855
Operating and maintenance from affiliates	171		147				536		478
Depreciation and amortization	410		632				1,046		1,329
Taxes other than income	141		136				425		380
Total operating expenses	4,256		4,693				13,628		12,651
Gain (Loss) on Disposition of Other Assets	(2)		0				3		31
Bargain purchase gain	7		0				233		0
Operating income	500		342				420		743
Other income and (deductions)
Interest expense, net	(103)		(67)				(313)		(243)
Interest expense to affiliates	(10)		(10)				(29)		(30)
Other, net	209		185				648		395
Total other income and (deductions)	96		108				306		122
Income before income taxes	596		450				726		865
Income taxes	240		173				209		293
Equity in losses of unconsolidated affiliates	(8)		(6)				(26)		(16)
Net income	348		271				491		556
Net income attributable to noncontrolling interests	43		35				12		18
Net income attributable to membership interest	305		236				479		538
Other comprehensive income (loss), net of income taxes
Other Comprehensive Income (Loss), Unrealized Holding Gain (Loss) on Securities Arising During Period, Net of Tax	0		1				0		1
Unrealized gain (loss) on cash flow hedges	0		1				5		(3)
Other Comprehensive Income Unrealized Income Loss On Equity Investments Arising During Period Net Of Tax	0		0				4		(4)
Unrealized gain on foreign currency translation	4		2				7		8
Other comprehensive income	4		4				16		2
Comprehensive income	352		275				507		558
Comprehensive income attributable to noncontrolling interests and preference stock dividends	43		30				10		13
Comprehensive Income (Loss), Net of Tax, Attributable to Parent	309		245				497		545
Commonwealth Edison Co [Member]
Operating revenues [Abstract]
Electric operating revenues	1,568		1,493				4,215		4,019
Operating revenues from affiliates	3		4				12		12
Revenues	1,571		1,497				4,227		4,031
Operating expenses
Purchased power	489		435				1,178		1,104
Purchased power from affiliate	40		19				63		37
Operating and maintenance	277		327				897		950
Operating and maintenance from affiliates	69		50				199		163
Depreciation and amortization	212		196				631		574
Taxes other than income	80		82				223		222
Total operating expenses	1,167		1,109				3,191		3,050
Gain (Loss) on Disposition of Other Assets	0		1				0		6
Operating income	404		389				1,036		987
Other income and (deductions)
Interest expense, net	(86)		(194)				(265)		(364)
Interest expense to affiliates	(3)		(3)				(10)		(10)
Other, net	5		(80)				14		(72)
Total other income and (deductions)	(84)		(277)				(261)		(446)
Income before income taxes	320		112				775		541
Income taxes	131		75				328		244
Net income	189		37				447		297
Other comprehensive income (loss), net of income taxes
Comprehensive income	189		37				447		297
PECO Energy Co [Member]
Operating revenues [Abstract]
Electric operating revenues	660		738				1,798		1,966
Natural gas operating revenues	53		48				338		322
Operating revenues from affiliates	2		2				5		5
Revenues	715		788				2,141		2,293
Operating expenses
Purchased power	190		171				483		466
Purchased fuel	14		10				126		110
Purchased power from affiliate	31		91				110		233
Operating and maintenance	161		168				488		501
Operating and maintenance from affiliates	36		31				107		103
Depreciation and amortization	72		67				213		201
Taxes other than income	42		46				116		126
Total operating expenses	546		584				1,643		1,740
Operating income	169		204				498		553
Other income and (deductions)
Interest expense, net	(28)		(27)				(84)		(83)
Interest expense to affiliates	(3)		(3)				(9)		(9)
Other, net	2		2				6		6
Total other income and (deductions)	(29)		(28)				(87)		(86)
Income before income taxes	140		176				411		467
Income taxes	28		54				84		121
Net income	112		122				327		346
Other comprehensive income (loss), net of income taxes
Comprehensive income	112		122				327		346
Baltimore Gas and Electric Company [Member]
Operating revenues [Abstract]
Electric operating revenues	657		733				1,890		1,993
Natural gas operating revenues	78		72				461		412
Operating revenues from affiliates	3		7				12		16
Revenues	738		812				2,363		2,421
Operating expenses
