Variable Interest Entities - Carrying Amounts and Classification of Consolidated VIE Assets and Liabilities (Details) - USD ($) $ in Millions		Dec. 31, 2015		Dec. 31, 2014
Variable Interest Entity [Line Items]
Current assets	[1]	$ 909	[2]	$ 1,275
Noncurrent assets	[1]	8,009	[2]	7,573
Total assets	[1]	8,918	[2]	8,848
Current liabilities	[1]	473	[2]	611
Noncurrent liabilities	[1]	2,927	[2]	2,728
Total liabilities	[1]	3,400	[2]	3,339
Assets	[3]	95,384		86,416
Liabilities	[3]	68,062		62,283
Exelon Generation Co L L C [Member]
Variable Interest Entity [Line Items]
Current assets		881	[2]	1,247
Noncurrent assets		8,004	[2]	7,560
Total assets		8,885	[2]	8,807
Current liabilities		387	[2]	526
Noncurrent liabilities		2,884	[2]	2,597
Total liabilities		3,271	[2]	3,123
Assets	[4]	46,529		44,951
Liabilities	[4]	33,559		30,900
Baltimore Gas and Electric Company [Member]
Variable Interest Entity [Line Items]
Current assets		23		21
Noncurrent assets		3		3
Total assets		26		24
Current liabilities		81		77
Noncurrent liabilities		41		120
Total liabilities		122		197
Assets	[5]	8,295		8,056
Liabilities	[5]	$ 5,418		$ 5,303

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

[2] {F|ahBzfndlYmZpbGluZ3MtaHJkcmoLEgZYTUxEb2MiXlhCUkxEb2NHZW5JbmZvOmJiZTkxZGVlYTU0NDQzYzU5MmI5ODA2YTIzODFjMGRkfFRleHRTZWxlY3Rpb246MjU1NjY5QzIzOUJDQTEyODQyNjUxMjI1RThCM0I0ODAM}

[3] Exelon’s consolidated assets include $8,268 million and $8,159 million at December 31, 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 $3,264 million and $2,728 million at December 31, 2015 and December 31, 2014, respectively, of certain VIEs for which the VIE creditors do not have recourse to Exelon. See Note 2–Variable Interest Entities.

[4] Generation’s consolidated assets include $8,235 million and $8,118 million at December 31, 2015 and 2014, respectively, of certain VIEs that can only be used to settle the liabilities of the VIE. Generation’s consolidated liabilities include $3,135 million and $2,512 million at December 31, 2015 and 2014, respectively, of certain VIEs for which the VIE creditors do not have recourse to Generation. See Note 2–Variable Interest Entities.

[5] BGE’s consolidated assets include $26 million and $24 million at December 31, 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 $122 million and $197 million at December 31, 2015 and December 31, 2014, respectively, of BGE’s consolidated VIE for which the VIE creditors do not have recourse to BGE. See Note 2 - Variable Interest Entities.