Face (par) amount of debt instrument at time of issuance.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 835

-SubTopic 30

-Section 45

-Paragraph 2

-URI http://asc.fasb.org/extlink&oid=6451184&loc=d3e28551-108399

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 835

-SubTopic 30

-Section 55

-Paragraph 8

-URI http://asc.fasb.org/extlink&oid=34725769&loc=d3e28878-108400

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- Definition

Contractual interest rate for funds borrowed, under the debt agreement.

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Maximum contractual interest rate for funds borrowed, under the debt agreement.

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Minimum contractual interest rate for funds borrowed, under the debt agreement.

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- Definition

Carrying amount of long-term debt, net of unamortized discount or premium, including current and noncurrent amounts. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.5-02.22)

-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 942

-SubTopic 210

-Section S99

-Paragraph 1

-Subparagraph (SX 210.9-03.16)

-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 944

-SubTopic 210

-Section S99

-Paragraph 1

-Subparagraph (SX 210.7-03.16)

-URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910

Reference 4: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 20, 22

-Article 5

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Debt and Credit Agreements - Schedule of Issuance of Long-Term Debt (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014	Apr. 29, 2015	Apr. 01, 2015
Debt Instrument [Line Items]
Long-term Debt	$ 131us-gaap_LongTermDebt
Exelon Generation Co L L C [Member]
Debt Instrument [Line Items]
Interest Rate	3.71%
Exelon Generation Co L L C [Member] \| ExgenRenewablesI425June62021[Member]
Debt Instrument [Line Items]
Debt Instrument, Face Amount		300
Exelon Generation Co L L C [Member] \| Energy Efficiency Project Financing [Member]
Debt Instrument [Line Items]
Debt Instrument, Face Amount	42
Exelon Generation Co L L C [Member] \| AVSR [Member]
Debt Instrument [Line Items]
Debt Instrument, Face Amount	14		18	7
Exelon Generation Co L L C [Member] \| Continental Wind 6000 February 28, 2033 [Member]
Debt Instrument [Line Items]
Interest Rate		6.00%
Exelon Generation Co L L C [Member] \| Senior Notes [Member] \| SeniorNotesJan152020 [Member]
Debt Instrument [Line Items]
Interest Rate	2.95%
Debt Instrument, Face Amount	750
Debt Instrument, Interest Rate, Stated Percentage Rate Range, Minimum	2.293%
Debt Instrument, Interest Rate, Stated Percentage Rate Range, Maximum	2.559%
Commonwealth Edison Co [Member] \| FirstMortgageBondSeries118March12045 [Member]
Debt Instrument [Line Items]
Debt Instrument, Face Amount	400
Commonwealth Edison Co [Member] \| First Mortgage Bonds [Member] \| FirstMortgageBondSeries115January152019 [Member]
Debt Instrument [Line Items]
Interest Rate		2.15%
Debt Instrument, Face Amount		300
Commonwealth Edison Co [Member] \| First Mortgage Bonds [Member] \| FirstMortgageBondSeries116January152044 [Member]
Debt Instrument [Line Items]
Interest Rate		4.70%
Debt Instrument, Face Amount		$ 350