Basis of Presentation (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended			6 Months Ended
	Jun. 30, 2014	Mar. 31, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Depreciation and amortization	$ 590		$ 533	$ 1,154	$ 1,076
Operating and maintenance	2,166	1	1,892	4,024	3,656
Capital expenditures				2,501	2,518
Income Tax Expense (Benefit)	277		239	224	294
Interest Expense	228		246	445	863
Total interest expense to affiliates, net	10		6	20	13
Equity Method Investment Summarized Financial Information[Abstract]
Related Party Purchase Of Nuclear Output By Third Party Percentage				49.99%
Scenario Adjustment [Member]
Purchased power and fuel from affiliate				605
Exelon Generation Co L L C [Member]
Depreciation and amortization	254		210	466	424
Operating and maintenance	1,255		1,041	2,194	2,007
Capital expenditures				1,103	1,277
Income Tax Expense (Benefit)	199		149	(1)	148
Interest Expense	74		77	147	142
Purchased power and fuel from affiliate	69		290	417	611
Total interest expense to affiliates, net	(12)		(16)	(25)	(34)
Equity Method Investment Summarized Financial Information[Abstract]
Related Party Purchase Of Nuclear Output By Third Party Percentage				49.99%
Exelon Generation Co L L C [Member] | Scenario Adjustment [Member]
Purchased power and fuel from affiliate				611
Total interest expense to affiliates, net				34
Commonwealth Edison Co [Member]
Depreciation and amortization	174		170	347	337
Operating and maintenance	316		319	603	611
Capital expenditures				747	711
Income Tax Expense (Benefit)	72		66	137	8
Interest Expense	76		72	153	422
Total interest expense to affiliates, net	4		4	7	7
PECO Energy Co [Member]
Depreciation and amortization	59		56	117	113
Operating and maintenance	160		155	416	319
Capital expenditures				308	254
Income Tax Expense (Benefit)	23		32	57	87
Interest Expense	25		25	50	51
Total interest expense to affiliates, net	3		3	6	6
Baltimore Gas and Electric Company [Member]
Depreciation and amortization	89		82	197	175
Operating and maintenance	163		139	326	266
Capital expenditures				313	264
Income Tax Expense (Benefit)	14		16	72	70
Interest Expense	23		28	47	58
Purchased power and fuel from affiliate	85		99	205	212
Total interest expense to affiliates, net	(4)		(4)	(8)	(8)
Baltimore Gas and Electric Company [Member] | Scenario Adjustment [Member]
Total interest expense to affiliates, net				$ 8