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Fair Value of Financial Assets and Liabilities (Details) (USD $)
In Millions
 3 Months Ended 6 Months Ended 3 Months Ended 6 Months Ended 3 Months Ended 6 Months Ended 3 Months Ended 6 Months Ended 3 Months Ended 6 Months Ended 3 Months Ended 6 Months Ended 3 Months Ended 6 Months Ended 3 Months Ended 6 Months Ended 3 Months Ended 6 Months Ended 6 Months Ended 3 Months Ended 6 Months Ended 3 Months Ended 6 Months Ended 3 Months Ended 6 Months Ended 3 Months Ended 6 Months Ended 3 Months Ended 6 Months Ended 3 Months Ended 6 Months Ended 3 Months Ended 6 Months Ended 3 Months Ended 6 Months Ended
Jun. 30, 2011
Jun. 30, 2010
Jun. 30, 2011
Jun. 30, 2010
Dec. 31, 2010
Jun. 30, 2011
Exelon Generation Co L L C [Member]
Jun. 30, 2010
Exelon Generation Co L L C [Member]
Jun. 30, 2011
Exelon Generation Co L L C [Member]
Jun. 30, 2010
Exelon Generation Co L L C [Member]
Dec. 31, 2010
Exelon Generation Co L L C [Member]
Jun. 30, 2011
Exelon Generation Co L L C [Member]
Fair Value Inputs Level 1 [Member]
Dec. 31, 2010
Exelon Generation Co L L C [Member]
Fair Value Inputs Level 1 [Member]
Jun. 30, 2011
Exelon Generation Co L L C [Member]
Fair Value Inputs Level 1 [Member]
Nuclear Decommissioning Trust Fund Investments [Member]
Dec. 31, 2010
Exelon Generation Co L L C [Member]
Fair Value Inputs Level 1 [Member]
Nuclear Decommissioning Trust Fund Investments [Member]
Jun. 30, 2011
Exelon Generation Co L L C [Member]
Fair Value Inputs Level 1 [Member]
Pledged Assets For Zion Station Decommissioning [Member]
Dec. 31, 2010
Exelon Generation Co L L C [Member]
Fair Value Inputs Level 1 [Member]
Pledged Assets For Zion Station Decommissioning [Member]
Jun. 30, 2011
Exelon Generation Co L L C [Member]
Fair Value Inputs Level 1 [Member]
Rabbi Trust Investments [Member]
Dec. 31, 2010
Exelon Generation Co L L C [Member]
Fair Value Inputs Level 1 [Member]
Rabbi Trust Investments [Member]
Jun. 30, 2011
Exelon Generation Co L L C [Member]
Fair Value Inputs Level 1 [Member]
Derivative Financial Instruments Assets [Member]
Dec. 31, 2010
Exelon Generation Co L L C [Member]
Fair Value Inputs Level 1 [Member]
Derivative Financial Instruments Assets [Member]
Jun. 30, 2011
Exelon Generation Co L L C [Member]
Fair Value Inputs Level 1 [Member]
Derivative Financial Instruments Liabilities [Member]
Dec. 31, 2010
Exelon Generation Co L L C [Member]
Fair Value Inputs Level 1 [Member]
Derivative Financial Instruments Liabilities [Member]
Jun. 30, 2011
Exelon Generation Co L L C [Member]
Fair Value Inputs Level 2 [Member]
Dec. 31, 2010
Exelon Generation Co L L C [Member]
Fair Value Inputs Level 2 [Member]
Jun. 30, 2011
Exelon Generation Co L L C [Member]
Fair Value Inputs Level 2 [Member]
Nuclear Decommissioning Trust Fund Investments [Member]
Dec. 31, 2010
Exelon Generation Co L L C [Member]
Fair Value Inputs Level 2 [Member]
Nuclear Decommissioning Trust Fund Investments [Member]
Jun. 30, 2011
Exelon Generation Co L L C [Member]
Fair Value Inputs Level 2 [Member]
Pledged Assets For Zion Station Decommissioning [Member]
Dec. 31, 2010
Exelon Generation Co L L C [Member]
Fair Value Inputs Level 2 [Member]
Pledged Assets For Zion Station Decommissioning [Member]
Jun. 30, 2011
Exelon Generation Co L L C [Member]
Fair Value Inputs Level 2 [Member]
Rabbi Trust Investments [Member]
Dec. 31, 2010
Exelon Generation Co L L C [Member]
Fair Value Inputs Level 2 [Member]
Rabbi Trust Investments [Member]
Jun. 30, 2011
Exelon Generation Co L L C [Member]
Fair Value Inputs Level 2 [Member]
Derivative Financial Instruments Assets [Member]
Dec. 31, 2010
Exelon Generation Co L L C [Member]
Fair Value Inputs Level 2 [Member]
Derivative Financial Instruments Assets [Member]
Jun. 30, 2011
Exelon Generation Co L L C [Member]
Fair Value Inputs Level 2 [Member]
Derivative Financial Instruments Liabilities [Member]
Dec. 31, 2010
Exelon Generation Co L L C [Member]
Fair Value Inputs Level 2 [Member]
Derivative Financial Instruments Liabilities [Member]
Jun. 30, 2011
Exelon Generation Co L L C [Member]
Fair Value Inputs Level 3 [Member]
Dec. 31, 2010
Exelon Generation Co L L C [Member]
Fair Value Inputs Level 3 [Member]
Jun. 30, 2011
Exelon Generation Co L L C [Member]
Fair Value Inputs Level 3 [Member]
Nuclear Decommissioning Trust Fund Investments [Member]
Dec. 31, 2010
Exelon Generation Co L L C [Member]
Fair Value Inputs Level 3 [Member]
Nuclear Decommissioning Trust Fund Investments [Member]
Jun. 30, 2011
Exelon Generation Co L L C [Member]
Fair Value Inputs Level 3 [Member]
Pledged Assets For Zion Station Decommissioning [Member]
Dec. 31, 2010
Exelon Generation Co L L C [Member]
Fair Value Inputs Level 3 [Member]
Pledged Assets For Zion Station Decommissioning [Member]
Jun. 30, 2011
Exelon Generation Co L L C [Member]
Fair Value Inputs Level 3 [Member]
Rabbi Trust Investments [Member]
Dec. 31, 2010
Exelon Generation Co L L C [Member]
Fair Value Inputs Level 3 [Member]
Rabbi Trust Investments [Member]
Jun. 30, 2011
Exelon Generation Co L L C [Member]
Fair Value Inputs Level 3 [Member]
Derivative Financial Instruments Assets [Member]
Dec. 31, 2010
Exelon Generation Co L L C [Member]
Fair Value Inputs Level 3 [Member]
Derivative Financial Instruments Assets [Member]
Jun. 30, 2011
Exelon Generation Co L L C [Member]
Fair Value Inputs Level 3 [Member]
Derivative Financial Instruments Liabilities [Member]
Dec. 31, 2010
Exelon Generation Co L L C [Member]
Fair Value Inputs Level 3 [Member]
Derivative Financial Instruments Liabilities [Member]
Jun. 30, 2011
Exelon Generation Co L L C [Member]
Operating Revenue [Member]
Jun. 30, 2010
Exelon Generation Co L L C [Member]
Operating Revenue [Member]
Jun. 30, 2011
Exelon Generation Co L L C [Member]
Operating Revenue [Member]
Jun. 30, 2010
Exelon Generation Co L L C [Member]
Operating Revenue [Member]
Jun. 30, 2011
Exelon Generation Co L L C [Member]
Purchased Power [Member]
Jun. 30, 2010
Exelon Generation Co L L C [Member]
Purchased Power [Member]
Jun. 30, 2011
Exelon Generation Co L L C [Member]
Purchased Power [Member]
Jun. 30, 2010
Exelon Generation Co L L C [Member]
Purchased Power [Member]
Jun. 30, 2011
Exelon Generation Co L L C [Member]
Fuel [Member]
Jun. 30, 2010
Exelon Generation Co L L C [Member]
Fuel [Member]
Jun. 30, 2011
Exelon Generation Co L L C [Member]
Fuel [Member]
Jun. 30, 2010
Exelon Generation Co L L C [Member]
Fuel [Member]
Jun. 30, 2011
Exelon Generation Co L L C [Member]
Nuclear Decommissioning Trust Fund Investments [Member]
Dec. 31, 2010
Exelon Generation Co L L C [Member]
Nuclear Decommissioning Trust Fund Investments [Member]
Jun. 30, 2011
Exelon Generation Co L L C [Member]
Pledged Assets For Zion Station Decommissioning [Member]
Dec. 31, 2010
Exelon Generation Co L L C [Member]
Pledged Assets For Zion Station Decommissioning [Member]
Jun. 30, 2011
Exelon Generation Co L L C [Member]
Rabbi Trust Investments [Member]
Dec. 31, 2010
Exelon Generation Co L L C [Member]
Rabbi Trust Investments [Member]
Jun. 30, 2011
Exelon Generation Co L L C [Member]
Derivative Financial Instruments Assets [Member]
Dec. 31, 2010
Exelon Generation Co L L C [Member]
Derivative Financial Instruments Assets [Member]
Jun. 30, 2011
Exelon Generation Co L L C [Member]
Derivative Financial Instruments Liabilities [Member]
Dec. 31, 2010
Exelon Generation Co L L C [Member]
Derivative Financial Instruments Liabilities [Member]
Jun. 30, 2010
Exelon Generation Co L L C [Member]
Nuclear Decommissioning Trust Fund Investment Level Three Asset [Member]
Jun. 30, 2010
Exelon Generation Co L L C [Member]
Nuclear Decommissioning Trust Fund Investment Level Three Asset [Member]
Dec. 31, 2010
Exelon Generation Co L L C [Member]
Nuclear Decommissioning Trust Fund Investment Level Three Asset [Member]
Jun. 30, 2011
Exelon Generation Co L L C [Member]
Pledged Assets For Zion Station Decommissioning [Member]
Jun. 30, 2011
Exelon Generation Co L L C [Member]
Pledged Assets For Zion Station Decommissioning [Member]
Jun. 30, 2011
Exelon Generation Co L L C [Member]
Derivative [Member]
Jun. 30, 2010
Exelon Generation Co L L C [Member]
Derivative [Member]
Jun. 30, 2011
Exelon Generation Co L L C [Member]
Derivative [Member]
Jun. 30, 2010
Exelon Generation Co L L C [Member]
Derivative [Member]
Jun. 30, 2011
Exelon Generation Co L L C [Member]
Carrying Reported Amount Fair Value Disclosure [Member]
Dec. 31, 2010
Exelon Generation Co L L C [Member]
Carrying Reported Amount Fair Value Disclosure [Member]
Jun. 30, 2011
Exelon Generation Co L L C [Member]
Estimate Of Fair Value Fair Value Disclosure [Member]
Dec. 31, 2010
Exelon Generation Co L L C [Member]
