Related Party Transactions (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012		Dec. 31, 2011		Dec. 31, 2010
Schedule of Equity Method Investments [Line Items]
Percentage of ownership interest in CENG (as a percent)	1.00%
Related Party Income Statement Activity [Abstract]
Operating revenues from affiliates	$ 48.00		$ 9.00		$ 6.00
Total fuel purchases from related parties	922.00		137.00		144.00
Charitable contributions to Exelon Foundation	7.00	[1]	0	[1]	10.00	[1]
Total interest expense to affiliates, net	25.00		25.00		25.00
Total income (loss) in equity method investments	(91.00)		(1.00)		0
Cash dividends paid to parent	1,716.00		1,393.00		1,389.00
Related Party Balance Sheet [Abstract]
Investments in affiliates	22.00		15.00
Total payables to affiliates (current)	88.00		5.00
Mark-to-market derivative liabilities with affiliate (current liabilities)	0
Long-term debt to financing trusts	648.00		390.00
Equity Method Investment Summarized Financial Information[Abstract]
Amortization of energy contract assets and liabilities	1,110.00
ComEd Financing Three Affiliate [Member]
Related Party Income Statement Activity [Abstract]
Total interest expense to affiliates, net	(13.00)		(13.00)		(13.00)
Related Party Balance Sheet [Abstract]
Investments in affiliates	6.00		6.00
Total payables to affiliates (current)	4.00		4.00
Long-term debt to financing trusts	206.00		206.00
Conemaugh Fuels LLC Affiliate [Member]
Related Party Income Statement Activity [Abstract]
Total fuel purchases from related parties	68.00		69.00		70.00
Keystone Fuels LLC Affiliate [Member]
Related Party Income Statement Activity [Abstract]
Total fuel purchases from related parties	61.00		68.00		74.00
NuStart Energy Development LLC Affiliate [Member]
Related Party Income Statement Activity [Abstract]
Total income (loss) in equity method investments	0		0
Constellation Energy Nuclear Group Llc Affiliate [Member]
Related Party Income Statement Activity [Abstract]
Operating revenues from affiliates	42.00	[2]
Total fuel purchases from related parties	793.00	[3]
Related Party Balance Sheet [Abstract]
Total receivables from affiliates (current)	16.00	[2]	0	[2]
Total payables to affiliates (current)	83.00	[3]	0	[3]
CENG Equity Investment Income Affiliate [Member]
Related Party Income Statement Activity [Abstract]
Total income (loss) in equity method investments	73.00
Amortization Of Basis Difference In Ceng Affiliate [Member]
Related Party Income Statement Activity [Abstract]
Total income (loss) in equity method investments	(172.00)	[4]
Other Affiliate [Member]
Related Party Income Statement Activity [Abstract]
Total interest expense to affiliates, net	0		0		0
Total income (loss) in equity method investments	8.00		(1.00)
PECO Energy Co Affiliate [Member]
Related Party Income Statement Activity [Abstract]
Operating revenues from affiliates	6.00	[5]	9.00	[5]	6.00	[5]
PECO Energy Capital Corporation Affiliate [Member]
Related Party Balance Sheet [Abstract]
Investments in affiliates	4.00		4.00
PECO Trust Three Affiliate [Member]
Related Party Income Statement Activity [Abstract]
Total interest expense to affiliates, net	(6.00)		(6.00)		(6.00)
Related Party Balance Sheet [Abstract]
Total payables to affiliates (current)	1.00		1.00
Long-term debt to financing trusts	81.00		81.00
PECO Trust Four Affiliate [Member]
Related Party Income Statement Activity [Abstract]
Total interest expense to affiliates, net	(6.00)		(6.00)		(6.00)
Related Party Balance Sheet [Abstract]
Investments in affiliates	4.00		5.00
Total payables to affiliates (current)	0		0
Long-term debt to financing trusts	103.00		103.00
BGE Capital Trust II [Member]
Related Party Balance Sheet [Abstract]
Investments in affiliates	8.00		0
Long-term debt to financing trusts	258.00		0
Exelon Generation Co L L C [Member]
Related Party Income Statement Activity [Abstract]
Operating revenues from affiliates	1,702.00		1,161.00		3,102.00
Total fuel purchases from related parties	930.00		138.00		145.00
Operating and maintenance from affiliate	630.00		321.00		291.00
Total income (loss) in equity method investments	(91.00)		(1.00)		0
Cash distribution paid to member	1,626.00		172.00		1,508.00
Contributions from member	48.00		30.00		62.00
Related Party Balance Sheet [Abstract]
