Segment Information (Details) (USD $)	3 Months Ended										12 Months Ended
	Dec. 31, 2013		Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012		Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2013		Dec. 31, 2012		Dec. 31, 2011
Segment Reporting Information [Line Items]
Revenues	$ 6,163,000,000		$ 6,502,000,000	$ 6,141,000,000	$ 6,082,000,000	$ 6,254,000,000		$ 6,579,000,000	$ 5,966,000,000	$ 4,690,000,000	$ 24,888,000,000		$ 23,489,000,000		$ 19,063,000,000
Operating revenues from affiliates													48,000,000		9,000,000
Income (loss) from continuing operations before income taxes											2,773,000,000		1,798,000,000		3,956,000,000
Depreciation and amortization											2,153,000,000		1,881,000,000		1,347,000,000
Operating Expenses											21,242,000,000		21,018,000,000		14,583,000,000
Interest Revenue (Expense), Net											1,356,000,000		928,000,000		726,000,000
Income taxes											1,044,000,000		627,000,000		1,457,000,000
Net income (loss)	495,000,000		738,000,000	490,000,000	(4,000,000)	378,000,000		296,000,000	286,000,000	200,000,000	1,729,000,000		1,171,000,000		2,499,000,000
Equity in earnings (losses) of unconsolidated affiliates											10,000,000		(91,000,000)		(1,000,000)
Capital expenditures											5,395,000,000		5,789,000,000		4,042,000,000
Total assets	79,924,000,000					78,561,000,000					79,924,000,000		78,561,000,000
Segment Reporting Additional Information [Abstract]
Number of reportable segments											9,000,000
Utility taxes											449,000,000	[1]	463,000,000	[1]	443,000,000	[1]
Unrealized Gain (Loss) on Derivatives											445,000,000		604,000,000		(291,000,000)
Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Operating revenues from affiliates											14,000,000		6,000,000		9,000,000
Net income (loss)											(14,000,000)				(9,000,000)
PECO Energy Co Affiliate [Member]
Segment Reporting Information [Line Items]
Operating revenues from affiliates											10,000,000	[2]	6,000,000	[2]	9,000,000	[2]
Exelon Generation Co L L C [Member]
Segment Reporting Additional Information [Abstract]
Number of reportable segments											6,000,000
Utility taxes											79,000,000		82,000,000		27,000,000
Exelon Generation Co L L C [Member] | Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Operating revenues from affiliates													1,660,000,000		1,161,000,000
Exelon Generation Co L L C [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Revenues											15,630,000,000		14,437,000,000		10,447,000,000
Operating revenues from affiliates											1,367,000,000
Income (loss) from continuing operations before income taxes											1,675,000,000	[3]	1,058,000,000	[3]	2,827,000,000	[3]
Depreciation and amortization											856,000,000		768,000,000		570,000,000
Operating Expenses											13,976,000,000		13,226,000,000		7,571,000,000
Interest Revenue (Expense), Net											357,000,000	[3]	301,000,000	[3]	170,000,000	[3]
Income taxes											615,000,000	[3]	500,000,000	[3]	1,056,000,000	[3]
Net income (loss)											1,060,000,000	[3]	558,000,000	[3]	1,771,000,000	[3]
Equity in earnings (losses) of unconsolidated affiliates											10,000,000		(91,000,000)		(1,000,000)
Capital expenditures											2,752,000,000		3,554,000,000		2,491,000,000
Total assets	41,232,000,000	[3]				40,681,000,000	[3]				41,232,000,000	[3]	40,681,000,000	[3]
Generation Mid Atlantic [Member]
Segment Reporting Information [Line Items]
Revenues											5,204,000,000		5,038,000,000		4,052,000,000
Revenue net of purchased power and fuel expense from external customers											3,273,290,670.04		3,477,000,000		3,350,000,000
Revenue net of purchased power and fuel expense from transactions with other operating segments of the same entity											(3,290,670.04)		(44,000,000)
Revenue net of purchased power and fuel expense, Total											3,270,000,000		3,433,000,000		3,350,000,000
Generation Mid Atlantic [Member] | Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Operating revenues from affiliates											22,000,000		(44,000,000)
Generation Mid Atlantic [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Revenues											5,182,000,000		5,082,000,000		4,052,000,000
Generation Midwest [Member]
Segment Reporting Information [Line Items]
Revenues											4,270,000,000		4,848,000,000		5,445,000,000
Revenue net of purchased power and fuel expense from external customers											2,585,039,304.94		2,974,000,000		3,547,000,000
Revenue net of purchased power and fuel expense from transactions with other operating segments of the same entity											960,695.06		24,000,000
Revenue net of purchased power and fuel expense, Total											2,586,000,000		2,998,000,000		3,547,000,000
Generation Midwest [Member] | Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Operating revenues from affiliates											(10,000,000)		24,000,000
Generation Midwest [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Revenues											4,280,000,000		4,824,000,000		5,445,000,000
Generation Midwest [Member] | Commonwealth Edison Co Affiliate [Member]
Segment Reporting Additional Information [Abstract]
Unrealized Gain (Loss) on Derivatives											7,000,000
Generation New England [Member]
Segment Reporting Information [Line Items]
Revenues											1,237,000,000		1,093,000,000		11,000,000
Revenue net of purchased power and fuel expense from external customers											216,782,130.36		151,000,000		9,000,000