Estimate Of Fair Value Fair Value Disclosure [Member]
Jun. 30, 2011
Commonwealth Edison Co [Member]
Dec. 31, 2010
Commonwealth Edison Co [Member]
Jun. 30, 2011
Commonwealth Edison Co [Member]
Fair Value Inputs Level 1 [Member]
Dec. 31, 2010
Commonwealth Edison Co [Member]
Fair Value Inputs Level 1 [Member]
Jun. 30, 2011
Commonwealth Edison Co [Member]
Fair Value Inputs Level 1 [Member]
Rabbi Trust Investments [Member]
Dec. 31, 2010
Commonwealth Edison Co [Member]
Fair Value Inputs Level 1 [Member]
Rabbi Trust Investments [Member]
Dec. 31, 2010
Commonwealth Edison Co [Member]
Fair Value Inputs Level 1 [Member]
Derivative Financial Instruments Assets [Member]
Jun. 30, 2011
Commonwealth Edison Co [Member]
Fair Value Inputs Level 1 [Member]
Derivative Financial Instruments Liabilities [Member]
Dec. 31, 2010
Commonwealth Edison Co [Member]
Fair Value Inputs Level 1 [Member]
Derivative Financial Instruments Liabilities [Member]
Jun. 30, 2011
Commonwealth Edison Co [Member]
Fair Value Inputs Level 2 [Member]
Dec. 31, 2010
Commonwealth Edison Co [Member]
Fair Value Inputs Level 2 [Member]
Jun. 30, 2011
Commonwealth Edison Co [Member]
Fair Value Inputs Level 2 [Member]
Rabbi Trust Investments [Member]
Dec. 31, 2010
Commonwealth Edison Co [Member]
Fair Value Inputs Level 2 [Member]
Rabbi Trust Investments [Member]
Dec. 31, 2010
Commonwealth Edison Co [Member]
Fair Value Inputs Level 2 [Member]
Derivative Financial Instruments Assets [Member]
Jun. 30, 2011
Commonwealth Edison Co [Member]
Fair Value Inputs Level 2 [Member]
Derivative Financial Instruments Liabilities [Member]
Dec. 31, 2010
Commonwealth Edison Co [Member]
Fair Value Inputs Level 2 [Member]
Derivative Financial Instruments Liabilities [Member]
Jun. 30, 2011
Commonwealth Edison Co [Member]
Fair Value Inputs Level 3 [Member]
Dec. 31, 2010
Commonwealth Edison Co [Member]
Fair Value Inputs Level 3 [Member]
Jun. 30, 2011
Commonwealth Edison Co [Member]
Fair Value Inputs Level 3 [Member]
Rabbi Trust Investments [Member]
Dec. 31, 2010
Commonwealth Edison Co [Member]
Fair Value Inputs Level 3 [Member]
Rabbi Trust Investments [Member]
Dec. 31, 2010
Commonwealth Edison Co [Member]
Fair Value Inputs Level 3 [Member]
Derivative Financial Instruments Assets [Member]
Jun. 30, 2011
Commonwealth Edison Co [Member]
Fair Value Inputs Level 3 [Member]
Derivative Financial Instruments Liabilities [Member]
Dec. 31, 2010
Commonwealth Edison Co [Member]
Fair Value Inputs Level 3 [Member]
Derivative Financial Instruments Liabilities [Member]
Jun. 30, 2011
Commonwealth Edison Co [Member]
Rabbi Trust Investments [Member]
Dec. 31, 2010
Commonwealth Edison Co [Member]
Rabbi Trust Investments [Member]
Dec. 31, 2010
Commonwealth Edison Co [Member]
Derivative Financial Instruments Assets [Member]
Jun. 30, 2011
Commonwealth Edison Co [Member]
Derivative Financial Instruments Liabilities [Member]
Dec. 31, 2010
Commonwealth Edison Co [Member]
Derivative Financial Instruments Liabilities [Member]
Jun. 30, 2011
Commonwealth Edison Co [Member]
Derivative [Member]
Jun. 30, 2010
Commonwealth Edison Co [Member]
Derivative [Member]
Jun. 30, 2011
Commonwealth Edison Co [Member]
Derivative [Member]
Jun. 30, 2010
Commonwealth Edison Co [Member]
Derivative [Member]
Jun. 30, 2011
Commonwealth Edison Co [Member]
Carrying Reported Amount Fair Value Disclosure [Member]
Dec. 31, 2010
Commonwealth Edison Co [Member]
Carrying Reported Amount Fair Value Disclosure [Member]
Jun. 30, 2011
Commonwealth Edison Co [Member]
Estimate Of Fair Value Fair Value Disclosure [Member]
Dec. 31, 2010
Commonwealth Edison Co [Member]
Estimate Of Fair Value Fair Value Disclosure [Member]
Jun. 30, 2010
PECO Energy Co [Member]
Jun. 30, 2011
PECO Energy Co [Member]
Dec. 31, 2010
PECO Energy Co [Member]
Jun. 30, 2011
PECO Energy Co [Member]
Fair Value Inputs Level 1 [Member]
Dec. 31, 2010
PECO Energy Co [Member]
Fair Value Inputs Level 1 [Member]
Jun. 30, 2011
PECO Energy Co [Member]
Fair Value Inputs Level 1 [Member]
Rabbi Trust Investments [Member]
Dec. 31, 2010
PECO Energy Co [Member]
Fair Value Inputs Level 1 [Member]
Rabbi Trust Investments [Member]
Jun. 30, 2011
PECO Energy Co [Member]
Fair Value Inputs Level 1 [Member]
Derivative Financial Instruments Liabilities [Member]
Dec. 31, 2010
PECO Energy Co [Member]
Fair Value Inputs Level 1 [Member]
Derivative Financial Instruments Liabilities [Member]
Jun. 30, 2011
PECO Energy Co [Member]
Fair Value Inputs Level 2 [Member]
Dec. 31, 2010
PECO Energy Co [Member]
Fair Value Inputs Level 2 [Member]
Jun. 30, 2011
PECO Energy Co [Member]
Fair Value Inputs Level 2 [Member]
Rabbi Trust Investments [Member]
Dec. 31, 2010
PECO Energy Co [Member]
Fair Value Inputs Level 2 [Member]
Rabbi Trust Investments [Member]
Jun. 30, 2011
PECO Energy Co [Member]
Fair Value Inputs Level 2 [Member]
Derivative Financial Instruments Liabilities [Member]
Dec. 31, 2010
PECO Energy Co [Member]
Fair Value Inputs Level 2 [Member]
Derivative Financial Instruments Liabilities [Member]
Jun. 30, 2011
PECO Energy Co [Member]
Fair Value Inputs Level 3 [Member]
Dec. 31, 2010
PECO Energy Co [Member]
Fair Value Inputs Level 3 [Member]
Jun. 30, 2011
PECO Energy Co [Member]
Fair Value Inputs Level 3 [Member]
Rabbi Trust Investments [Member]
Dec. 31, 2010
PECO Energy Co [Member]
Fair Value Inputs Level 3 [Member]
Rabbi Trust Investments [Member]
Jun. 30, 2011
PECO Energy Co [Member]
Fair Value Inputs Level 3 [Member]
Derivative Financial Instruments Liabilities [Member]
Dec. 31, 2010
PECO Energy Co [Member]
Fair Value Inputs Level 3 [Member]
Derivative Financial Instruments Liabilities [Member]
Jun. 30, 2011
PECO Energy Co [Member]
Rabbi Trust Investments [Member]
Dec. 31, 2010
PECO Energy Co [Member]
Rabbi Trust Investments [Member]
Jun. 30, 2011
PECO Energy Co [Member]
Derivative Financial Instruments Assets [Member]
Dec. 31, 2010
PECO Energy Co [Member]
Derivative Financial Instruments Assets [Member]
Jun. 30, 2011
PECO Energy Co [Member]
Derivative Financial Instruments Liabilities [Member]
Dec. 31, 2010
PECO Energy Co [Member]
Derivative Financial Instruments Liabilities [Member]
Jun. 30, 2011
PECO Energy Co [Member]
Derivative [Member]
Jun. 30, 2010
PECO Energy Co [Member]
Derivative [Member]
Jun. 30, 2011
PECO Energy Co [Member]
Derivative [Member]
Jun. 30, 2010
PECO Energy Co [Member]
Derivative [Member]
Jun. 30, 2010
PECO Energy Co [Member]
Servicing Liability Level Three Liability [Member]
Jun. 30, 2011
PECO Energy Co [Member]
Carrying Reported Amount Fair Value Disclosure [Member]
Dec. 31, 2010
PECO Energy Co [Member]
Carrying Reported Amount Fair Value Disclosure [Member]
Jun. 30, 2011
PECO Energy Co [Member]
Estimate Of Fair Value Fair Value Disclosure [Member]
Dec. 31, 2010
PECO Energy Co [Member]
Estimate Of Fair Value Fair Value Disclosure [Member]
Jun. 30, 2011
Operating Revenue [Member]
Jun. 30, 2010
Operating Revenue [Member]
Jun. 30, 2011
Operating Revenue [Member]
Jun. 30, 2010
Operating Revenue [Member]
Jun. 30, 2011
Purchased Power [Member]
Jun. 30, 2010
Purchased Power [Member]
Jun. 30, 2011
Purchased Power [Member]
Jun. 30, 2010
Purchased Power [Member]
Jun. 30, 2011
Fuel [Member]
Jun. 30, 2010
Fuel [Member]
Mar. 31, 2010
Fuel [Member]
Jun. 30, 2011
Fuel [Member]
Jun. 30, 2010
Fuel [Member]
Jun. 30, 2011
Other, net [Member]
Jun. 30, 2010
Other, net [Member]
Jun. 30, 2011
Other, net [Member]
Jun. 30, 2010
Other, net [Member]
Jun. 30, 2011
Fair Value Inputs Level 1 [Member]
Dec. 31, 2010
Fair Value Inputs Level 1 [Member]
Jun. 30, 2011
Fair Value Inputs Level 1 [Member]
Nuclear Decommissioning Trust Fund Investments [Member]
Dec. 31, 2010
Fair Value Inputs Level 1 [Member]
Nuclear Decommissioning Trust Fund Investments [Member]
Jun. 30, 2011
Fair Value Inputs Level 1 [Member]
Pledged Assets For Zion Station Decommissioning [Member]
Dec. 31, 2010
Fair Value Inputs Level 1 [Member]
Pledged Assets For Zion Station Decommissioning [Member]
Jun. 30, 2011
Fair Value Inputs Level 1 [Member]
Rabbi Trust Investments [Member]
Dec. 31, 2010
Fair Value Inputs Level 1 [Member]
Rabbi Trust Investments [Member]
Jun. 30, 2011
Fair Value Inputs Level 1 [Member]
Derivative Financial Instruments Assets [Member]
Dec. 31, 2010
Fair Value Inputs Level 1 [Member]
Derivative Financial Instruments Assets [Member]
Jun. 30, 2011
Fair Value Inputs Level 1 [Member]
Derivative Financial Instruments Liabilities [Member]
Dec. 31, 2010
Fair Value Inputs Level 1 [Member]
Derivative Financial Instruments Liabilities [Member]
Jun. 30, 2011
Fair Value Inputs Level 2 [Member]
Dec. 31, 2010
Fair Value Inputs Level 2 [Member]
Jun. 30, 2011
Fair Value Inputs Level 2 [Member]
Nuclear Decommissioning Trust Fund Investments [Member]
