Consolidated Statement of Changes in Shareholders Equity (Unaudited) (USD $) In Millions, except Share data in Thousands	Total	Common Stock [Member]	Treasury Stock	Retained Earnings	Accumulated Other Comprehensive (Loss) Income, Net		Noncontrolling Interest	Preference Stock Not Subject To Mandatory Redemption [Member]	Exelon Generation Co L L C [Member]	Exelon Generation Co L L C [Member] Undistributed Earnings [Member]	Exelon Generation Co L L C [Member] Membership Interest [Member]	Exelon Generation Co L L C [Member] Accumulated Other Comprehensive (Loss) Income, Net		Exelon Generation Co L L C [Member] Noncontrolling Interest	PECO Energy Co [Member]	PECO Energy Co [Member] Common Stock [Member]	PECO Energy Co [Member] Retained Earnings	PECO Energy Co [Member] Accumulated Other Comprehensive (Loss) Income, Net	Commonwealth Edison Co [Member]	Commonwealth Edison Co [Member] Common Stock [Member]	Commonwealth Edison Co [Member] Retained Earnings	Commonwealth Edison Co [Member] Accumulated Other Comprehensive (Loss) Income, Net	Commonwealth Edison Co [Member] Other Paid-In Capital	Commonwealth Edison Co [Member] Retained Deficit Unappropriated	Commonwealth Edison Co [Member] Retained Earnings Appropriated	Baltimore Gas and Electric Company [Member]	Baltimore Gas and Electric Company [Member] Undistributed Earnings [Member]	Baltimore Gas and Electric Company [Member] Common Stock [Member]	Baltimore Gas and Electric Company [Member] Membership Interest [Member]	Baltimore Gas and Electric Company [Member] Retained Earnings	Baltimore Gas and Electric Company [Member] Preference Stock Not Subject To Mandatory Redemption [Member]
Beginning Balance at Dec. 31, 2009
Noncontrolling interest in income of consolidated entity							$ (3)
Ending Balance at Dec. 31, 2010															2,883	2,361	522	0	6,910	1,588		(1)	4,992	(1,639)	1,970		779	1,294	2,073
Ending Balance at Dec. 31, 2010	13,563	9,006	(2,327)	9,304	(2,423)																					2,263					190
Beginning Balance at Dec. 31, 2010		696,589
Beginning Balance at Dec. 31, 2010									7,177	2,633	3,526	1,013		5
Net income	2,499			2,495				4	1,771	1,771					389		389		416		416					136	136		136
Net income on common stock	2,495														385											123
Long-term incentive plan activity		861
Employee stock purchase plan issuances		662
Appropriation of retained earnings for future dividends																			0					(416)	416
Long-term incentive plan activity	76	76
Employee stock purchase plan issuances	25	25
Common stock dividends	(1,744)			(1,744)											(348)		(348)		(300)						(300)	85				85
Distribution to members									(172)	(172)
Allocation of tax benefit from members									30		30
Transfer of AmerGen pension and non-pension postretirement benefit plans to Exelon, net of income taxes									0
Allocation of tax benefit from parent															18	18			11				11
Preferred security dividends	4							4							(4)		(4)									13	13		13
Repayment of receivable from parent															0
Acquisition of Exelon Wind														0
Other comprehensive income (loss), net of tax	(27)				(27)				(98)			(98)			0			0	0
Ending Balance at Dec. 31, 2011															2,938	2,379	559	0	7,037	1,588			5,003	(1,639)	2,086		817		2,111
Ending Balance at Dec. 31, 2011	14,388	9,107	(2,327)	10,055	(2,450)																					2,301
Ending Balance at Dec. 31, 2011		698,112
Ending Balance at Dec. 31, 2011									8,708	4,232	3,556	915		5
Net income	200								168						96				87							(33)
Ending Balance at Mar. 31, 2012
Beginning Balance at Dec. 31, 2011															2,938	2,379	559	0	7,037	1,588		(1)	5,003	(1,639)	2,086		817	1,294	2,111
Beginning Balance at Dec. 31, 2011	14,388	9,107	(2,327)	10,055	(2,450)		3																			2,301					190
Beginning Balance at Dec. 31, 2011		698,112
Beginning Balance at Dec. 31, 2011									8,708	4,232	3,556	915		5
Net income	1,171			1,160			(3)	14	558	562				(4)	381		381		379		379					4	4		4
Net income on common stock	1,160														377											(9)
Long-term incentive plan activity		2,432
Employee stock purchase plan issuances		857
Appropriation of retained earnings for future dividends																			0					(379)	379
