Debt and Credit Agreements - Summary of Bank Commitments, Credit Facility Borrowings and Available Capacity (Details) - USD ($)		Dec. 31, 2015		Dec. 31, 2014	May. 30, 2014	[4],[5]	Mar. 28, 2014	[4],[5]
Short-term Debt [Line Items]
Facility draws		$ 0
Outstanding letters of credit	[1]	1,478,000,000
Actual available capacity		6,947,000,000
To Support Additional Commercial Paper	[2]	6,341,000,000
Exelon Corporate [Member]
Short-term Debt [Line Items]
Facility draws		0
Outstanding letters of credit	[1]	26,000,000
Actual available capacity		474,000,000
To Support Additional Commercial Paper	[2]	474,000,000
Exelon Generation Co L L C [Member]
Short-term Debt [Line Items]
Facility draws		0
Outstanding letters of credit	[1]	1,449,000,000
Actual available capacity		4,276,000,000
To Support Additional Commercial Paper	[2]	4,174,000,000
Credit facility agreements with minority and community banks		50,000,000
Letters of credit		7,000,000
Bilateral letters of credit		275,000,000		$ 200,000,000
Commonwealth Edison Co [Member]
Short-term Debt [Line Items]
Facility draws		0
Outstanding letters of credit	[1]	2,000,000
Actual available capacity		998,000,000
To Support Additional Commercial Paper	[2]	704,000,000
Credit facility agreements with minority and community banks		34,000,000
Letters of credit		14,000,000
PECO Energy Co [Member]
Short-term Debt [Line Items]
Facility draws		0
Outstanding letters of credit	[1]	1,000,000
Actual available capacity		599,000,000
To Support Additional Commercial Paper	[2]	599,000,000
Credit facility agreements with minority and community banks		34,000,000
Letters of credit		21,000,000
Baltimore Gas and Electric Company [Member]
Short-term Debt [Line Items]
Facility draws		0
Outstanding letters of credit	[1]	0
Actual available capacity		600,000,000
To Support Additional Commercial Paper	[2]	390,000,000
Credit facility agreements with minority and community banks		5,000,000
Letters of credit		2,000,000
Revolving Credit Facility [Member]
Short-term Debt [Line Items]
Maximum Program Size	[3]	8,425,000,000
Revolving Credit Facility [Member] | Exelon Corporate [Member]
Short-term Debt [Line Items]
Maximum Program Size		500,000,000	[3]		$ 500,000,000
Revolving Credit Facility [Member] | Exelon Generation Co L L C [Member]
Short-term Debt [Line Items]
Maximum Program Size	[3]	5,725,000,000
Revolving Credit Facility [Member] | Commonwealth Edison Co [Member]
Short-term Debt [Line Items]
Maximum Program Size		1,000,000,000	[3]				$ 1,000,000,000
Revolving Credit Facility [Member] | PECO Energy Co [Member]
Short-term Debt [Line Items]
Maximum Program Size		600,000,000	[3]		$ 600,000,000
Revolving Credit Facility [Member] | Baltimore Gas and Electric Company [Member]
Short-term Debt [Line Items]
Maximum Program Size	[3]	$ 600,000,000

[1] Excludes nonrecourse debt letters of credit, see discussion below on Continental Wind.

[2] Excludes $275 million bilateral credit facilities that do not back Generation’s commercial paper program

[3] Excludes additional credit facilities for Generation, ComEd, PECO and BGE with aggregate commitments of $50 million, $34 million, $34 million and $5 million, respectively, arranged with minority and community banks located primarily within ComEd’s, PECO’s and BGE’s service territories. The agreements for these facilities expired on October 16, 2015 and were renewed at the same amount through October 14, 2016. These facilities are solely utilized to issue letters of credit. As of December 31, 2015, letters of credit issued under these facilities totaled $7 million, $14 million, $21 million and $2 million for Generation, ComEd, PECO and BGE, respectively.

[4] Excludes additional credit facilities for Generation, ComEd, PECO and BGE with aggregate commitments of $50 million, $34 million, $34 million and $5 million, respectively, arranged with minority and community banks located primarily within ComEd’s, PECO’s and BGE’s service territories. The agreements for these facilities expired on October 16, 2015 and were renewed at the same amount through October 14, 2016. These facilities are solely utilized to issue letters of credit. As of December 31, 2015, letters of credit issued under these facilities totaled $7 million, $14 million, $21 million and $2 million for Generation, ComEd, PECO and BGE, respectively.

[5] Reflects aggregate bank commitments under the revolving and bilateral credit agreements (with the exception of $275 million and $200 million bilateral agreements for Generation as of December 31, 2015 and 2014, respectively) that backstop the commercial paper program. See discussion and Credit Facilities table below for items affecting effective program size.