Dec. 31, 2010
Fair Value Inputs Level 2 [Member]
Nuclear Decommissioning Trust Fund Investments [Member]
Jun. 30, 2011
Fair Value Inputs Level 2 [Member]
Pledged Assets For Zion Station Decommissioning [Member]
Dec. 31, 2010
Fair Value Inputs Level 2 [Member]
Pledged Assets For Zion Station Decommissioning [Member]
Jun. 30, 2011
Fair Value Inputs Level 2 [Member]
Rabbi Trust Investments [Member]
Dec. 31, 2010
Fair Value Inputs Level 2 [Member]
Rabbi Trust Investments [Member]
Jun. 30, 2011
Fair Value Inputs Level 2 [Member]
Derivative Financial Instruments Assets [Member]
Dec. 31, 2010
Fair Value Inputs Level 2 [Member]
Derivative Financial Instruments Assets [Member]
Jun. 30, 2011
Fair Value Inputs Level 2 [Member]
Derivative Financial Instruments Liabilities [Member]
Dec. 31, 2010
Fair Value Inputs Level 2 [Member]
Derivative Financial Instruments Liabilities [Member]
Jun. 30, 2011
Fair Value Inputs Level 3 [Member]
Dec. 31, 2010
Fair Value Inputs Level 3 [Member]
Jun. 30, 2011
Fair Value Inputs Level 3 [Member]
Nuclear Decommissioning Trust Fund Investments [Member]
Dec. 31, 2010
Fair Value Inputs Level 3 [Member]
Nuclear Decommissioning Trust Fund Investments [Member]
Jun. 30, 2011
Fair Value Inputs Level 3 [Member]
Pledged Assets For Zion Station Decommissioning [Member]
Dec. 31, 2010
Fair Value Inputs Level 3 [Member]
Pledged Assets For Zion Station Decommissioning [Member]
Jun. 30, 2011
Fair Value Inputs Level 3 [Member]
Rabbi Trust Investments [Member]
Dec. 31, 2010
Fair Value Inputs Level 3 [Member]
Rabbi Trust Investments [Member]
Jun. 30, 2011
Fair Value Inputs Level 3 [Member]
Derivative Financial Instruments Assets [Member]
Dec. 31, 2010
Fair Value Inputs Level 3 [Member]
Derivative Financial Instruments Assets [Member]
Jun. 30, 2011
Fair Value Inputs Level 3 [Member]
Derivative Financial Instruments Liabilities [Member]
Dec. 31, 2010
Fair Value Inputs Level 3 [Member]
Derivative Financial Instruments Liabilities [Member]
Jun. 30, 2011
Nuclear Decommissioning Trust Fund Investments [Member]
Dec. 31, 2010
Nuclear Decommissioning Trust Fund Investments [Member]
Jun. 30, 2011
Pledged Assets For Zion Station Decommissioning [Member]
Dec. 31, 2010
Pledged Assets For Zion Station Decommissioning [Member]
Jun. 30, 2011
Pledged Assets For Zion Station Decommissioning [Member]
Jun. 30, 2011
Pledged Assets For Zion Station Decommissioning [Member]
Jun. 30, 2011
Rabbi Trust Investments [Member]
Dec. 31, 2010
Rabbi Trust Investments [Member]
Jun. 30, 2011
Derivative Financial Instruments Assets [Member]
Dec. 31, 2010
Derivative Financial Instruments Assets [Member]
Jun. 30, 2011
Derivative Financial Instruments Liabilities [Member]
Dec. 31, 2010
Derivative Financial Instruments Liabilities [Member]
Jun. 30, 2010
Nuclear Decommissioning Trust Fund Investment Level Three Asset [Member]
Jun. 30, 2010
Nuclear Decommissioning Trust Fund Investment Level Three Asset [Member]
Dec. 31, 2010
Nuclear Decommissioning Trust Fund Investment Level Three Asset [Member]
Jun. 30, 2011
Derivative [Member]
Jun. 30, 2010
Derivative [Member]
Jun. 30, 2011
Derivative [Member]
Jun. 30, 2010
Derivative [Member]
Jun. 30, 2010
Servicing Liability Level Three Liability [Member]
Jun. 30, 2011
Carrying Reported Amount Fair Value Disclosure [Member]
Dec. 31, 2010
Carrying Reported Amount Fair Value Disclosure [Member]
Jun. 30, 2011
Estimate Of Fair Value Fair Value Disclosure [Member]
Dec. 31, 2010
Estimate Of Fair Value Fair Value Disclosure [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis Gain Loss Included In Earnings [Line Items]                                                                                                                                                                                                                                                                                                                                                                                                                                                                            
Total gains (losses) included in income                                                                                             $ 10 $ 15 $ 7 $ 13 $ 10 $ (20) $ 3 $ 36 $ 1 $ 5 $ (2) $ 31                                                                                                                                                                                               $ 10 $ 15 $ 7 $ 13 $ 10 $ (20) $ 3 $ 36 $ 1 $ 5 $ 31 $ (2)   $ 0 $ 0 $ 0 $ 2                                                                                                                        
Change in the unrealized gains (losses) relating to assets and liabilities held                                                                                             17 20 21 23 11 (21) 2 33 2 2 0 22                                                                                                                                                                                               17 20 21 23 11 (21) 2 33 2 2   0 22 0 0 0 0                                                                                                                        
Fair Value Assets And Liabilities Measured On Recurring Basis [Abstract]                                                                                                                                                                                                                                                                                                                                                                                                                                                                            
Cash equivalents 450 [1]   450 [1]   1,473 [1] 74 [1]   74 [1]   419 [1] 74 [1] 419 [1] 3 1                 0 [1] 0 [1] 23 0                 0 [1] 0 [1] 0 0                                         26 1                                           33 [1] 1 [1] 33 [1] 1 [1]           0 [1] 0 [1]           0 [1] 0 [1]                                       298 499 [1] 298 499 [1]         0 0 [1]         0 0 [1]                                                                         450 [1] 1,473 [1] 3 1                 0 [1] 0 [1] 23 0                 0 [1] 0 [1] 0 0                 26 1                                            
Equity securities                         1,425 [2] 1,513 [2] 68 [2] 84 [2]                 0 [2] 0 [2] 0 [2] 0 [2]                 0 [2] 0 [2] 0 [2] 0 [2]                                     1,425 [2] 1,513 [2] 68 [2] 84 [2]                                                                                                                                                                                                                             1,425 [2] 1,513 [2] 68 [2] 84 [2]                 0 [2] 0 [2] 0 [2] 0 [2]                 0 [2] 0 [2] 0 [2] 0 [2]             1,425 [2] 1,513 [2] 68 [2] 84 [2]                                        
Commingled funds                         0 [3] 0 [3] 0 [3] 0 [3]                 2,280 [3] 2,212 [3] 108 [3] 132 [3]                 0 [3] 0 [3] 0 [3] 0 [3]                                     2,280 [3] 2,212 [3] 108 [3] 132 [3]                                                                                                                                                                                                                             0 [4] 0 [4] 0 [4] 0 [4]                 2,280 [4] 2,212 [4] 108 [4] 132 [4]                 0 [4] 0 [4] 0 [4] 0 [4]             2,280 [4] 2,212 [4] 108 [4] 132 [4]                                        
Debt securities issued by the U.S. Treasury and other U.S. government corporations and agencies                         518 504 66 166                 110 96 20 12                 0 0 0 0                                     628 600 86 178                                                                                                                                                                                                                             518 504 66 166                 110 96 20 12                 0 0 0 0             628 600 86 178                                        
Debt securities issued by states of the United States and political subdivisions of the states                         0 0 0 0                 563 451 62 45                 0 0 0 0                                     563 451 62 45                                                                                                                                                                                                                             0 0 0 0                 563 451 62 45                 0 0 0 0             563 451 62 45                                        