Mark-to-market derivative assets with affiliates	226.00		503.00
Total receivables from affiliates (current)	141.00		109.00
Mark-to-market derivative assets with affiliate (noncurrent assets)	0		191.00
Total payables to affiliates (current)	193.00		58.00
Mark-to-market derivative liabilities with affiliate (current liabilities)	0
Total payables to affiliates (noncurrent)	2,397.00		2,222.00
Equity Method Investment Summarized Financial Information[Abstract]
Purchase of nuclear output by EDF (as a percent)	49.99%
Amortization of energy contract assets and liabilities	1,110.00
Exelon Generation Co L L C [Member] | Exelon Business Services Co Affiliate [Member]
Related Party Income Statement Activity [Abstract]
Operating revenues from affiliates	0		0		0
Operating and maintenance from affiliate	625.00	[6]	314.00	[6]	285.00	[6]
Related Party Balance Sheet [Abstract]
Total payables to affiliates (current)	77.00	[6]	51.00	[6]
Exelon Generation Co L L C [Member] | Commonwealth Edison Co Affiliate [Member]
Related Party Income Statement Activity [Abstract]
Operating revenues from affiliates	795.00	[7]	653.00	[7]	1,010.00	[7]
Total fuel purchases from related parties	0		0		0
Operating and maintenance from affiliate	2.00	[8]	2.00	[8]	2.00	[8]
Related Party Balance Sheet [Abstract]
Mark-to-market derivative assets with affiliates	226.00	[9]	503.00	[9]
Total receivables from affiliates (current)	54.00	[10],[7]	70.00	[10],[7]
Mark-to-market derivative assets with affiliate (noncurrent assets)	0	[9]	191.00	[9]
Total payables to affiliates (noncurrent)	2,037.00	[11]	1,857.00	[11]
Related Party Transaction Footnote Information [Abstract]
Swap Contract Receivable	53.00		53.00
Exelon Generation Co L L C [Member] | Conemaugh Fuels LLC Affiliate [Member]
Related Party Income Statement Activity [Abstract]
Total fuel purchases from related parties	68.00		69.00		70.00
Exelon Generation Co L L C [Member] | Exelon Corporation Affiliate [Member]
Related Party Balance Sheet [Abstract]
Total receivable from affiliates (noncurrent)	1.00		1.00
Total payables to affiliates (current)	33.00	[12]	7.00	[12]
Exelon Generation Co L L C [Member] | Keystone Fuels LLC Affiliate [Member]
Related Party Income Statement Activity [Abstract]
Total fuel purchases from related parties	61.00		68.00		74.00
Exelon Generation Co L L C [Member] | Constellation Energy Nuclear Group Llc Affiliate [Member]
Related Party Income Statement Activity [Abstract]
Operating revenues from affiliates	42.00	[2]
Total fuel purchases from related parties	793.00	[3]
Operating and maintenance from affiliate	0
Related Party Balance Sheet [Abstract]
Total payables to affiliates (current)	83.00	[3]	0	[3]
Exelon Generation Co L L C [Member] | Constellation Energy Nuclear Group Llc Affiliate [Member] | Power Purchase Agreement [Member] | Minimum [Member]
Equity Method Investment Summarized Financial Information[Abstract]
Required purchases of power from CENG's nuclear plants not sold to third parties (as a percent)	85.00%
Exelon Generation Co L L C [Member] | Constellation Energy Nuclear Group Llc Affiliate [Member] | Power Purchase Agreement [Member] | Maximum [Member]
Equity Method Investment Summarized Financial Information[Abstract]
Required purchases of power from CENG's nuclear plants not sold to third parties (as a percent)	90.00%
Exelon Generation Co L L C [Member] | CENG Equity Investment Income Affiliate [Member]
Related Party Income Statement Activity [Abstract]
Total income (loss) in equity method investments	73.00
Exelon Generation Co L L C [Member] | Amortization Of Basis Difference In Ceng Affiliate [Member]
Related Party Income Statement Activity [Abstract]
Total income (loss) in equity method investments	(172.00)	[13]
Exelon Generation Co L L C [Member] | PECO Energy Co Affiliate [Member]
Related Party Income Statement Activity [Abstract]
Operating revenues from affiliates	543.00	[14]	508.00	[14]	2,092.00	[14]
Total fuel purchases from related parties	0		1.00		1.00
Operating and maintenance from affiliate	3.00	[8]	5.00	[8]	4.00	[8]
Related Party Balance Sheet [Abstract]
Total receivables from affiliates (current)	56.00	[14]	39.00	[14]
Total payables to affiliates (noncurrent)	360.00	[11]	365.00	[11]
Exelon Generation Co L L C [Member] | Baltimore Gas And Electric Company Affiliate [Member]
