Consolidated Statements of Operations and Comprehensive Income (Unaudited) (Parenthetical) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Prior service costs		$ 1	$ (4)
Actuarial loss reclassified to periodic cost, taxes		110	93
Transition obligation		2	2
Pension and non-pension postretirement benefit plan valuation adjustment, taxes		(237)	(171)
Change in unrealized gain (loss) on cash flow hedges, taxes		(68)	39
Change in unrealized gain (loss) on marketable securities, taxes		(1)	0
Change in unrealized gain (loss) on equity investments taxes		1	0
Actuarial loss reclassified to periodic cost, net of tax	(208)	(168)	(136)
Other Comprehensive Income (Loss), Amortization Adjustment from AOCI, Pension and Other Postretirement Benefit Plans, for Net Prior Service (Cost) Credit, Net of Tax	0	1	(5)
Other Comprehensive (Income) Loss, Reclassification Adjustment from AOCI, Pension and Other Postretirement Benefit Plans, for Net Transition (Asset) Obligation, Net of Tax	0	(2)	(4)
Exelon Generation Co L L C [Member]
Gain on disposal of discontinued operations, taxes	0	0	0
Change in unrealized gain (loss) on cash flow hedges, taxes	(262)	(262)	(64)
Change in unrealized gain (loss) on equity investments taxes		(1)
Commonwealth Edison Co [Member]
Change in unrealized gain (loss) on marketable securities, taxes	0	0	0
PECO Energy Co [Member]
Change in unrealized gain (loss) on marketable securities, taxes	0	0	0
Amortization of realized gain on settled cash flow swaps, taxes	$ 0	$ 0	$ 0