Retirement Benefits (Tables)

3 Months Ended

Mar. 31, 2013

Retirement Benefits [Line Items]

Schedule of Defined Benefit Plans Disclosures [Text Block]

						Other
						Postretirement
		Pension Benefits				Benefits
		Three Months Ended				Three Months Ended
		March 31,				March 31,
		2013		2012		2013		2012
Service cost		$	80	$	61	$	41	$	37
Interest cost			163		164		48		51
Expected return on assets			(253)		(232)		(33)		(29)
Amortization of:
	Transition obligation		0		0		0		3
	Prior service cost (benefit)		3		4		(4)		(3)
	Actuarial loss		140		106		20		19
Net periodic benefit cost		$	133	$	103	$	72	$	78

Schedule Of Pension And Other Postretirement Benefit Costs [Text Block]

	Three Months Ended March 31,
Pension and Other Postretirement Benefit Costs		2013		2012
Generation	$	87	$	81
ComEd		77		69
PECO		11		13
BGE (a)		13		16
BSC (b)		17		14

BGE's pension and postretirement benefit costs for the threemonths ended March 31, 2012include $12 million of costs incurred prior to the closing of Exelon's merger with Constellation on March 12, 2012.These amounts are not included in Exelon's net periodic benefit costs for the three months ended March 31, 2012 shown in the first table of the Defined Benefit Pension and Other Postretirement Benefits section above.

(b)       These amounts primarily represent amounts billed to Exelon's subsidiaries through intercompany allocations. These amounts are not included in the Generation, ComEd, PECO or BGE amounts above.

Schedule Of Defined Contributions [Text Block]

	Three Months Ended March 31,
Savings Plan Matching Contributions	2013		2012
Exelon	$	22	$	16
Generation		11		8
ComEd		5		4
PECO		2		2
BGE (a)		2		2
BSC (b)		2		1

• BGE's matching contributions for the three months ended March 31, 2012 include $1million of costs incurred prior to the closing of Exelon's merger with Constellation on March 12, 2012, which is not included in Exelon's matching contributions for the three months ended March 31, 2012.
• These amounts primarily represent amounts billed to Exelon's subsidiaries through intercompany allocations. These costs are not included in the Generation, ComEd, PECO or BGE amounts above.