Purchased power	159		164				407		399
Purchased fuel	13		14				118		109
Purchased power from affiliate	97		182				328		486
Operating and maintenance	138		150				421		494
Operating and maintenance from affiliates	37		28				111		94
Depreciation and amortization	109		101				348		307
Taxes other than income	61		58				180		172
Total operating expenses	614		697				1,913		2,061
Operating income	124		115				450		360
Other income and (deductions)
Interest expense, net	(24)		(24)				(69)		(64)
Interest expense to affiliates	(2)		(4)				(11)		(12)
Other, net	4		5				12		16
Total other income and (deductions)	(22)		(23)				(68)		(60)
Income before income taxes	102		92				382		300
Income taxes	40		36				151		109
Net income	62		56				231		191
Preference stock dividends	0		2				0		8
Net income attributable to common shareholders	62		54				231		183
Other comprehensive income (loss), net of income taxes
Comprehensive income	62		56				231		191
Comprehensive income attributable to noncontrolling interests and preference stock dividends	0		2				0		8
Comprehensive Income (Loss), Net of Tax, Attributable to Parent	62		54				231		183
Pepco Holdings LLC [Member] | Predecessor [Member]
Operating revenues [Abstract]
Electric operating revenues					$ 1,096
Natural gas operating revenues					57
Operating revenues from affiliates					0
Revenues					1,153
Operating expenses
Purchased power					471
Purchased fuel					26
Purchased power from affiliate					0
Operating and maintenance					294
Operating and maintenance from affiliates					0
Depreciation and amortization					152
Taxes other than income					105
Total operating expenses					1,048
Operating income					105
Other income and (deductions)
Interest expense, net					(65)
Other, net					(4)
Total other income and (deductions)					(69)
Income before income taxes					36
Income taxes					17
Net income					19
Other comprehensive income (loss), net of income taxes
Actuarial loss reclassified to periodic benefit cost					1
Other comprehensive income					1
Comprehensive income					$ 20
Pepco Holdings LLC [Member] | Successor [Member]
Operating revenues [Abstract]
Electric operating revenues	1,280		1,366			$ 2,485	3,417
Natural gas operating revenues	18		17			46	105
Operating revenues from affiliates	12		11			34	35
Revenues	1,310		1,394			2,565	3,557
Operating expenses
Purchased power	354		370			658	901
Purchased fuel	7		6			17	46
Purchased power from affiliate	112		207			362	371
Operating and maintenance	214		200			870	666
Operating and maintenance from affiliates	37		26			51	108
Depreciation and amortization	179		182			355	511
Taxes other than income	122		124			248	344
Total operating expenses	1,025		1,115			2,561	2,947
Gain (Loss) on Disposition of Other Assets	0						1
Operating income	285		279			4	611
Other income and (deductions)
Interest expense, net	(62)		(64)			(135)	(183)
Other, net	13		19			31	40
Total other income and (deductions)	(49)		(45)			(104)	(143)
Income before income taxes	236		234			(100)	468
Income taxes	83		68			(9)	109
Net income	153		166			(91)	359
Other comprehensive income (loss), net of income taxes
Actuarial loss reclassified to periodic benefit cost	0		0			0	0
Other comprehensive income	0		0			0	0
Comprehensive Income (Loss), Net of Tax, Attributable to Parent	153		166			$ (91)	359
Potomac Electric Power Company [Member]
Operating revenues [Abstract]
Electric operating revenues	603		634				1,645		1,692
Operating revenues from affiliates	1		1				4		3
Revenues	604		635				1,649		1,695
Operating expenses
Purchased power	111		84				268		340
Purchased power from affiliate	57		129				210		223
Operating and maintenance	89		100				296		488
Operating and maintenance from affiliates	14		9				40		20
Depreciation and amortization	82		76				242		221
Taxes other than income	102		105				282		287
Total operating expenses	455		503				1,338		1,579
Gain (Loss) on Disposition of Other Assets	0		0				1		8
Operating income	149		132				312		124
Other income and (deductions)
Interest expense, net	(31)		(30)				(89)		(98)
Other, net	7		12				22		28