Related Party Income Statement Activity [Abstract]
Operating revenues from affiliates	322.00	[15]
Total fuel purchases from related parties	8.00
Related Party Balance Sheet [Abstract]
Total receivables from affiliates (current)	31.00	[15]	0	[15]
Exelon Generation Co L L C [Member] | Qualifying Facilities And Domestic Power Projects Affiliate [Member]
Related Party Income Statement Activity [Abstract]
Total income (loss) in equity method investments	8.00		(1.00)
Exelon Generation Co L L C [Member] | CENG [Member]
Schedule of Equity Method Investments [Line Items]
Percentage of ownership interest in CENG (as a percent)	50.01%
Basis difference in investment in CENG	204.00
Commonwealth Edison Co [Member]
Related Party Income Statement Activity [Abstract]
Operating revenues from affiliates	2.00		2.00		2.00
Purchased power from affiliate	789.00		653.00		1,010.00
Operating and maintenance from affiliate	163.00		158.00		152.00
Total interest expense to affiliates, net	13.00		15.00		13.00
Total income (loss) in equity method investments	0		0		0
Cash dividends paid to parent	105.00		300.00		310.00
Contributions from parent	0		0		2.00
Non cash contributions from parent	11.00		11.00
Intercompany non-cash allocation of tax benefit					11.00
Related Party Balance Sheet [Abstract]
Total receivable from affiliates (noncurrent)	2,039.00		1,860.00
Prepaid voluntary employee beneficiary association trust	10.00	[16]	12.00	[16]
Investments in affiliates	6.00		6.00
Total payables to affiliates (current)	97.00		111.00
Mark-to-market derivative liabilities with affiliate (current liabilities)	226.00		503.00
Mark-to-market derivative liabilities with affiliate (noncurrent liabilities)	0		191.00
Commonwealth Edison Co [Member] | Exelon Business Services Co Affiliate [Member]
Related Party Income Statement Activity [Abstract]
Operating and maintenance from affiliate	163.00	[17]	158.00	[17]	152.00	[17]
Capitalized Costs	92.00	[17]	85.00	[17]	84.00	[17]
Related Party Balance Sheet [Abstract]
Total payables to affiliates (current)	35.00	[17]	35.00	[17]
Commonwealth Edison Co [Member] | ComEd Financing Three Affiliate [Member]
Related Party Income Statement Activity [Abstract]
Total interest expense to affiliates, net	13.00		13.00		13.00
Related Party Balance Sheet [Abstract]
Investments in affiliates	6.00		6.00
Total payables to affiliates (current)	4.00		4.00
Long-term debt to financing trusts	206.00		206.00
Commonwealth Edison Co [Member] | Exelon Corporation Affiliate [Member]
Related Party Income Statement Activity [Abstract]
Total interest expense to affiliates, net	0		2.00		0
Related Party Balance Sheet [Abstract]
Total payables to affiliates (current)	0		0
Commonwealth Edison Co [Member] | Exelon Generation Co LLC Affiliate [Member]
Related Party Income Statement Activity [Abstract]
Operating revenues from affiliates	2.00		2.00		2.00
Purchased power from affiliate	789.00	[18]	653.00	[18]	1,010.00	[18]
Related Party Balance Sheet [Abstract]
Total receivable from affiliates (noncurrent)	2,037.00	[19]	1,857.00	[19]
Total payables to affiliates (current)	54.00	[18],[20]	70.00	[18],[20]
Mark-to-market derivative liabilities with affiliate (current liabilities)	226.00	[21]	503.00	[21]
Mark-to-market derivative liabilities with affiliate (noncurrent liabilities)	0	[21]	191.00	[21]
Related Party Transaction Footnote Information [Abstract]
Swap Contract Payable	53.00		53.00
Commonwealth Edison Co [Member] | Other Affiliate [Member]
Related Party Balance Sheet [Abstract]
Total receivable from affiliates (noncurrent)	2.00		3.00
Total payables to affiliates (current)	4.00		2.00
PECO Energy Co [Member]
Related Party Income Statement Activity [Abstract]
Operating revenues from affiliates	3.00		5.00		5.00
Purchased power from affiliate	533.00		495.00		2,085.00
Operating and maintenance from affiliate	111.00		96.00		89.00
Total interest expense to affiliates, net	12.00		12.00		12.00
Cash dividends paid to parent	343.00		348.00		224.00
Contributions from parent	9.00		18.00		43.00
Repayment of receivable from parent	0		0		180.00
Related Party Balance Sheet [Abstract]
Total receivable from affiliates (noncurrent)	360.00		365.00
Prepaid voluntary employee beneficiary association trust	2.00	[22]	3.00	[22]