Revenue net of purchased power and fuel expense from transactions with other operating segments of the same entity											(31,782,130.36)		45,000,000
Revenue net of purchased power and fuel expense, Total											185,000,000		196,000,000		9,000,000
Generation New England [Member] | Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Operating revenues from affiliates											(8,000,000)		45,000,000
Generation New England [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Revenues											1,245,000,000		1,048,000,000		11,000,000
Generation New York [Member]
Segment Reporting Information [Line Items]
Revenues											714,000,000		557,000,000		0
Revenue net of purchased power and fuel expense from external customers											14,398,673.46		101,000,000
Revenue net of purchased power and fuel expense from transactions with other operating segments of the same entity											(18,398,673.46)		(25,000,000)
Revenue net of purchased power and fuel expense, Total											(4,000,000)		76,000,000
Generation New York [Member] | Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Operating revenues from affiliates											(21,000,000)		(25,000,000)
Generation New York [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Revenues											735,000,000		582,000,000		0
Generation ERCOT [Member]
Segment Reporting Information [Line Items]
Revenues											1,216,000,000		1,367,000,000		575,000,000
Revenue net of purchased power and fuel expense from external customers											604,261,280.16		403,000,000		84,000,000
Revenue net of purchased power and fuel expense from transactions with other operating segments of the same entity											(168,261,280.16)		2,000,000
Revenue net of purchased power and fuel expense, Total											436,000,000		405,000,000		84,000,000
Generation ERCOT [Member] | Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Operating revenues from affiliates											(6,000,000)		2,000,000
Generation ERCOT [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Revenues											1,222,000,000		1,365,000,000		575,000,000
Generation Other Regions [Member]
Segment Reporting Information [Line Items]
Revenues											968,000,000		833,000,000		201,000,000
Revenue net of purchased power and fuel expense from external customers											333,648,771.48	[4]	53,000,000	[4]	(14,000,000)	[4]
Revenue net of purchased power and fuel expense from transactions with other operating segments of the same entity											(132,648,771.48)	[4]	78,000,000
Revenue net of purchased power and fuel expense, Total											201,000,000	[4]	131,000,000	[4]	(14,000,000)	[4]
Generation Other Regions [Member] | Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Operating revenues from affiliates											22,000,000		78,000,000
Generation Other Regions [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Revenues											946,000,000		755,000,000		201,000,000
Generation Reportable Segments Total [Member]
Segment Reporting Information [Line Items]
Revenues											13,609,000,000		13,736,000,000		10,284,000,000
Revenue net of purchased power and fuel expense from external customers											7,027,420,830.44		7,159,000,000		6,976,000,000
Revenue net of purchased power and fuel expense from transactions with other operating segments of the same entity											(353,420,830.44)		80,000,000
Revenue net of purchased power and fuel expense, Total											6,674,000,000		7,239,000,000		6,976,000,000
Generation Reportable Segments Total [Member] | Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Operating revenues from affiliates											(1,000,000)		80,000,000
Generation Reportable Segments Total [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Revenues											13,610,000,000		13,656,000,000		10,284,000,000
Generation Total Consolidated Group [Member]
Segment Reporting Information [Line Items]
Revenues											15,630,000,000		14,437,000,000		10,447,000,000
Revenue net of purchased power and fuel expense from external customers											7,433,011,008.07		7,376,000,000		6,858,000,000
Revenue net of purchased power and fuel expense from transactions with other operating segments of the same entity											0
Revenue net of purchased power and fuel expense, Total											7,432,611,007.56		7,376,000,000		6,858,000,000
Generation Total Consolidated Group [Member] | Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Operating revenues from affiliates											0		0
Generation Total Consolidated Group [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Revenues											15,630,000,000		14,437,000,000		10,447,000,000
Generation All Other Segments [Member]
Segment Reporting Information [Line Items]
Revenues											2,021,000,000		701,000,000		163,000,000
Revenue net of purchased power and fuel expense from external customers											405,590,177.629999	[5]	217,000,000	[5]	(118,000,000)	[5]
Revenue net of purchased power and fuel expense from transactions with other operating segments of the same entity											353,020,829.930001	[5]	(80,000,000)
Revenue net of purchased power and fuel expense, Total											758,611,007.56	[5]	137,000,000	[5]	(118,000,000)	[5]
Generation All Other Segments [Member] | Other Segments [Member]
Segment Reporting Information [Line Items]
Revenues											2,020,000,000
Generation All Other Segments [Member] | Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Operating revenues from affiliates											1,000,000
Generation All Other Segments [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Revenues													781,000,000		163,000,000