Long-term incentive plan activity	126	126
Employee stock purchase plan issuances	26	26
Common stock dividends	(1,322)			(1,322)											(343)		(343)		(105)						(105)	0	0		0
Common stock issuance - Constellation merger - Shares	188,124
Common stock issuance - Constellation merger - Value	7,365	7,365							5,264		5,264
Contribution from parent																										66		66
Distribution to members									(1,626)	(1,626)
Allocation of tax benefit from members									48		48
Allocation of tax benefit from parent															9	9			11				11
BGE preference stock acquired	193																														193
Preferred security dividends	14							14							(4)		(4)									(13)	(13)		(13)
Repayment of receivable from parent															0
Acquisition of Exelon Wind									115		8			107
Noncontrolling interest acquired	114	8					106
Other comprehensive income (loss), net of tax	(317)				(317)				(402)			(402)			1			1	1			1
Ending Balance at Dec. 31, 2012	21,431														2,982	2,388	593	1	7,323	1,588		0	5,014	(1,639)	2,360	2,168	808	1,360	2,168
Ending Balance at Dec. 31, 2012	21,730	16,632	(2,327)	9,893	(2,767)		106																			2,358					190
Ending Balance at Dec. 31, 2012		889,525
Ending Balance at Dec. 31, 2012								193	12,665	3,168	8,876	513		108
Beginning Balance at Sep. 30, 2012
Net income	378								137						79				160							15
Ending Balance at Dec. 31, 2012	21,431														2,982				7,323	1,588						2,168
Ending Balance at Dec. 31, 2012	21,730		(2,327)																							2,358
Ending Balance at Dec. 31, 2012									12,665
Net income	(4)								(18)						121				(81)							77
Ending Balance at Mar. 31, 2013
Beginning Balance at Dec. 31, 2012	21,431														2,982	2,388	593	1	7,323	1,588			5,014	(1,639)	2,360	2,168	808		2,168
Beginning Balance at Dec. 31, 2012	21,730	16,632	(2,327)	9,893	(2,767)		106																			2,358
Beginning Balance at Dec. 31, 2012		889,525
Beginning Balance at Dec. 31, 2012								193	12,665	3,168	8,876	513		108
Net income	1,729			1,719			(10)	20	1,060	1,070					395		395		249		249					210	210		210
Net income on common stock	1,719														388											197
Long-term incentive plan activity		1,445
Employee stock purchase plan issuances	1,064
Appropriation of retained earnings for future dividends																			0					(249)	249
Long-term incentive plan activity	81	81
Employee stock purchase plan issuances	28	28
Common stock dividends	(1,254)			(1,254)											(332)		(332)		(220)						(220)
Distribution to members									(625)	(625)
Allocation of tax benefit from members									26		26
Preferred stock redemption premium	(6)							(6)							6		6
Allocation of tax benefit from parent															27	27			176				176
Consolidated VIE dividend to non-controlling interest	(63)								63					63
Preferred security dividends	14							14							(1)		(1)									(13)	(13)		(13)
Repayment of receivable from parent															0
Noncontrolling interest acquired	(63)						(63)
Other comprehensive income (loss), net of tax	727				727	[1]			(299)			(299)	[1]		0			0	0
Noncontrolling interest in income of consolidated entity														10
Sale of noncontrolling interest									(3)		(3)
ImpairmentOfLongLivedAssetsToBeDisposedOf									0					0
Deconsolidation of VIE	(18)						(18)		(19)		(1)			(18)
Ending Balance at Dec. 31, 2013	22,732														3,065	2,415	649	1	7,528	1,588		0	5,190	(1,639)	2,389	2,365	1,005	1,360	2,365
Ending Balance at Dec. 31, 2013	22,940	16,741	(2,327)	10,358	(2,040)		15																			2,555					190
Ending Balance at Dec. 31, 2013		892,034
Ending Balance at Dec. 31, 2013								193	12,742	3,613	8,898	214		17
Beginning Balance at Sep. 30, 2013
Net income	495								269						102				109							47
Ending Balance at Dec. 31, 2013	22,732														3,065				7,528	1,588		0				2,365		1,360
Ending Balance at Dec. 31, 2013	22,940		(2,327)																							2,555					190
Ending Balance at Dec. 31, 2013									$ 12,742

[1] All amounts are net of tax. Amounts in parenthesis represent a decrease in accumulated other comprehensive income.