Investments in affiliates	8.00		8.00
Total payables to affiliates (current)	76.00		62.00
Mark-to-market derivative liabilities with affiliate (current liabilities)	0		0
Mark-to-market derivative liabilities with affiliate (noncurrent liabilities)	0		0
Long-term debt to financing trusts	184.00		184.00
Shareholders' equity - receivable from parent	0		0
PECO Energy Co [Member] | Exelon Business Services Co Affiliate [Member]
Related Party Income Statement Activity [Abstract]
Operating and maintenance from affiliate	107.00	[23]	92.00	[23]	89.00	[23]
Capitalized Costs	54.00	[23]	60.00	[23]	40.00	[23]
Related Party Balance Sheet [Abstract]
Total payables to affiliates (current)	18.00	[23]	21.00	[23]
PECO Energy Co [Member] | Exelon Corporation Affiliate [Member]
Related Party Balance Sheet [Abstract]
Total payables to affiliates (current)	1.00		1.00
PECO Energy Co [Member] | Exelon Generation Co LLC Affiliate [Member]
Related Party Income Statement Activity [Abstract]
Operating revenues from affiliates	3.00	[24]	5.00	[24]	5.00	[24]
Purchased power from affiliate	533.00	[25]	495.00	[25]	2,085.00	[25]
Operating and maintenance from affiliate	4.00		4.00		0
Related Party Balance Sheet [Abstract]
Total receivable from affiliates (noncurrent)	360.00	[26]	365.00	[26]
Total payables to affiliates (current)	56.00	[25]	39.00	[25]
Mark-to-market derivative liabilities with affiliate (current liabilities)	0		0
PECO Energy Co [Member] | Other Affiliate [Member]
Related Party Income Statement Activity [Abstract]
Total interest expense to affiliates, net	0		0		0
PECO Energy Co [Member] | PECO Energy Capital Corporation Affiliate [Member]
Related Party Balance Sheet [Abstract]
Investments in affiliates	4.00		4.00
PECO Energy Co [Member] | PECO Trust Three Affiliate [Member]
Related Party Income Statement Activity [Abstract]
Total interest expense to affiliates, net	6.00		6.00		6.00
Related Party Balance Sheet [Abstract]
Total payables to affiliates (current)	1.00		1.00
Long-term debt to financing trusts	81.00		81.00
PECO Energy Co [Member] | PECO Trust Four Affiliate [Member]
Related Party Income Statement Activity [Abstract]
Total interest expense to affiliates, net	6.00		6.00		6.00
Related Party Balance Sheet [Abstract]
Investments in affiliates	4.00		4.00
Long-term debt to financing trusts	103.00		103.00
Baltimore Gas and Electric Company [Member]
Related Party Income Statement Activity [Abstract]
Operating revenues from affiliates	10.00		8.00		7.00
Purchased power from affiliate	396.00		348.00		428.00
Operating and maintenance from affiliate	106.00		150.00		126.00
Cash dividends paid to parent	0		85.00		0
Contributions from parent	66.00		0		0
Related Party Balance Sheet [Abstract]
Investments in affiliates	8.00		8.00
Total payables to affiliates (current)	65.00		41.00
Baltimore Gas and Electric Company [Member] | Exelon Business Services Co Affiliate [Member]
Related Party Income Statement Activity [Abstract]
Operating and maintenance from affiliate	106.00	[27]	150.00	[27]	126.00	[27]
Capitalized Costs	21.00	[27]	29.00	[27]	49.00	[27]
Related Party Balance Sheet [Abstract]
Total payables to affiliates (current)	12.00	[27]
Baltimore Gas and Electric Company [Member] | Commonwealth Edison Co Affiliate [Member]
Related Party Balance Sheet [Abstract]
Total payables to affiliates (current)	3.00
Baltimore Gas and Electric Company [Member] | Exelon Corporation Affiliate [Member]
Related Party Balance Sheet [Abstract]
Total payables to affiliates (current)	17.00	[28]
Baltimore Gas and Electric Company [Member] | Exelon Generation Co LLC Affiliate [Member]
Related Party Income Statement Activity [Abstract]
Operating revenues from affiliates	10.00	[29]	8.00	[29]	7.00	[29]
Purchased power from affiliate	396.00	[30]	348.00	[30]	428.00	[30]
Related Party Balance Sheet [Abstract]
Total payables to affiliates (current)	31.00	[30]	41.00	[30]
Baltimore Gas and Electric Company [Member] | PECO Energy Co Affiliate [Member]
Related Party Balance Sheet [Abstract]
Total payables to affiliates (current)	2.00
Baltimore Gas and Electric Company [Member] | BGE Capital Trust II [Member]
Related Party Balance Sheet [Abstract]
Investments in affiliates	8.00
Long-term debt to financing trusts	$ 258.00

