Debt and Credit Agreements - Schedule of Long-term Debt Maturities (Details) (USD $)	Dec. 31, 2014		Jun. 30, 2014	Dec. 31, 2013
Debt Instrument [Line Items]
2015	$ 1,739,000,000
2016	1,269,000,000
2017	2,400,000,000
2018	1,415,000,000
2019	982,000,000
Thereafter	13,599,000,000	[1]
Total	21,404,000,000		131,000,000
Long-term debt to financing trusts	648,000,000			648,000,000
BGE Trust Member [Member]
Debt Instrument [Line Items]
Long-term debt to financing trusts	258,000,000	[2]		258,000,000	[2]
ComEd Financing Three Affiliate [Member]
Debt Instrument [Line Items]
Long-term debt to financing trusts	206,000,000	[2]		206,000,000	[2]
ComEd, PECO and BGE Financing Trusts [Member]
Debt Instrument [Line Items]
Long-term debt to financing trusts	648,000,000	[2]
PECO Financing Trusts [Member]
Debt Instrument [Line Items]
Long-term debt to financing trusts	184,000,000	[2]
Exelon Generation Co L L C [Member]
Debt Instrument [Line Items]
2015	604,000,000
2016	4,000,000
2017	705,000,000
2018	75,000,000
2019	682,000,000
Thereafter	6,064,000,000
Total	8,134,000,000
Long-term debt to financing trusts	943,000,000			1,523,000,000
Commonwealth Edison Co [Member]
Debt Instrument [Line Items]
2015	260,000,000
2016	665,000,000
2017	425,000,000
2018	840,000,000
2019	300,000,000
Thereafter	3,693,000,000	[3]
Total	6,183,000,000
Long-term debt to financing trusts	206,000,000			206,000,000
Commonwealth Edison Co [Member] | ComEd Financing Three Affiliate [Member]
Debt Instrument [Line Items]
Long-term debt to financing trusts	206,000,000	[2]
PECO Energy Co [Member]
Debt Instrument [Line Items]
2015	0
2016	300,000,000
2017	0
2018	500,000,000
2019	0
Thereafter	1,634,000,000	[4]
Total	2,434,000,000
Long-term debt to financing trusts	184,000,000	[5]		184,000,000	[5]
Baltimore Gas and Electric Company [Member]
Debt Instrument [Line Items]
2015	75,000,000
2016	300,000,000
2017	120,000,000
2018	0
2019	0
Thereafter	1,708,000,000	[6]
Total	2,203,000,000
Long-term debt to financing trusts	258,000,000			258,000,000
Baltimore Gas and Electric Company [Member] | BGE Trust Member [Member]
Debt Instrument [Line Items]
Long-term debt to financing trusts	$ 258,000,000	[7]		$ 258,000,000	[7]

[1] Includes $648 million due to ComEd, PECO and BGE financing trusts.

[2] Amounts owed to these financing trusts are recorded as Long-term debt to financing trusts within Exelon’s Consolidated Balance Sheets.

[3] Includes $206 million due to ComEd financing trust.

[4] Includes $184 million due to PECO financing trusts.

[5] Amounts owed to this financing trust are recorded as Long-term debt to financing trusts within PECO’s Consolidated Balance Sheets.

[6] ncludes $258 million due to BGE financing trust.

[7] Amount owed to this financing trust is recorded as Long-term debt to financing trust within BGE’s Consolidated Balance Sheets.