Variable Interest Entities - Carrying Amounts and Classification of Consolidated VIE Assets and Liabilities (Details) - USD ($) $ in Millions		Sep. 30, 2015	Dec. 31, 2014
Variable Interest Entity [Line Items]
Current Assets	[1]	$ 1,108	$ 1,271
Non Current Assets	[1]	7,736	7,580
Total Assets	[1]	8,844	8,851
Current Liabilities	[1]	494	611
Non Current Liabilities	[1]	2,859	2,730
Total Liabilities	[1]	3,353	3,341
Assets		95,128	86,814
Total liabilities	[2]	67,839	62,681
Variable Interest Entity, Primary Beneficiary [Member]
Variable Interest Entity [Line Items]
Assets		8,190	8,160
Total liabilities		3,242	2,723
Exelon Generation Co L L C [Member]
Variable Interest Entity [Line Items]
Current Assets		1,057	1,242
Non Current Assets		7,728	7,566
Total Assets		8,785	8,808
Current Liabilities		408	526
Non Current Liabilities		2,773	2,600
Total Liabilities		3,181	3,126
Assets	[3]	46,479	45,348
Total liabilities	[3]	33,555	31,297
Exelon Generation Co L L C [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Variable Interest Entity [Line Items]
Assets		8,130	8,119
Total liabilities		3,070	2,507
Baltimore Gas and Electric Company [Member]
Variable Interest Entity [Line Items]
Current Assets		46	21
Non Current Assets		3	3
Total Assets		49	24
Current Liabilities		81	77
Non Current Liabilities		81	120
Total Liabilities		162	197
Assets	[4]	8,134	8,078
Total liabilities	[4]	5,289	5,325
Baltimore Gas and Electric Company [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Variable Interest Entity [Line Items]
Assets		49	24
Total liabilities		$ 162	$ 197

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

[2] Exelon’s consolidated assets include $8,190 million and $8,160 million at September 30, 2015 and December 31, 2014, respectively, of certain VIEs that can only be used to settle the liabilities of the VIE. Exelon’s consolidated liabilities include $3,242 million and $2,723 million at September 30, 2015 and December 31, 2014, respectively, of certain VIEs for which the VIE creditors do not have recourse to Exelon. See Note 3 — Variable Interest Entities.

[3] Generation’s consolidated assets include $8,130 million and $8,119 million at September 30, 2015 and December 31, 2014, respectively, of certain VIEs that can only be used to settle the liabilities of the VIE. Generation’s consolidated liabilities include $3,070 million and $2,507 million at September 30, 2015 and December 31, 2014, respectively, of certain VIEs for which the VIE creditors do not have recourse to Generation. See Note 3 — Variable Interest Entities.

[4] BGE’s consolidated assets include $49 million and $24 million at September 30, 2015 and December 31, 2014, respectively, of BGE’s consolidated VIE that can only be used to settle the liabilities of the VIE. BGE’s consolidated liabilities include $162 million and $197 million at September 30, 2015 and December 31, 2014, respectively, of BGE’s consolidated VIE for which the VIE creditors do not have recourse to BGE. See Note 3 — Variable Interest Entities.