Property, Plant and Equipment - Annual Depreciation Provisions as Percentage of Average Service Life (Details)	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Electric Transmission and Distribution Equipment [Member]
Property, Plant and Equipment [Line Items]
Annual depreciation rate	2.93%	2.91%	2.76%
Electric Generation Equipment [Member]
Property, Plant and Equipment [Line Items]
Annual depreciation rate	3.50%	3.35%	3.15%
Gas Distribution Equipment [Member]
Property, Plant and Equipment [Line Items]
Annual depreciation rate	2.13%	2.06%	2.03%
Common Electric And Gas T And D Equipment [Member]
Property, Plant and Equipment [Line Items]
Annual depreciation rate	7.32%	7.53%	7.61%
PECO Energy Co [Member] | Electric Transmission and Distribution Equipment [Member]
Property, Plant and Equipment [Line Items]
Annual depreciation rate	2.55%	2.73%	2.51%
PECO Energy Co [Member] | Gas Distribution Equipment [Member]
Property, Plant and Equipment [Line Items]
Annual depreciation rate	1.84%	1.79%	1.77%
PECO Energy Co [Member] | Common Electric And Gas T And D Equipment [Member]
Property, Plant and Equipment [Line Items]
Annual depreciation rate	5.16%	6.65%	7.54%
Baltimore Gas and Electric Company [Member] | Electric Transmission and Distribution Equipment [Member]
Property, Plant and Equipment [Line Items]
Annual depreciation rate	2.96%	2.91%	2.92%
Baltimore Gas and Electric Company [Member] | Gas Distribution Equipment [Member]
Property, Plant and Equipment [Line Items]
Annual depreciation rate	2.47%	2.36%	2.33%
Baltimore Gas and Electric Company [Member] | Common Electric And Gas T And D Equipment [Member]
Property, Plant and Equipment [Line Items]
Annual depreciation rate	9.49%	8.45%	7.68%