Schedule I - Condensed Financial Information of Parent (Exelon Corporate) - Related Party Transactions - Summary of Related Party Transactions (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2014		Dec. 31, 2013		Dec. 31, 2012
Related Party Transaction [Line Items]
Total income (loss) in equity method investments	$ (20)		$ 10		$ (91)
Exelon Corporate [Member]
Related Party Transaction [Line Items]
Operating and maintenance from affiliates	38		34		72
Interest income from affiliates, net	53		36		75
Total income (loss) in equity method investments	1,779		1,903		1,278
Cash contributions received from affiliates	1,370		1,175		2,074
Accounts receivable from affiliates	24		22
Receivables from affiliates	818		179
Investments in affiliates	26,670		26,390
Total receivable from affiliates (noncurrent)	943		1,522
Total payables to affiliates (noncurrent)	182		176
Exelon Corporate [Member] | Business Services Company [Member]
Related Party Transaction [Line Items]
Operating and maintenance from affiliates	38	[1]	34	[1]	72	[1]
Accounts receivable from affiliates	2	[1]	3	[1]
Receivables from affiliates	262	[1]	179	[1]
Investments in affiliates	193	[1]	201	[1]
Exelon Corporate [Member] | Exelon Energy Delivery Company LLC [Member]
Related Party Transaction [Line Items]
Total income (loss) in equity method investments	958	[2]	834	[2]	713	[2]
Investments in affiliates	13,590	[2]	12,956	[2]
Exelon Corporate [Member] | Exelon Ventures Company LLC [Member]
Related Party Transaction [Line Items]
Total income (loss) in equity method investments	926	[3]	1,076	[3]	564	[3]
Investments in affiliates	0	[3]	12,750	[3]
Exelon Corporate [Member] | UII LLC [Member]
Related Party Transaction [Line Items]
Total income (loss) in equity method investments	(6)		(2)		25
Investments in affiliates	130		470
Exelon Corporate [Member] | Exelon Transmission Company LLC [Member]
Related Party Transaction [Line Items]
Total income (loss) in equity method investments	(7)		(5)		(3)
Investments in affiliates	1		3
Exelon Corporate [Member] | ExelonEnterprise [Member]
Related Party Transaction [Line Items]
Total income (loss) in equity method investments	(1)		0		0
Investments in affiliates	23		0
Exelon Corporate [Member] | Exelon Generation Consolidated [Member]
Related Party Transaction [Line Items]
Total income (loss) in equity method investments	(91)		0		0
Receivables from affiliates	556		0
Investments in affiliates	12,720		0
Exelon Corporate [Member] | Exelon Consolidations [Member]
Related Party Transaction [Line Items]
Total income (loss) in equity method investments	0	[4]	0	[4]	(21)	[4]
Investments in affiliates	4		0
Exelon Corporate [Member] | Exelon Generation Co L L C [Member]
Related Party Transaction [Line Items]
Accounts receivable from affiliates	12		7
Total receivable from affiliates (noncurrent)	943		1,522
Exelon Corporate [Member] | Commonwealth Edison Co [Member]
Related Party Transaction [Line Items]
Accounts receivable from affiliates	3		9
Total payables to affiliates (noncurrent)	182		176
Exelon Corporate [Member] | PECO Energy Co [Member]
Related Party Transaction [Line Items]
Accounts receivable from affiliates	2		2
Exelon Corporate [Member] | Baltimore Gas and Electric Company [Member]
Related Party Transaction [Line Items]
Accounts receivable from affiliates	5		1
Exelon Corporate [Member] | VEBA [Member]
Related Party Transaction [Line Items]
Investments in affiliates	$ 9		$ 10

[1] Exelon Corporate receives a variety of corporate support services from BSC, including legal, human resources, financial, information technology and supply management services. All services are provided at cost, including applicable overhead.

[2] Exelon Energy Delivery Company, LLC consists of ComEd, PECO and BGE.

[3] Exelon Ventures Company, LLC primarily consisted of Generation

[4] Equity in earnings of investments for Exelon Consolidations represents the intercompany income component that offsets the corresponding intercompany expense at Generation for upgrades in transmission assets owned by ComEd, which are reflected as assets at Exelon Corporate.