Generation All Other Segments [Member] | Baltimore Gas And Electric Company Affiliate [Member] | Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Operating revenues from affiliates													(80,000,000)
Commonwealth Edison Co [Member]
Segment Reporting Additional Information [Abstract]
Utility taxes													239,000,000		243,000,000
Commonwealth Edison Co [Member] | Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Operating revenues from affiliates													2,000,000		2,000,000
Commonwealth Edison Co [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Revenues											4,464,000,000		5,443,000,000		6,056,000,000
Operating revenues from affiliates											3,000,000
Income (loss) from continuing operations before income taxes											401,000,000		618,000,000		666,000,000
Depreciation and amortization											669,000,000		610,000,000		554,000,000
Operating Expenses											3,510,000,000		4,557,000,000		5,074,000,000
Interest Revenue (Expense), Net											579,000,000		307,000,000		345,000,000
Income taxes											152,000,000		239,000,000		250,000,000
Net income (loss)											249,000,000		379,000,000		416,000,000
Capital expenditures											1,433,000,000		1,246,000,000		1,028,000,000
Total assets	24,118,000,000					22,905,000,000					24,118,000,000		22,905,000,000
Commonwealth Edison Co [Member] | Commonwealth Edison Co Affiliate [Member]
Segment Reporting Additional Information [Abstract]
Utility taxes											241,000,000
PECO Energy Co [Member]
Segment Reporting Additional Information [Abstract]
Utility taxes											129,000,000		141,000,000		173,000,000
PECO Energy Co [Member] | Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Operating revenues from affiliates													3,000,000		5,000,000
PECO Energy Co [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Revenues											3,100,000,000		3,186,000,000		3,720,000,000
Operating revenues from affiliates											1,000,000
Income (loss) from continuing operations before income taxes											557,000,000		508,000,000		535,000,000
Depreciation and amortization											228,000,000		217,000,000		202,000,000
Operating Expenses											2,434,000,000				3,065,000,000
Interest Revenue (Expense), Net											115,000,000		123,000,000		134,000,000
Income taxes											162,000,000		127,000,000		146,000,000
Net income (loss)											395,000,000		381,000,000		389,000,000
Capital expenditures											537,000,000		422,000,000		481,000,000
Total assets	9,617,000,000					9,353,000,000					9,617,000,000		9,353,000,000
Baltimore Gas and Electric Company [Member]
Segment Reporting Information [Line Items]
Net income (loss)											210,000,000	[6]	(31,000,000)
Segment Reporting Additional Information [Abstract]
Utility taxes											82,000,000
Baltimore Gas and Electric Company [Member] | Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Operating revenues from affiliates													9,000,000		0
Baltimore Gas and Electric Company [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Revenues											3,065,000,000		2,091,000,000		0
Operating revenues from affiliates											13,000,000
Income (loss) from continuing operations before income taxes											344,000,000	[6]	(54,000,000)	[6]
Depreciation and amortization											348,000,000		238,000,000		0
Operating Expenses											2,616,000,000		2,053,000,000
Interest Revenue (Expense), Net											122,000,000	[6]	111,000,000	[6]
Income taxes											134,000,000	[6]	(23,000,000)	[6]
Capital expenditures											587,000,000		500,000,000
Total assets	7,861,000,000	[6]				7,506,000,000	[6]				7,861,000,000	[6]	7,506,000,000	[6]
Corporate and Other [Member] | Other Segments [Member]
Segment Reporting Information [Line Items]
Revenues											1,241,000,000		1,396,000,000
Operating revenues from affiliates													1,381,000,000		831,000,000
Income (loss) from continuing operations before income taxes											(191,000,000)	[7]	(325,000,000)	[7]	(59,000,000)	[7]
Depreciation and amortization											52,000,000		48,000,000		21,000,000
Operating Expenses											1,324,000,000		1,662,000,000		863,000,000
Interest Revenue (Expense), Net											183,000,000	[7]	86,000,000	[7]	77,000,000	[7]
Income taxes											(20,000,000)	[7]	(215,000,000)	[7]	9,000,000	[7]
Net income (loss)											(171,000,000)		(110,000,000)		(68,000,000)
Capital expenditures											86,000,000		67,000,000		42,000,000
Total assets	8,317,000,000					10,432,000,000					8,317,000,000		10,432,000,000
Corporate and Other [Member] | Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Revenues															830,000,000
Corporate and Other [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Operating revenues from affiliates											1,237,000,000
Operating Expenses													2,563,000,000
Segment Elimination [Member] | Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Revenues											(2,612,000,000)		(3,064,000,000)		(1,990,000,000)
Operating revenues from affiliates											(2,607,000,000)		(3,049,000,000)		(1,990,000,000)
Income (loss) from continuing operations before income taxes											(13,000,000)		(7,000,000)		(13,000,000)
Depreciation and amortization											0		0		0
Operating Expenses											(2,618,000,000)		(3,043,000,000)		(1,990,000,000)
Income taxes											1,000,000		(1,000,000)		(4,000,000)
Net income (loss)													(6,000,000)
Total assets	$ (11,221,000,000)					$ (12,316,000,000)					$ (11,221,000,000)		$ (12,316,000,000)