Corporate debt securities                         0 0 0 0                 718 619 316 263                 0 0 0 0                                     718 619 316 263                                                                                                                                                                                                                             0 0 0 0                 718 619 316 263                 0 0 0 0             718 619 316 263                                        
Federal agency mortgage-backed securities                         0 0 0 0                 763 804 101 102                 0 0 0 0                                     763 804 101 102                                                                                                                                                                                                                             0 0 0 0                 763 804 101 102                 0 0 0 0             763 804 101 102                                        
Commercial mortgage-backed securities (non-agency)                         0 0 0 0                 128 114 13 14                 0 0 0 0                                     128 114 13 14                                                                                                                                                                                                                             0 0 0 0                 128 114 13 14                 0 0 0 0             128 114 13 14                                        
Residential mortgage-backed securities (non-agency)                         0 0                     6 14                     0 0                                         6 14                                                                                                                                                                                                                                 0 0                     6 14                     0 0                 6 14                                            
Private equity                             0                       0                       34                                           34                                                                                                                                                                                                                                   0                       0                       34                   34                                          
Other debt obligations                         0 0 0 0                 78 48 8 2                 0 0 0 0                                     78 48 8 2                                                                                                                                                                                                                             0 0 0 0                 78 48 8 2                 0 0 0 0             78 48 8 2                                        
Nuclear decommissioning trust fund investments subtotal                         1,946 [5] 2,018 [5]                     4,669 [5] 4,358 [5]                     0 [5] 0 [5]                                         6,615 [5] 6,376 [5]                                                                                                                                                                                                                                 1,946 [6] 2,018 [6]                     4,669 [6] 4,358 [6]                     0 [6] 0 [6]                 6,615 [6] 6,376 [6]                                            
Pledged assets for Zion Station decommissioning subtotal                             134 [7] 250 [7]                     628 [7] 570 [7]                     34 [7] 0 [7]                                         796 [7] 820 [7]                                                                                                                                                                                                                                 134 [8] 250 [8]                     628 [8] 570 [8]                     34 [8] 0 [8]                 796 [8] 820 [8]                                        
Mutual funds                                                                                                                                                                           22 23           0 0           0 0       22 23                                                                                                                                             36 [9] 36 [9]                     0 [9] 0 [9]                     0 [9] 0 [9]                     36 [9] 36 [9]                                
Rabbi trust investments subtotal                                 4 [10],[11] 4 [10],[11]                     0 [10],[11] 0 [10],[11]                     0 [10],[11] 0 [10],[11]                                         4 [10],[11] 4 [10],[11]                                             23             0             0         23                                 8 [12],[13] 7 [12],[13]         0 [12],[13] 0 [12],[13]         0 [12],[13] 0 [12],[13]     8 [12],[13] 7 [12],[13]                                                                         36 36                     0 0                     0 0                     36 36                                
Cash flow hedges                                     0 0 0 0                 481 724 (82) (45)                 761 992 (14) 0                                     1,242 1,716 (96) (45)                                                                                                                                                                                                                             0 0 0 0                 481 724 (82) (45)                 2 12 (14) 0                 483 736 (96) (45)                        
Other derivatives                                     0 2 (1) (2)                 1,211 1,695 (545) (667)                 29 53 (25) (25)                                     1,240 1,750 (571) (694)                                                                                                                                                                                                                             0 2 (1) (2)                 1,225 1,709 (545) (667)                 29 57 (58) (29)                 1,254 1,768 (604) (698)                        
Proprietary trading                                     0 0 0 0                 173 235 (171) (233)                 60 46 (28) (21)                                     233 281 (199) (254)                                                                                                                                                                                                                             0 0 0 0                 173 235 (171) (233)                 60 46 (28) (21)                 233 281 (199) (254)                        
Effect of netting and allocation of collateral received/(paid)                                     (1) [14] (3) [14] 1 [14] 1 [14]                 (1,167) [14] (1,848) [14] 749 [14] 914 [14]                 (40) [14] (38) [14] 33 [14] 23 [14]                                     (1,208) [14] (1,889) [14] 783 [14] 938 [14]                                                                                                                                                                                                                             (1) [14] (3) [14] 1 [14] 1 [14]                 (1,167) [14] (1,848) [14] 749 [14] 914 [14]                 (40) [14] (38) [14] 33 [14] 23 [14]                 (1,208) [14] (1,889) [14] 783 [14] 938 [14]                        
Mark-to-market subtotal                                     (1) [15] (1) [15] 0 (1)                 698 [15] 806 [15] (49) (31)                 810 [15] 1,053 [15] (34) (23)                                     1,507 [15] 1,858 [15] (83) (55)                                       0 0 [16],[17] 0 [17]         0 0 [16],[17] 0 [17]         4 (788) [16],[17] (975) [17]     4 (788) [16],[17] (975) [17]                               0 [18] 0 [18]         0 [18] 0 [18]         (4) [18] (9) [18]         (4) [18] (9) [18]                                                                     (1) [19] (1) [19] 0 [19] (1) [19]                 712 [19] 820 [19] (49) [19] (31) [19]                 51 [19] 77 [19] (67) [19] (27) [19]                 762 [19] 896 [19] (116) [19] (59) [19]                        
