Income Taxes - Schedule of Carryforwards and Corresponding Valuation Allowances (Details) $ in Millions	Dec. 31, 2015 USD ($)
Internal Revenue Service (IRS) [Member] | General Business Tax Credit Carryforward [Member]
Operating Loss Carryforwards [Line Items]
Tax Credit Carryforward, Amount	$ 416	[1]
Internal Revenue Service (IRS) [Member] | General Business Tax Credit Carryforward [Member] | Exelon Generation Co L L C [Member]
Operating Loss Carryforwards [Line Items]
Tax Credit Carryforward, Amount	415	[1]
Internal Revenue Service (IRS) [Member] | General Business Tax Credit Carryforward [Member] | Commonwealth Edison Co [Member]
Operating Loss Carryforwards [Line Items]
Tax Credit Carryforward, Amount	0	[1]
Internal Revenue Service (IRS) [Member] | General Business Tax Credit Carryforward [Member] | PECO Energy Co [Member]
Operating Loss Carryforwards [Line Items]
Tax Credit Carryforward, Amount	0	[1]
Internal Revenue Service (IRS) [Member] | General Business Tax Credit Carryforward [Member] | Baltimore Gas and Electric Company [Member]
Operating Loss Carryforwards [Line Items]
Tax Credit Carryforward, Amount	0	[1]
State and Local Jurisdiction [Member]
Operating Loss Carryforwards [Line Items]
Federal general business credits carryforward	2,086	[2]
State net operating losses and other credit carryforwards	117
Valuation allowance on state tax attributes	13
State and Local Jurisdiction [Member] | Exelon Generation Co L L C [Member]
Operating Loss Carryforwards [Line Items]
Federal general business credits carryforward	1,259	[3]
State net operating losses and other credit carryforwards	66
Valuation allowance on state tax attributes	11
State and Local Jurisdiction [Member] | Commonwealth Edison Co [Member]
Operating Loss Carryforwards [Line Items]
Federal general business credits carryforward	0
State net operating losses and other credit carryforwards	0
Valuation allowance on state tax attributes	0
State and Local Jurisdiction [Member] | PECO Energy Co [Member]
Operating Loss Carryforwards [Line Items]
Federal general business credits carryforward	0
State net operating losses and other credit carryforwards	0
Valuation allowance on state tax attributes	0
State and Local Jurisdiction [Member] | Baltimore Gas and Electric Company [Member]
Operating Loss Carryforwards [Line Items]
Federal general business credits carryforward	618
State net operating losses and other credit carryforwards	34
Valuation allowance on state tax attributes	$ 1

[1] Exelon’s and Generation's state net operating losses and other carryforwards, which are presented on a post-apportioned basis, will expire beginning in 201

[2] 6

[3] 6