[1] Exelon Foundation is a nonconsolidated not-for-profit Illinois corporation. The Exelon Foundation was established in 2007 to serve educational and environmental philanthropic purposes and does not serve a direct business or political purpose of Exelon

[2] Exelon has a shared services agreement (SSA) with CENG, which expires in 2017.  Under the SSA, BSC provides a variety of support services to CENG.  Pursuant to an agreement between Exelon and EDF, the pricing in the SSA for services reflect actual costs determined on the same basis that BSC charges its affiliates for similar services.

[3] A subsidiary of Generation has an agreement under which it is purchasing 85-90% of the output of CENG’s nuclear plants that is not sold to third parties under pre-existing firm and unit contingent PPAs through 2014. Beginning on January 1, 2015 and continuing to the end of the life of the respective plants, Generation will purchase on a unit contingent basis 50.01% of the output of CENG’s nuclear plants, and EDF will purchase on a unit contingent basis 49.99% of the output.

[4] As of March 12, 2012, Generation had an initial basis difference of approximately $204 million between the initial carrying value of its investment in CENG and its underlying equity in CENG.  This basis difference resulted from the requirement to record the investment in CENG at fair value under purchase accounting while the underlying assets and liabilities within CENG continue to be accounted for on a historical cost basis. Generation is amortizing this basis difference over the respective useful lives of the assets and liabilities of CENG or as those assets and liabilities impact the earnings of CENG. In future periods, Generation may be eligible for distributions from CENG in excess of its 50.01% ownership interest based on tax sharing provisions contained in the operating agreement for CENG. Through purchase accounting, Generation recorded the fair value of expected future distributions. Generation will record these distributions when realized as a reduction in its investment in CENG. Distributions realized in excess of the fair value recorded would be recorded in earnings in the period earned.

[5] The intersegment profit associated with Generation's sale of AECs to PECO is not eliminated in consolidation due to the recognition of intersegment profit in accordance with regulatory accounting guidance. See Note 3 - Regulatory Matters for additional information.

[6] Generation 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. A portion of such services is capitalized.

[7] Generation has an ICC-approved RFP contract with ComEd to provide a portion of ComEd's electricity supply requirements. Generation also sells RECs to ComEd. In addition, Generation had revenue from ComEd associated with the settled portion of the financial swap contract established as part of the Illinois Settlement. See Note 3 - Regulatory Matters for additional information.

[8] Generation requires electricity for its own use at its generating stations. Generation purchases electricity and distribution and transmission services from PECO and only distribution and transmission services from ComEd for the delivery of electricity to its generating stations.

[9] Represents the fair value of Generation's five-year financial swap contract with ComEd.

[10] Generation had a $53 million and $53 million receivable from ComEd at December 31, 2012 and 2011, respectively, associated with the completed portion of the financial swap contract entered into as part of the Illinois Settlement. See Note 3 - Regulatory Matters and Note 10 - Derivative Financial Instruments for additional information.