[1] Generation's utility tax represents gross receipts tax related to its retail operations and ComEd's, PECO's and BGE’s utility taxes represent municipal and state utility taxes and gross receipts taxes related to their operating revenues, respectively. The offsetting collection of utility taxes from customers is recorded in revenues on the Registrants' Consolidated Statements of Operations

[2] The intersegment profit associated with the sale of certain products and services by and between Exelon’s segments is not eliminated in consolidation due to the recognition of intersegment profit in accordance with regulatory accounting guidance. For Exelon, these amounts are included in operating revenues in the Consolidated Statement of Operations. See Note 3 - Regulatory Matters for additional information.

[3] Generation includes the six power marketing reportable segments shown below: Mid-Atlantic, Midwest, New England, New York, ERCOT and Other Regions. Intersegment revenues for Generation for the year ended December 31, 2013 include revenue from sales to PECO of $405 and sales to BGE of $455 million in the Mid-Atlantic region, and sales to ComEd of $506 in the Midwest region, net of $7 million related to the unrealized mark-to-market losses related to the ComEd swap, which eliminate upon consolidation. For the year ended December 31, 2012 include revenue from sales to PECO of $543 and sales to BGE of $322 million in the Mid-Atlantic region, and sales to ComEd of $795 in the Midwest region, net of $7 million related to the unrealized mark-to-market losses related to the ComEd swap, which eliminate upon consolidation. For the year ended 2011 intersegment revenues for Generation include revenue from sales to PECO of $508 million in the Mid-Atlantic region, and sales to ComEd of $653 million in the Midwest region.

[4] Other regions include the South, West and Canada, which are not considered individually significant.

[5] Other represents activities not allocated to a region. See text above for a description of included activities. Also includes amortization of intangible assets related to commodity contracts recorded at fair value of $767 million and $1,505 million for the years ended December 31, 2013 and 2012, respectively, and elimination of intersegment revenues.

[6] Amounts represent activity recorded at BGE from March 12, 2012, the closing date of the merger, through December 31, 2013.

[7] Other primarily includes Exelon’s corporate operations, shared service entities and other financing and investment activities.