Variable Interest Entities (Details) (USD $)	12 Months Ended
	Dec. 31, 2013		Dec. 31, 2012		Dec. 31, 2011
Consolidated Variable Interest Entities Disclosure [Abstract]
Current Assets	$ 484,000,000		$ 550,000,000
Non Current Assets	1,905,000,000		1,719,000,000
Total Assets	2,389,000,000	[1]	2,269,000,000	[1],[2]
Current Liabilities	566,000,000		684,000,000
Non Current Liabilites	774,000,000		775,000,000
Total Liabilities	1,340,000,000	[1]	1,459,000,000	[1],[2]
Deferred tax assets	0		58,000,000
Variable Interest Entity, Not Primary Beneficiary, Disclosures [Abstract]
Number of Variable Interest Entities not consolidated by equity holders	8		9
Number Of Variable Interest Entities Consolidated	4		5
Variable Interest Entity Nonconsolidated Carrying Amount Assets Liabilities And Other Information [Abstract]
Total assets	460,000,000	[3]	740,000,000	[3]
Total liabilities	140,000,000	[3]	333,000,000	[3]
Our ownership interest	86,000,000	[3]	97,000,000	[3]
Other ownership interests	234,000,000	[3]	310,000,000	[3]
Variable Interest Entity Nonconsolidated Carrying Amount Assets Liabilities And Other Information Footnotes [Abstract]
Gross pledged assets	614,000,000		734,000,000
Pledged assets liabilities offset	414,000,000		564,000,000
Commercial Agreement Variable Interest Entities [Member]
Variable Interest Entity Nonconsolidated Carrying Amount Assets Liabilities And Other Information [Abstract]
Total assets	128,000,000	[3]	386,000,000	[3]
Total liabilities	17,000,000	[3]	219,000,000	[3]
Our ownership interest	0	[3]	0	[3]
Other ownership interests	111,000,000	[3]	167,000,000	[3]
Equity Method Investment Variable Interest Entities [Member]
Variable Interest Entity Nonconsolidated Carrying Amount Assets Liabilities And Other Information [Abstract]
Total assets	332,000,000	[3]	354,000,000	[3]
Total liabilities	123,000,000	[3]	114,000,000	[3]
Our ownership interest	86,000,000	[3]	97,000,000	[3]
Other ownership interests	123,000,000	[3]	143,000,000	[3]
Letter of Credit [Member] | Maximum [Member]
Variable Interest Entity Nonconsolidated Carrying Amount Assets Liabilities And Other Information [Abstract]
Our maximum exposure to loss			5,000,000
Letter of Credit [Member] | Maximum [Member] | Commercial Agreement Variable Interest Entities [Member]
Variable Interest Entity Nonconsolidated Carrying Amount Assets Liabilities And Other Information [Abstract]
Our maximum exposure to loss			5,000,000
Letter of Credit [Member] | Maximum [Member] | Equity Method Investment Variable Interest Entities [Member]
Variable Interest Entity Nonconsolidated Carrying Amount Assets Liabilities And Other Information [Abstract]
Our maximum exposure to loss			0
Investments [Member]
Variable Interest Entity Nonconsolidated Carrying Amount Assets Liabilities And Other Information [Abstract]
Other ownership interests	74,000,000
Investments [Member] | Commercial Agreement Variable Interest Entities [Member]
Variable Interest Entity Nonconsolidated Carrying Amount Assets Liabilities And Other Information [Abstract]
Other ownership interests	7,000,000
Investments [Member] | Equity Method Investment Variable Interest Entities [Member]
Variable Interest Entity Nonconsolidated Carrying Amount Assets Liabilities And Other Information [Abstract]
Other ownership interests	67,000,000
Investments [Member] | Maximum [Member]
Variable Interest Entity Nonconsolidated Carrying Amount Assets Liabilities And Other Information [Abstract]
Our maximum exposure to loss			77,000,000
Investments [Member] | Maximum [Member] | Commercial Agreement Variable Interest Entities [Member]
Variable Interest Entity Nonconsolidated Carrying Amount Assets Liabilities And Other Information [Abstract]
Our maximum exposure to loss			0
Investments [Member] | Maximum [Member] | Equity Method Investment Variable Interest Entities [Member]
Variable Interest Entity Nonconsolidated Carrying Amount Assets Liabilities And Other Information [Abstract]
Our maximum exposure to loss			77,000,000
Contract Intangible Asset [Member]
Variable Interest Entity Nonconsolidated Carrying Amount Assets Liabilities And Other Information [Abstract]
Other ownership interests	9,000,000
Contract Intangible Asset [Member] | Commercial Agreement Variable Interest Entities [Member]