Deferred compensation (72)   (72)   (76) (17)   (17)   (20) 0 0                     (17) (20)                     0 0                                                                                           (8) (8) 0 0           (8) (8)           0 0                                       (21) (23) 0 0         (21) (23)         0 0                                                                         0 0                     (72) (76)                     0 0                                                                    
Total assets 8,659   8,659   9,601 8,996   8,996   9,477 2,157 2,690                     5,995 5,734                     844 1,053                                                                                           55 28 55 24           0 0           0 4                                       306 506 306 506         0 0         0 0                                                                         2,565 3,776                     6,009 5,748                     85 77                                                                    
Total liabilities (188)   (188)   (135) (100)   (100)   (75) 0 (1)                     (66) (51)                     (34) (23)                                                                                           (796) (983) 0 0           (8) (8)           (788) (975)                                       (25) (32) 0 0         (21) (23)         (4) (9)                                                                         0 (1)                     (121) (107)                     (67) (27)                                                                    
Total net assets 8,471   8,471   9,466 8,896   8,896   9,402 2,157 2,689                     5,929 5,683                     810 1,030                                                                                           (741) (955) 55 24           (8) (8)           (788) (971)                                       281 474 306 506         (21) (23)         (4) (9)                                                                         2,565 3,775                     5,888 5,641                     18 50                                                                    
Footnotes To Fair Value Assets And Liabilities Measured On Recurring Basis [Abstract]                                                                                                                                                                                                                                                                                                                                                                                                                                                                            
Net assets (liabilities) excluded from nuclear decommissioning trust fund investments                                                                                                                     84 32                                                                                                                                                                                                                                                                                                     84 32                                            
Net assets (liabilities) excluded from pledged assets                                                                                                                         8 4                                                                                                                                                                                                                                                                                                     8 4                                        
Cash surrender value of life insurance investments excluded from Rabbi Trust investments                                                                                                                             6 7                                                                                                                                                     14 13                                                                                                                                                 26 25                                
Collateral received from counterparties, net of collateral paid to counterparties                       2                     418 934                     7 15                                                                                                                                                                                                                                                                               2                     418 934                     7 15                                                                    
Fair value swap contract current asset           412   412   450                                                                                                                                                                                                                                                                                                                                                                                                                                                        
Fair value swap contract noncurrent asset           345   345   525                                                                                                                                                                                                                                                                                                                                                                                                                                                        
Fair value of energy swap contract current liability                                                                                                                                                                   1                                                                                                                                                                                                                                                                                                        
Fair value of energy swap contract noncurrent liability                                                                                                                                                                   30                                                                                                                                                                                                                                                                                                        
Fair value swap contract current liability                                                                                                                                                                   412 450                                                                                                                                                                                                                                                                                                      
Fair value swap contract noncurrent liability                                                                                                                                                                   345 525                                                                                                                                                                                                                                                                                                      
Fair value block contract current asset           2   2   5                                                                                                             2 5                                                                                                                                                                                                                                                                                                                                        
