Variable Interest Entities - Carrying Amounts and Classification of Consolidated VIE Assets and Liabilities (Details) - USD ($) $ in Millions		Sep. 30, 2016		Dec. 31, 2015
Variable Interest Entity [Line Items]
Current Assets	[2]	$ 914	[1]	$ 909
Non Current Assets	[2]	8,235	[1]	8,009
Total Assets	[2]	9,149	[1]	8,918
Current Liabilities	[2]	569	[1]	473
Non Current Liabilities	[2]	3,090	[1]	2,927
Total Liabilities	[2]	3,659	[1]	3,400
Assets		114,535		95,384
Total liabilities	[3]	87,049		68,062
Variable Interest Entity, Primary Beneficiary [Member]
Variable Interest Entity [Line Items]
Assets		8,514		8,268
Total liabilities		3,438		3,264
Exelon Generation Co L L C [Member]
Variable Interest Entity [Line Items]
Current Assets		849	[1]	881
Non Current Assets		8,201	[1]	8,004
Total Assets		9,050	[1]	8,885
Current Liabilities		439	[1]	387
Non Current Liabilities		2,979	[1]	2,884
Total Liabilities		3,418	[1]	3,271
Assets		47,568		46,529
Total liabilities	[4]	33,829		33,559
Exelon Generation Co L L C [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Variable Interest Entity [Line Items]
Assets		8,415		8,235
Total liabilities		3,196		3,135
Baltimore Gas and Electric Company [Member]
Variable Interest Entity [Line Items]
Current Assets		44		23
Non Current Assets		3		3
Total Assets		47		26
Current Liabilities		84		81
Non Current Liabilities		0		41
Total Liabilities		84		122
Assets	[5]	8,857		8,295
Total liabilities	[5]	6,100		5,418
Baltimore Gas and Electric Company [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Variable Interest Entity [Line Items]
Assets		47		26
Total liabilities		83		122
Pepco Holdings LLC [Member] | Predecessor [Member]
Variable Interest Entity [Line Items]
Current Assets				12
Non Current Assets				18
Total Assets				30
Current Liabilities				48
Non Current Liabilities				124
Total Liabilities				172
Assets				16,188
Total liabilities				11,592
Pepco Holdings LLC [Member] | Successor [Member]
Variable Interest Entity [Line Items]
Current Assets		20
Non Current Assets		31
Total Assets		51
Current Liabilities		45
Non Current Liabilities		111
Total Liabilities		156
Assets		21,063
Total liabilities		13,176
Pepco Holdings LLC [Member] | Variable Interest Entity, Primary Beneficiary [Member] | Predecessor [Member]
Variable Interest Entity [Line Items]
Assets				30
Total liabilities				172
Pepco Holdings LLC [Member] | Variable Interest Entity, Primary Beneficiary [Member] | Successor [Member]
Variable Interest Entity [Line Items]
Assets		51
Total liabilities		156
Atlantic City Electric Company [Member]
Variable Interest Entity [Line Items]
Current Assets		15		12
Non Current Assets		19		18
Total Assets		34		30
Current Liabilities		40		48
Non Current Liabilities		99		124
Total Liabilities		139		172
Assets		3,507		3,387
Total liabilities		2,442		2,387
Atlantic City Electric Company [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Variable Interest Entity [Line Items]
Assets		34		30
Total liabilities		$ 139		$ 172

[1] .

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

[3] Exelon’s consolidated assets include $8,514 million and $8,268 million at September 30, 2016 and December 31, 2015, respectively, of certain VIEs that can only be used to settle the liabilities of the VIE. Exelon’s consolidated liabilities include $3,438 million and $3,264 million at September 30, 2016 and December 31, 2015, respectively, of certain VIEs for which the VIE creditors do not have recourse to Exelon. See Note 3 - Variable Interest Entities.

[4] Generation’s consolidated assets include $8,415 million and $8,235 million at September 30, 2016 and December 31, 2015, respectively, of certain VIEs that can only be used to settle the liabilities of the VIE. Generation’s consolidated liabilities include $3,196 million and $3,135 million at September 30, 2016 and December 31, 2015, respectively, of certain VIEs for which the VIE creditors do not have recourse to Generation. See Note 3 - Variable Interest Entities.

[5] BGE’s consolidated assets include $47 million and $26 million at September 30, 2016 and December 31, 2015, respectively, of BGE’s consolidated VIE that can only be used to settle the liabilities of the VIE. BGE’s consolidated liabilities include $83 million and $122 million at September 30, 2016 and December 31, 2015, respectively, of BGE’s consolidated VIE for which the VIE creditors do not have recourse to BGE. See Note 3 - Variable Interest Entities.