Variable Interest Entity Nonconsolidated Carrying Amount Assets Liabilities And Other Information [Abstract]
Other ownership interests	9,000,000
Contract Intangible Asset [Member] | Equity Method Investment Variable Interest Entities [Member]
Variable Interest Entity Nonconsolidated Carrying Amount Assets Liabilities And Other Information [Abstract]
Other ownership interests	0
Contract Intangible Asset [Member] | Maximum [Member]
Variable Interest Entity Nonconsolidated Carrying Amount Assets Liabilities And Other Information [Abstract]
Our maximum exposure to loss			8,000,000
Contract Intangible Asset [Member] | Maximum [Member] | Commercial Agreement Variable Interest Entities [Member]
Variable Interest Entity Nonconsolidated Carrying Amount Assets Liabilities And Other Information [Abstract]
Our maximum exposure to loss			8,000,000
Contract Intangible Asset [Member] | Maximum [Member] | Equity Method Investment Variable Interest Entities [Member]
Variable Interest Entity Nonconsolidated Carrying Amount Assets Liabilities And Other Information [Abstract]
Our maximum exposure to loss			0
Payment Guarantee [Member]
Variable Interest Entity Nonconsolidated Carrying Amount Assets Liabilities And Other Information [Abstract]
Other ownership interests	5,000,000
Payment Guarantee [Member] | Commercial Agreement Variable Interest Entities [Member]
Variable Interest Entity Nonconsolidated Carrying Amount Assets Liabilities And Other Information [Abstract]
Other ownership interests	0
Payment Guarantee [Member] | Equity Method Investment Variable Interest Entities [Member]
Variable Interest Entity Nonconsolidated Carrying Amount Assets Liabilities And Other Information [Abstract]
Other ownership interests	5,000,000
Payment Guarantee [Member] | Maximum [Member]
Variable Interest Entity Nonconsolidated Carrying Amount Assets Liabilities And Other Information [Abstract]
Our maximum exposure to loss			5,000,000
Payment Guarantee [Member] | Maximum [Member] | Commercial Agreement Variable Interest Entities [Member]
Variable Interest Entity Nonconsolidated Carrying Amount Assets Liabilities And Other Information [Abstract]
Our maximum exposure to loss			0
Payment Guarantee [Member] | Maximum [Member] | Equity Method Investment Variable Interest Entities [Member]
Variable Interest Entity Nonconsolidated Carrying Amount Assets Liabilities And Other Information [Abstract]
Our maximum exposure to loss			5,000,000
Net assets pledged for Zion Station decommissioning
Variable Interest Entity Nonconsolidated Carrying Amount Assets Liabilities And Other Information [Abstract]
Our maximum exposure to loss	44,000,000	[4]
Net assets pledged for Zion Station decommissioning | Commercial Agreement Variable Interest Entities [Member]
Variable Interest Entity Nonconsolidated Carrying Amount Assets Liabilities And Other Information [Abstract]
Our maximum exposure to loss	44,000,000	[4]
Net assets pledged for Zion Station decommissioning | Equity Method Investment Variable Interest Entities [Member]
Variable Interest Entity Nonconsolidated Carrying Amount Assets Liabilities And Other Information [Abstract]
Our maximum exposure to loss	0	[4]
Net assets pledged for Zion Station decommissioning | Maximum [Member]
Variable Interest Entity Nonconsolidated Carrying Amount Assets Liabilities And Other Information [Abstract]
Our maximum exposure to loss			50,000,000	[4]
Net assets pledged for Zion Station decommissioning | Maximum [Member] | Commercial Agreement Variable Interest Entities [Member]
Variable Interest Entity Nonconsolidated Carrying Amount Assets Liabilities And Other Information [Abstract]
Our maximum exposure to loss			50,000,000	[4]
Net assets pledged for Zion Station decommissioning | Maximum [Member] | Equity Method Investment Variable Interest Entities [Member]
Variable Interest Entity Nonconsolidated Carrying Amount Assets Liabilities And Other Information [Abstract]
Our maximum exposure to loss			0	[4]
Retail Gas Customer Supply Operation [Member]
Variable Interest Entity Nonconsolidated Carrying Amount Assets Liabilities And Other Information [Abstract]
Total assets			146,000,000
Total liabilities			42,000,000
Exelon Generation Co L L C [Member]
Consolidated Variable Interest Entities Disclosure [Abstract]