Fair value block contract current liabilities                                                                                                                                                                                                                                             2 5                                         2 5                                                                                                                                                                                
Fair Value Assets And Liabilities Measured On Recurring Basis Unobservable Input Reconciliation [Abstract]                                                                                                                                                                                                                                                                                                                                                                                                                                                                            
Beginning balance 82 33 50 (46)   964 1,279 1,030 931                                                                                                                       0   0 31 0 933 1,279 1,030 931                                                                 (875) (1,235) (971) (971)         (6)                                                     (7) (11) (9) (4) (2)                                                                                                                           31 0             0   0 51 33 50 (44) (2)        
Total realized / unrealized gains (losses)                                                                                                                                                                                                                                                                                                                                                                                                                                                                            
Included in income 21   8 82   21   8 80                                                                                                                         0   0 0 21 [20]   8 [20] 80 [21]                                                                                 2                                                           0 2 [22]                                                                                                                           0 0               0   21 [23]   8 [23] 80 [24] 2 [25]        
Included in other comprehensive income (3) (11) (12) 7   (178) (237) (233) 49                                                                                                                       0 0   0 0 (178) [26] (237) [27] (233) [26] 49 [27]                                                                                                                                                                                                                                                                           0 0             0 0   (3) [28] (11) [29] (12) [28] 7 [29] 0        
Included in payable for Zion Station decommissioning 3   3     3   3                                                                                                                               3 3 0   0                                                                                                                                                                                                                                                                             3 3                   0   0            
Included in regulatory assets (85) 1 (33) (2)                                                                                                                                                                                                                   87 [30],[31] 225 [32] 183 [30],[31] (39) [32]         (5)                                                     3 [33] 2 [34] 5 [33] (5) [34] 0                                                                                                                           0 0             0 0   (85) 1 (33) (2) 0        
Change in collateral 2 9 7 (8)   2 9 7 (8)                                                                                                                       0 0   0 0 2 9 7 (8)                                                                                                                                                                                                                                                                           0 0             0 0   2 9 7 (8) 0        
Purchases, sales, issuances, and settlements                                                                                                                                                                                                                                                                                                                                                                                                                                                                            
Purchases 17 12 48 12   17 12 48 12                                                                                                                       1 1   12 43 5 11 5 11                                                                                                                                                                                                                                                                           12 43             1 1   5 11 5 11 0        
Sales (12)   (12)     (12)   (12)                                                                                                                               (12) (12) 0   0                                                                                                                                                                                                                                                                             (12) (12)                   0   0            
Transfers out of Level 3 - Liability (7) 24 (41) 23   (7) 24 (41) 23                                                                                                                       0 0   0 0 (7) 24 (41) 23                                                                                                                                                                                                                                                                           0 0             0 0   (7) 24 (41) 23 0        
Ending balance 18 68 18 68   810 1,087 810 1,087                                                                                                                       1 1 0 34 34 776 1,086 776 1,086                                                                 (788) (1,010) (788) (1,010)         (9)                                                     (4) (9) (4) (9) 0                                                                                                                           34 34             1 1 0 (16) 67 (16) 67 0        
The amount of total gains (losses) included in income attributed to the change in unrealized gains (losses) related to assets and liabilities 30 1 23 78   30 1 23 78                                                                                                                       0 0   0 0 30 1 23 78                                                                                                                                                                                                                                                                           0 0             0 0   30 1 23 78 0        
Footnotes To Fair Value Assets And Liabilities Measured On Recurring Basis Unobservable Input Reconciliation [Abstract]                                                                                                                                                                                                                                                                                                                                                                                                                                                                            