Total other income and (deductions)	(24)		(18)				(67)		(70)
Income before income taxes	125		114				245		54
Income taxes	38		35				57		34
Net income	87		79				188		20
Other comprehensive income (loss), net of income taxes
Comprehensive income	87		79				188		20
Delmarva Power and Light Company [Member]
Operating revenues [Abstract]
Electric operating revenues	307		312				860		866
Natural gas operating revenues	18		17				105		102
Operating revenues from affiliates	2		2				6		6
Revenues	327		331				971		974
Operating expenses
Purchased power	75		81				215		297
Purchased fuel	7		6				46		41
Purchased power from affiliate	47		63				138		110
Operating and maintenance	71		50				204		327
Operating and maintenance from affiliates	8		5				23		11
Depreciation and amortization	45		44				124		120
Taxes other than income	15		14				43		42
Total operating expenses	268		263				793		948
Gain (Loss) on Disposition of Other Assets	0		4				0		4
Operating income	59		72				178		30
Other income and (deductions)
Interest expense, net	(13)		(12)				(38)		(37)
Other, net	4		3				10		9
Total other income and (deductions)	(9)		(9)				(28)		(28)
Income before income taxes	50		63				150		2
Income taxes	19		19				43		18
Net income	31		44				107		(16)
Other comprehensive income (loss), net of income taxes
Comprehensive Income (Loss), Net of Tax, Attributable to Parent	31		44				107		(16)
Atlantic City Electric Company [Member]
Operating revenues [Abstract]
Electric operating revenues	370		420				913		979
Operating revenues from affiliates	0		1				2		3
Revenues	370		421				915		982
Operating expenses
Purchased power	169		206				418		491
Purchased power from affiliate	7		15				24		29
Operating and maintenance	66		62				205		336
Operating and maintenance from affiliates	6		5				20		10
Depreciation and amortization	41		49				113		130
Taxes other than income	2		1				6		6
Total operating expenses	291		338				786		1,002
Gain (Loss) on Disposition of Other Assets	0		0				0		1
Operating income	79		83				129		(19)
Other income and (deductions)
Interest expense, net	(15)		(15)				(46)		(47)
Other, net	1		2				6		8
Total other income and (deductions)	(14)		(13)				(40)		(39)
Income before income taxes	65		70				89		(58)
Income taxes	24		23				12		(8)
Net income	41		47				77		(50)
Other comprehensive income (loss), net of income taxes
Comprehensive income							$ 77		$ (50)
Comprehensive Income (Loss), Net of Tax, Attributable to Parent	$ 41		$ 47

[1] Includes gross utility tax receipts from customers. The offsetting remittance of utility taxes to the governing bodies is recorded in expenses on the Registrants’ Consolidated Statements of Operations and Comprehensive Income. See Note 19 — Supplemental Financial Information for total utility taxes for the three months ended September 30, 2017 and 2016.

[2] Includes gross utility tax receipts from customers. The offsetting remittance of utility taxes to the governing bodies is recorded in expenses on the Registrants’ Consolidated Statements of Operations and Comprehensive Income. See Note 19 — Supplemental Financial Information for total utility taxes for the nine months ended September 30, 2017 and 2016.

[3] Intersegment revenues exclude sales to unconsolidated affiliates. The intersegment profit associated with Generation’s sale of certain products and services by and between Exelon’s segments is not eliminated in consolidation due to the recognition of intersegment profit in accordance with regulatory accounting guidance. For Exelon, these amounts are included in Operating revenues in the Consolidated Statements of Operations and Comprehensive Income.

[4] Intersegment revenues exclude sales to unconsolidated affiliates. The intersegment profit associated with Generation’s sale of certain products and services by and between Exelon’s segments is not eliminated in consolidation due to the recognition of intersegment profit in accordance with regulatory accounting guidance. For Exelon, these amounts are included in Operating revenues in the Consolidated Statements of Operations and Comprehensive Income.