Current Assets	446,000,000		519,000,000
Non Current Assets	1,884,000,000		1,680,000,000
Total Assets	2,330,000,000		2,199,000,000	[2]
Current Liabilities	481,000,000		612,000,000
Non Current Liabilites	562,000,000		470,000,000
Total Liabilities	1,043,000,000		1,082,000,000	[2]
Projects with significant economic power	9
Variable Interest Entity Nonconsolidated Carrying Amount Assets Liabilities And Other Information Footnotes [Abstract]
Gross pledged assets	458,000,000		614,000,000
Pledged assets liabilities offset	414,000,000		564,000,000
Exelon Generation Co L L C [Member] | Minimum [Member]
Consolidated Variable Interest Entities Disclosure [Abstract]
Minority Interest Ownership Percentage By Noncontrolling Owners	1.00%
Exelon Generation Co L L C [Member] | Maximum [Member]
Consolidated Variable Interest Entities Disclosure [Abstract]
Minority Interest Ownership Percentage By Noncontrolling Owners	6.00%
Exelon Generation Co L L C [Member] | Retail Gas Customer Supply Operation [Member]
Consolidated Variable Interest Entities Disclosure [Abstract]
Ownership percentage, consolidated variable interest entity (as a percent)	100.00%
Parental guarantee provided	75,000,000
Exelon Generation Co L L C [Member] | Solar Project Limited Liability Companies [Member]
Consolidated Variable Interest Entities Disclosure [Abstract]
Ownership percentage, consolidated variable interest entity (as a percent)	100.00%
Business Acquisitions, Megawatts Acquired	230
Aggregate amount of debt with third parties	536,000,000
Exelon Generation Co L L C [Member] | Wind Project Limited Liability Companies [Member]
Consolidated Variable Interest Entities Disclosure [Abstract]
Ownership percentage, consolidated variable interest entity (as a percent)	100.00%
Projects with significant economic power	10
Exelon Generation Co L L C [Member] | Wind Project Limited Liability Companies [Member] | Minimum [Member]
Consolidated Variable Interest Entities Disclosure [Abstract]
Minority Interest Ownership Percentage By Noncontrolling Owners	99.00%
Exelon Generation Co L L C [Member] | Wind Project Limited Liability Companies [Member] | Maximum [Member]
Consolidated Variable Interest Entities Disclosure [Abstract]
Minority Interest Ownership Percentage By Noncontrolling Owners	94.00%
PECO Energy Co [Member]
Variable Interest Entity Nonconsolidated Carrying Amount Assets Liabilities And Other Information Footnotes [Abstract]
Amount of PECO's stranded costs authorized to be recovered by the PAPUC	5,000,000,000
Baltimore Gas and Electric Company [Member]
Consolidated Variable Interest Entities Disclosure [Abstract]
Current Assets	28,000,000		30,000,000
Non Current Assets	3,000,000
Total Assets	31,000,000		30,000,000
Current Liabilities	74,000,000		71,000,000
Non Current Liabilites	195,000,000		265,000,000
Total Liabilities	269,000,000		336,000,000
Deferred tax assets	0
Remittance of payments received from customers for rate stabilization to BondCo.	$ 83,000,000		$ 85,000,000		$ 92,000,000

[1] ________________ Includes certain purchase accounting adjustments not pushed down to the BGE standalone entity.

[2] Includes total assets of $146 million and total liabilities of $42 million as of December 31, 2012 related to a retail supply company that is not a consolidated VIE as of December 31, 2013. See additional information below.

[3] These items represent amounts on the unconsolidated VIE balance sheets, not on Exelon’s or Generation’s Consolidated Balance Sheets. These items are included to provide information regarding the relative size of the unconsolidated VIEs.

[4] These items represent amounts on Exelon’s and Generation’s Consolidated Balance Sheets related to the asset sale agreement with ZionSolutions, LLC. The net assets pledged for Zion Station decommissioning includes gross pledged assets of $458 million and $614 million as of December 31, 2013 and December 31, 2012, respectively; offset by payables to ZionSolutions LLC of $414 million and $564 million as of December 31, 2013 and December 31, 2012, respectively. These items are included to provide information regarding the relative size of the ZionSolutions LLC unconsolidated VIE. See Note 15 – Asset Retirement Obligations for further discussion.