Gain (loss) reclassified to results of operating due to the settlement of derivative contracts                                                                                                                                                   (9)   (15) 2                                                                                                                                                                                                                                                                                                 (9)   (15) 2          
Increase (decrease) in fair value related to the swap contract                                                                                                                                                   (65) (121) 2 199                                                                 65 121 (2) (199)                                                                                                                                                                                                                                          
Realized gains (losses) related to swap contract                                                                                                                                                   (108) (104) (220) (160)                                                                 108 104 220 160                                                                                                                                                                                                                                          
Increase (decrease) in fair value related to block contracts                                                                                                                                                   (2) (1) (3) 3                                                                                                                                       2 1 3 (3)                                                                                                                                                                    
Increase (decrease) in fair value related to floating-to-fixed energy swap contracts                                                                                                                                                                                                                           (86)   (35)                                                                                                                                                                                                                                            
Financial Instruments Financial Liabilities Balance Sheet Groupings [Abstract]                                                                                                                                                                                                                                                                                                                                                                                                                                                                            
Long-term debt (including amounts due within one year)                                                                                                                                                           3,678 3,679 3,857 3,792                                                                 5,601 5,001 6,131 5,411                                                                 2,222 2,222 2,411 2,402                                                                                                                                                   12,812 12,213 13,746 12,960
Long-term debt to financing trusts                                                                                                                                                                                                                                   206 206 176 176                                                                 184 184 172 173                                                                                                                                                   390 390 347 350
Spent nuclear fuel obligation                                                                                                                                                           1,019 1,018 897 876                                                                                                                                                                                                                                                                                                   1,019 1,018 897 876
Preferred securities of subsidiary                                                                                                                                                                                                                                                                                                           87 87 72 68                                                                                                                                                   87 87 72 68
Servicing Liability Valuation Techniques [Abstract]                                                                                                                                                                                                                                                                                                                                                                                                                                                                            
Proceeds from agreement under servicing liability $ 225   $ 225                                                                                                                                                                                                                                       $ 225                                                                                                                                                                                                                              
[1] Excludes certain cash equivalents considered to be held-to-maturity and not reported at fair value.
[2] Generation's NDT funds and Zion Station decommissioning pledged assets hold equity portfolios whose performance is benchmarked against established indices.
[3] Generation's NDT funds and Zion Station decommissioning pledged assets own commingled funds that invest in equity securities. Generation's NDT funds also own commingled funds that invest in fixed income securities. The commingled funds seek to out-perform certain established indices.
[4] Generation's NDT funds and Zion Station decommissioning pledged assets own commingled funds that invest in equity securities. Generation's NDT funds also own commingled funds that invest in fixed income securities. The commingled funds seek to out-perform certain established indices.
[5] Excludes net assets of $84 million and $32 million at June 30, 2011 and December 31, 2010, respectively. These items consist of receivables related to pending securities sales, interest and dividend receivables, and payables related to pending securities purchases.
[6] Excludes net assets of $84 million and $32 million at June 30, 2011 and December 31, 2010, respectively. These items consist of receivables related to pending securities sales, interest and dividend receivables, and payables related to pending securities purchases.
[7] Excludes net assets of $8 million and $4 million at June 30, 2011 and December 31, 2010, respectively. These items consist of receivables related to pending securities sales, interest and dividend receivables, and payables related to pending securities purchases.
[8] Excludes net assets of $8 million and $4 million at June 30, 2011 and December 31, 2010. These items consist of receivables related to pending securities sales, interest and dividend receivables, and payables related to pending securities purchases.
[9] Excludes $26 million and $25 million of the cash surrender value of life insurance investments at June 30, 2011 and December 31, 2010, respectively.
[10] Excludes $6 million and $7 million of the cash surrender value of life insurance investments at June 30, 2011 and December 31, 2010, respectively.
