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] 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] Common Stock [Member]	Baltimore Gas and Electric Company [Member] Nonredeemable Preferred Stock [Member]	Baltimore Gas and Electric Company [Member] Retained Earnings
Beginning Balance at Dec. 31, 2013	$ 22,732														$ 3,065	$ 2,415	$ 649	$ 1	$ 7,528	$ 1,588	$ 5,190	$ (1,639)	$ 2,389	$ 2,365	$ 1,360	$ 190	$ 1,005
Beginning Balance at Dec. 31, 2013	22,940		16,741	(2,327)	10,358	(2,040)	15	193																2,555
Beginning Balance at Dec. 31, 2013			892,034
Beginning Balance at Dec. 31, 2013									12,742		3,613	8,898	214	17
Net income	93				90			3	(185)		(185)			0	89		89		98			98		88			88
Net income on common stock	90														89									85
Long-term incentive plan activity			1,167
Employee stock purchase plan issuances			265
Appropriation of retained earnings for future dividends																						(98)	98
Long-term incentive plan activity	4		4
Employee stock purchase plan issuances	6		6
Common stock dividends	(268)				(268)										(80)		(80)		(76)				(76)
Contribution from parent									0			0		0					38		38
Distribution to members									(30)		(30)
Allocation of tax benefit from members									0			0
Preferred stock redemption premium															0		0
Allocation of tax benefit from parent																			2		2
Consolidated VIE dividend to non-controlling interest	2
Preferred security dividends	(3)							(3)							0		0							(3)		(3)
Noncontrolling interest acquired							(2)		2
Other comprehensive income (loss), net of tax	4	[1]							(21)	[1]			(21)
Sale of noncontrolling interest									2			0
ImpairmentOfLongLivedAssetsToBeDisposedOf									0					0
Deconsolidation of VIE									0			0		0
Ending Balance at Mar. 31, 2014	22,568														3,074	2,415	658	1	7,590	1,588	5,230	(1,639)	2,411	2,450	1,360	190	1,090
Ending Balance at Mar. 31, 2014	22,778		16,751	(2,327)	10,180	(2,036)	17	193																2,640
Ending Balance at Mar. 31, 2014			893,466
Ending Balance at Mar. 31, 2014									$ 12,508		$ 3,398	$ 8,898	$ 193	$ 19

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