Consolidated Statements of Operations and Comprehensive Income (Unaudited) (USD $) In Millions, except Per Share data, unless otherwise specified	3 Months Ended
	Mar. 31, 2015		Mar. 31, 2014
Operating revenues [Abstract]
Operating revenues from affiliates	$ 1	[1]	$ 1	[1]
Interest expense	8,830	[2]	7,237	[2]
Operating expenses
Purchased power and fuel	4,470		4,006
Purchased power and fuel from affiliates	0		334
Operating and maintenance	2,081		1,858
Depreciation and amortization	610		564
Taxes other than income	304		293
Total operating expenses	7,465		7,055
Equity in losses of unconsolidated affiliates			(19)
Gain (Loss) on Sale of Assets and Asset Impairment Charges	1		5
Operating income	1,366		168
Other income and (deductions)
Interest expense, net	(335)		(217)
Interest expense to affiliates	(10)		(10)
Other, net	80		98
Total other income and (deductions)	(265)		(129)
Income before income taxes	1,101		39
Income taxes	363		(54)
Net income	738		93
Net income attributable to noncontrolling interest and preference stock dividends	45		3
Net income attributable to common shareholders	693		90
Pension and non-pension postretirement benefit plans:
Prior service (benefit) cost reclassified to periodic benefit cost	(11)		1
Actuarial loss reclassified to periodic cost	54		34
Pension and non-pension postretirement benefit plans valuation adjustment	26		13
Unrealized gain (loss) on cash flow hedges	6		(25)
Unrealized gain on equity investments	0		12
Unrealized loss on foreign currency translation	(12)		(5)
Other comprehensive income	11	[3]	4	[3]
Comprehensive income	749		97
Average shares of common stock outstanding:
Average common shares outstanding — basic	862		858
Average common shares outstanding — diluted	867		861
Earnings per average common share:
Earnings per share - basic (in usd per share)	$ 0.80		$ 0.10
Earnings per average common share - diluted
Earnings per share - diluted (in usd per share)	$ 0.80		$ 0.10
Dividends per common share (in usd per share)	$ 0.31		$ 0.31
Exelon Generation Co L L C [Member]
Operating revenues [Abstract]
Operating revenues	5,629		4,056
Operating revenues from affiliates	211		334
Interest expense	5,840		4,390
Operating expenses
Purchased power and fuel from affiliates	7		349
Purchased power and fuel	3,426		3,008
Operating and maintenance	1,162		938
Operating and maintenance from affiliates	149		149
Depreciation and amortization	254		211
Taxes other than income	122		105
Total operating expenses	5,120		4,760
Equity in losses of unconsolidated affiliates			(19)
Gain (Loss) on Sale of Assets and Asset Impairment Charges	(1)		5
Operating income	719		(384)
Other income and (deductions)
Interest expense, net	(90)		(73)
Interest expense to affiliates	(12)		(12)
Other, net	94		85
Total other income and (deductions)	(8)		0
Income before income taxes	711		(384)
Income taxes	226		(199)
Net income	485		(185)
Net income attributable to noncontrolling interests	42		0
Net income (loss) attributable to membership interest	443		(185)
Pension and non-pension postretirement benefit plans:
Unrealized gain (loss) on cash flow hedges	(5)		(25)
Unrealized gain on equity investments	0		12
Unrealized loss on foreign currency translation	(12)		(5)
Unrealized loss on marketable securities	0		(3)
Other comprehensive income	(17)	[3]	(21)	[3]
Comprehensive income	468		(206)
Commonwealth Edison Co [Member]
Operating revenues [Abstract]
Operating revenues	1,184		1,133
Operating revenues from affiliates	1		1
Interest expense	1,185		1,134
Operating expenses
Purchased power and fuel	318		212
Purchased power and fuel from affiliates	9		108
Operating and maintenance	333		287
Operating and maintenance from affiliates	45		39
Depreciation and amortization	175		173
Taxes other than income	75		77
Total operating expenses	955		896
Operating income	230		238
Other income and (deductions)
Interest expense, net	(81)		(77)
Interest expense to affiliates	(3)		(3)
Other, net	3		5
Total other income and (deductions)	(81)		(75)
Income before income taxes	149		163
Income taxes	59		65
Net income	90		98
Pension and non-pension postretirement benefit plans:
Comprehensive income	90		98
PECO Energy Co [Member]
Operating revenues [Abstract]
Operating revenues	985		992
Operating revenues from affiliates	0		1
Interest expense	985		993
Operating expenses
Purchased power and fuel	376		377
Purchased power and fuel from affiliates	62		87
Operating and maintenance	197		256
Operating and maintenance from affiliates	25		24
Depreciation and amortization	62		58
Taxes other than income	41		42
Total operating expenses	763		844
Equity in losses of unconsolidated affiliates			0
Gain (Loss) on Sale of Assets and Asset Impairment Charges			0
Gain (Loss) on Disposition of Assets	1
Operating income	223		149
Other income and (deductions)
Interest expense, net	(25)		(25)
Interest expense to affiliates	(3)		(3)
Other, net	2		2
Total other income and (deductions)	(26)		(26)
Income before income taxes	197		123
Income taxes	58		34
Net income	139		89
Net income attributable to common shareholders	139		89
Pension and non-pension postretirement benefit plans:
Comprehensive income	139		89
Baltimore Gas and Electric Company [Member]
Operating revenues [Abstract]
Operating revenues	1,029		1,038
Operating revenues from affiliates	7		16
Interest expense	1,036		1,054
Operating expenses
Purchased power and fuel	350		409
Purchased power and fuel from affiliates	137		120
Operating and maintenance	156		163
Operating and maintenance from affiliates	26		25
Depreciation and amortization	106		108
Taxes other than income	57		60
Total operating expenses	832		885
Equity in losses of unconsolidated affiliates			0
Operating income	204		169
Other income and (deductions)
Interest expense, net	(21)		(23)
Interest expense to affiliates	(4)		(4)
Other, net	4		4
Total other income and (deductions)	(21)		(23)
Income before income taxes	183		146
Income taxes	74		58
Net income	109		88
Preferred security dividends and redemption	3		3
Net income attributable to common shareholders	106		85
Pension and non-pension postretirement benefit plans:
Comprehensive income	$ 109		$ 88

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[2] {F|ahBzfndlYmZpbGluZ3MtaHJkcmoLEgZYTUxEb2MiXlhCUkxEb2NHZW5JbmZvOmVmN2Y3ZjVlMDU4YzQwMGVhOTA4ZWJkNWMzOGFmYjNhfFRleHRTZWxlY3Rpb246M0JGQzRCODYwOEI3OTJGM0VFMzEwOTNBRjYwNTk1MjUM}

[3] All amounts are net of tax. Amounts in parentheses represent a decrease in accumulated other comprehensive income.