[11] Generation has long-term payables to ComEd and PECO as a result of the nuclear decommissioning contractual construct whereby, to the extent NDT funds are greater than the underlying ARO at the end of decommissioning, such amounts are due back to ComEd and PECO, as applicable, for payment to their respective customers. See Note 13 - Asset Retirement Obligations.

[12] In order to facilitate payment processing, Exelon processes certain invoice payments on behalf of Generation.

[13] As of March 12, 2012, Generation had an initial basis difference of approximately $204 million between the initial carrying value of its investment in CENG and its underlying equity in CENG.  This basis difference resulted from the requirement to record the investment in CENG at fair value under purchase accounting while the underlying assets and liabilities within CENG continue to be accounted for on a historical cost basis. Generation is amortizing this basis difference over the respective useful lives of the assets and liabilities of CENG or as those assets and liabilities impact the earnings of CENG. In future periods, Generation may be eligible for distributions from CENG in excess of its 50.01% ownership interest based on tax sharing provisions contained in the operating agreement for CENG. Through purchase accounting, Generation recorded the fair value of expected future distributions. Generation will record these distributions when realized as a reduction in its investment in CENG. Distributions realized in excess of the fair value recorded would be recorded in earnings in the period earned.

[14] Generation had a PPA with PECO to provide the full energy requirements to PECO through 2010. In addition, Generation has five-year and ten-year agreements with PECO to sell non-solar and solar AECs, respectively. See Note 3 - Regulatory Matters for additional information.

[15] Generation provides a portion of BGE’s energy requirements under its MDPSC-approved market-based SOS and gas commodity programs. See Note 3 - Regulatory Matters for additional information.

[16] The voluntary employee benefit association trusts covering active employees are included in corporate operations and are funded by the operating segments. A prepayment to the active welfare plans has accumulated due to actuarially determined contribution rates, which are the basis for ComEd's contributions to the plans, being higher than actual claim expense incurred by the plans over time. The prepayment is included in other current assets.

[17] ComEd 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. A portion of such services is capitalized.

[18] ComEd procures a portion of its electricity supply requirements from Generation under an ICC-approved RFP contract. ComEd also purchases RECs from Generation. In addition, purchased power expense includes the settled portion of the financial swap contract with Generation established as part of the Illinois Settlement Legislation. See Note 3 - Regulatory Matters and Note 10 - Derivative Financial Instruments for additional information.

[19] ComEd has a long-term receivable from Generation as a result of the nuclear decommissioning contractual construct for generating facilities previously owned by ComEd. To the extent the assets associated with decommissioning are greater than the applicable ARO at the end of decommissioning, such amounts are due back to ComEd for payment to ComEd's customers.

[20] ComEd had a $53 million and $53 million payable to Generation at December 31, 2012 and 2011, respectively, associated with the completed portion of the financial swap contract entered into as part of the Illinois Settlement Legislation. See Note 3 - Regulatory Matters and Note 10 - Derivative Financial Information for additional information.

[21] To fulfill a requirement of the Illinois Settlement Legislation, ComEd entered into a five-year financial swap with Generation.

[22] The voluntary employee beneficiary association trusts covering active employees are included in corporate operations and are funded by the operating segments. A prepayment to the active welfare plans has accumulated due to actuarially determined contribution rates, which are the basis for PECO's contributions to the plans, being higher than actual claim expense incurred by the plans over time.

[23] PECO 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. A portion of such services is capitalized.

[24] PECO provides energy to Generation for Generation's own use.

[25] PECO obtained all of its electric supply from Generation through 2010 under a PPA. Beginning January 1, 2011, PECO purchases electric supply from Generation under contracts executed through its competitive procurement process. In addition, PECO has five-year and ten-year agreements with Generation to purchase non-solar and solar AECs, respectively. See Note 3 - Regulatory Matters for additional information on AECs.

[26] PECO has a long-term receivable from Generation as a result of the nuclear decommissioning contractual construct, whereby, to the extent the assets associated with decommissioning are greater than the applicable ARO at the end of decommissioning, such amounts are due back to PECO for payment to PECO's customers.

[27] BGE 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. A portion of such services is capitalized.

[28] BGE receives a variety of corporate support services from Exelon Corporate, including payroll and benefits services.

[29] BGE provides energy to Generation for Generation's own use.

[30] BGE procures a portion of its electricity and gas supply requirements from Generation under its MDPSC-approved market-based SOS and gas commodity programs. See Note 3 - Regulatory Matters for additional information