|
Fair Value of Financial Assets and Liabilities - Fair Value Inputs Assets Quantitative Information (Details) (USD $)
|
9 Months Ended | 12 Months Ended |
|---|---|---|
|
Sep. 30, 2014
|
Dec. 31, 2013
|
|
| Derivatives Fair Value Footnotes [Abstract] | ||
| Cash collateral excluded | $ 231,000,000 | |
|
Fair Value, Inputs, Level 3 [Member]
|
||
| Derivatives Fair Value Footnotes [Abstract] | ||
| Cash collateral excluded | 26,000,000 | |
|
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 3 [Member] | Derivative [Member]
|
||
| Derivatives, Fair Value [Line Items] | ||
| Derivative Asset, Fair Value, Amount Not Offset Against Collateral | 189,000,000 | 488,000,000 |
|
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 3 [Member] | Derivative [Member] | Discounted Cash Flow [Member] | Minimum [Member]
|
||
| Fair Value Inputs [Abstract] | ||
| Forward power price assets | 13,000,000 | 8 |
| Forward gas price assets | 2.54 | 2.98 |
| Volatility percentage | 14.00% | |
|
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 3 [Member] | Derivative [Member] | Discounted Cash Flow [Member] | Maximum [Member]
|
||
| Fair Value Inputs [Abstract] | ||
| Forward power price assets | 194 | 176 |
| Forward gas price assets | 22.15 | 16.63 |
| Volatility percentage | 19.00% | |
|
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 3 [Member] | Derivative [Member] | Option Model Valuation Technique [Member] | Minimum [Member]
|
||
| Fair Value Inputs [Abstract] | ||
| Volatility percentage | 8.00% | 15.00% |
|
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 3 [Member] | Derivative [Member] | Option Model Valuation Technique [Member] | Maximum [Member]
|
||
| Fair Value Inputs [Abstract] | ||
| Volatility percentage | 154.00% | 142.00% |
|
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 3 [Member] | Proprietary Trading [Member]
|
||
| Derivatives, Fair Value [Line Items] | ||
| Derivative Liability, Fair Value, Amount Not Offset Against Collateral | (11,000,000) | (3,000,000) |
|
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 3 [Member] | Proprietary Trading [Member] | Discounted Cash Flow [Member] | Minimum [Member]
|
||
| Fair Value Inputs [Abstract] | ||
| Forward power price assets | 14,000,000 | 10 |
|
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 3 [Member] | Proprietary Trading [Member] | Discounted Cash Flow [Member] | Maximum [Member]
|
||
| Fair Value Inputs [Abstract] | ||
| Forward power price assets | 191 | 176 |
|
Commonwealth Edison Co [Member] | Fair Value, Inputs, Level 3 [Member] | Derivative [Member]
|
||
| Derivatives, Fair Value [Line Items] | ||
| Derivative Liability, Fair Value, Amount Not Offset Against Collateral | 178,000,000 | 193,000,000 |
|
Commonwealth Edison Co [Member] | Fair Value, Inputs, Level 3 [Member] | Derivative [Member] | Discounted Cash Flow [Member] | Minimum [Member]
|
||
| Fair Value Inputs [Abstract] | ||
| Marketability Reserve | 3.50% | 3.50% |
| Forward heat rate | (8.00%) | (8.00%) |
| Renewable factor | 86.00% | 84.00% |
|
Commonwealth Edison Co [Member] | Fair Value, Inputs, Level 3 [Member] | Derivative [Member] | Discounted Cash Flow [Member] | Maximum [Member]
|
||
| Fair Value Inputs [Abstract] | ||
| Marketability Reserve | 8.00% | 8.00% |
| Forward heat rate | (9.00%) | (9.00%) |
| Renewable factor | 126.00% | 128.00% |
|
All Regions excluding New England [Member] | Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 3 [Member] | Derivative [Member] | Discounted Cash Flow [Member] | Maximum [Member]
|
||
| Fair Value Inputs [Abstract] | ||
| Forward power price assets | 146 | 100 |
| Forward gas price assets | 10.62 | 5.7 |
|
All Regions excluding New England [Member] | Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 3 [Member] | Proprietary Trading [Member] | Discounted Cash Flow [Member] | Maximum [Member]
|
||
| Fair Value Inputs [Abstract] | ||
| Forward power price assets | $ 104 |