Consolidated Statements of Operations and Comprehensive Income (Unaudited) (Parenthetical) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Prior service costs	$ (1)	$ 0
Actuarial loss reclassified to periodic cost, taxes	23	32
Pension and non-pension postretirement benefit plan valuation adjustment, taxes	(7)	49
Change in unrealized gain (loss) on cash flow hedges, taxes	18	33
Change in unrealized gain (loss) on equity investments taxes	(7)	(18)
Actuarial loss reclassified to periodic cost, net of tax	(34)	(51)
Other Comprehensive Income (Loss), Amortization Adjustment from AOCI, Pension and Other Postretirement Benefit Plans, for Net Prior Service (Cost) Credit, Net of Tax	1	0
Other Comprehensive (Income) Loss, Reclassification Adjustment from AOCI, Pension and Other Postretirement Benefit Plans, for Net Transition (Asset) Obligation, Net of Tax	0	0
Exelon Generation Co L L C [Member]
Change in unrealized gain (loss) on cash flow hedges, taxes	19	86
Change in unrealized gain (loss) on marketable securities, taxes	(2)
Change in unrealized gain (loss) on equity investments taxes	$ (7)	$ (18)