Consolidated Statement of Changes in Shareholders Equity (Unaudited) (USD $) In Millions, except Share data in Thousands	Total	Common Stock [Member]	Treasury Stock	Retained Earnings	Retained Earnings Cumulative Preferred Stock [Member]	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				612				6	188	155			33	173		173		209			209		106			106
Net income on common stock	612													173									100
Long-term incentive plan activity		1,408
Employee stock purchase plan issuances		499
Appropriation of retained earnings for future dividends																					(209)	209
Long-term incentive plan activity	32	32
Employee stock purchase plan issuances	14	14
Common stock dividends	(535)			(535)										(160)		(160)		(153)				(153)
Contribution from parent									0		0		0					112		112
Distribution to members									(235)	(235)
Allocation of tax benefit from members									(3)		(3)
Preferred stock redemption premium														0		0
Allocation of tax benefit from parent																		2		2
Consolidated VIE dividend to non-controlling interest	(415)						(415)		(415)				(415)
Preferred security dividends	6							0						0		0							(6)		(6)
Noncontrolling interest acquired	1,548						1,548		1,548				1,548
Reversal of CENG Equity Method AOCI	(116)					(116)			(116)			(116)
Other comprehensive income (loss), net of tax						250						(61)
Sale of noncontrolling interest									2		0		2
ImpairmentOfLongLivedAssetsToBeDisposedOf									0				0
Deconsolidation of VIE									0		0		0
Reduction of Equity for present value of contract payments	(131)	(131)
Ending Balance at Jun. 30, 2014	22,853													3,078	2,415	662	1	7,698	1,588	5,304	(1,639)	2,445	2,465	1,360	190	1,105
Ending Balance at Jun. 30, 2014	24,229	16,651	(2,327)	10,435		(1,906)	1,183	193															2,655
Ending Balance at Jun. 30, 2014		893,941
Ending Balance at Jun. 30, 2014									13,650	3,533	8,895	37	1,185
Beginning Balance at Mar. 31, 2014
Net income	557								372					84				111					19
Net income on common stock	522													84									16
Preferred stock redemption premium
Reversal of CENG Equity Method AOCI	(116)								(116)
Other comprehensive income (loss), net of tax	131								(155)
Reduction of Equity for present value of contract payments	(131)
Ending Balance at Jun. 30, 2014	22,853													3,078	2,415		1	7,698	1,588				2,465	1,360
Ending Balance at Jun. 30, 2014	24,229		(2,327)																				2,655
Ending Balance at Jun. 30, 2014									$ 13,650