[11] The mutual funds held by the Rabbi trusts that are invested in common stock of Standard and Poor's 500 companies and Pennsylvania municipal bonds are primarily rated as investment grade.
[12] Excludes $14 million and $13 million of the cash surrender value of life insurance investments at June 30, 2011 and December 31, 2010, respectively.
[13] The mutual funds held by the Rabbi trusts invest in common stock of Standard and Poor's 500 companies and Pennsylvania municipal bonds that are primarily rated as investment grade.
[14] Includes collateral postings received from counterparties. Collateral received from counterparties, net of collateral paid to counterparties, totaled $418 million and $7 million allocated to Level 2 and Level 3 mark-to-market derivatives, respectively, as of June 30, 2011. Collateral received from counterparties, net of collateral paid to counterparties, totaled $2 million, $934 million and $15 million allocated to Level 1, Level 2 and Level 3 mark-to-market derivatives, respectively, as of December 31, 2010.
[15] The Level 3 balance includes current and noncurrent assets for Generation of $412 million and $345 million at June 30, 2011 and $450 million and $525 million at December 31, 2010, respectively, related to the fair value of Generation's financial swap contract with ComEd; and current assets of $2 million and $5 million at June 30, 2011 and December 31, 2010, respectively, related to the fair value of Generation's block contracts with PECO. All of the mark-to-market balances Generation carries associated with the financial swap contract with ComEd and the block contracts with PECO eliminate upon consolidation in Exelon's Consolidated Financial Statements.
[16] The Level 3 balance includes the current and noncurrent liability of $1 million and $30 million at June 30, 2011, respectively, related to floating-to-fixed energy swap contracts with unaffiliated suppliers. The current liability is included in other current liabilities in ComEd's Consolidated Balance Sheets.
[17] The Level 3 balance includes the current and noncurrent liability of $412 million and $345 million at June 30, 2011, respectively, and $450 million and $525 million at December 31, 2010, respectively, related to the fair value of ComEd's financial swap contract with Generation which eliminates upon consolidation in Exelon's Consolidated Financial Statements.
[18] The Level 3 balances include current liabilities of $2 million and $5 million at June 30, 2011 and December 31, 2010, respectively, related to the fair value of PECO's block contracts with Generation that eliminate upon consolidation in Exelon's Consolidated Financial Statements.
[19] The Level 3 balance does not include current and noncurrent assets for Generation and current and noncurrent liabilities for ComEd of $412 million and $345 million at June 30, 2011 and $450 million and $525 million at December 31, 2010, respectively, related to the fair value of Generation's financial swap contract with ComEd; and current assets for Generation and current liabilities for PECO of $2 million and $5 million at June 30, 2011 and December 31, 2010, respectively, related to the fair value of Generation's block contracts with PECO, which eliminate upon consolidation in Exelon's Consolidated Financial Statements.
[20] Includes the reclassification of $9 million and $15 million of realized losses due to the settlement of derivative contracts recorded in results of operations for the three and six months ended June 30, 2011, respectively.
[21] Includes the reclassification of $2 million of realized gains due to the settlement of derivative contracts recorded in results of operations for the six months ended June 30, 2010. The reclassification due to settlement of derivative contracts for the three months ended June 30, 2011 was insignificant.
[22] The servicing liability related to PECO's accounts receivable agreement was released in accordance with new guidance on accounting for transfers of financial assets that was adopted on January 1, 2010.
[23] Includes the reclassification of $9 million and $15 million of realized losses due to the settlement of derivative contracts recorded in results of operations for the three and six months ended June 30, 2011, respectively.
[24] Includes the reclassification of $2 million of realized gains due to the settlement of derivative contracts recorded in results of operations for the six months ended June 30, 2010. The reclassification due to settlement of derivative contracts for the three months June 30, 2010 was insignificant.
[25] The servicing liability related to PECO's accounts receivable agreement was released in accordance with new guidance on accounting for transfers of financial assets that was adopted on January 1, 2010. See Note 7 - Debt and Credit Agreements for additional information.
[26] Includes $65 million of decreases in fair value and $2 million of increases in fair value and realized losses reclassified from OCI due to settlements of $108 million and $220 million associated with Generation's financial swap contract with ComEd and $2 million and $3 million of decreases in fair value due to settlement of Generation's block contracts with PECO for the three and six months ended June 30, 2011, respectively. All items eliminate upon consolidation in Exelon's Consolidated Financial Statements
[27] Includes $121 million of decreases in fair value and $199 million of increases in fair value and realized losses due to settlements of $104 million and $160 million associated with Generation's financial swap contract with ComEd and $1 million of decreases in fair value and $3 million of increases in fair value of Generation's block contracts with PECO for the three and six months ended June 30, 2010. All items eliminate upon consolidation in Exelon's Consolidated Financial Statements.
[28] Excludes $65 million of decreases and $2 million of increases in fair value and $108 million and $220 million of realized losses due to settlements associated with Generation's financial swap contract with ComEd and $2 million and $3 million of changes in the fair value of Generation's block contracts with PECO for the three months and six months ended June 30, 2011, respectively. All items eliminate upon consolidation in Exelon's Consolidated Financial Statements.
[29] Excludes $121 million of decreases in fair value and $199 million of increases in fair value and realized losses due to settlements of $104 million and $160 million associated with Generation's financial swap contract with ComEd and $1 million of decreases in fair value and $3 million of increases in fair value of Generation's block contracts with PECO for the three and six months ended June 30, 2010, respectively. All amounts eliminate upon consolidation in Exelon's Consolidated Financial Statements.
[30] Includes $65 million of increases in fair value and $2 million of decreases in fair value and $108 million and $220 million of realized gains due to settlements associated with ComEd's financial swap contract with Generation for the three and six months ended June 30, 2011, respectively. All items eliminate upon consolidation in Exelon's Consolidated Financial Statements.
[31] Includes $86 million and $35 million of decreases in the fair value of floating-to-fixed energy swap contracts with unaffiliated suppliers for the three and six months ended June 30, 2011, respectively
[32] Includes $121 million of increases in fair value and $199 million of decreases in fair value and realized gains due to settlements of $104 million and $160 million associated with ComEd's financial swap contract with Generation for the three and six months ended June 30, 2010, respectively. All items eliminate upon consolidation in Exelon's Consolidated Financial Statements.
[33] Includes increases of $2 million and $3 million related to the settlement of PECO's block contract with Generation for the three and six months ended June 30, 2011, respectively, which eliminate upon consolidation in Exelon's Consolidated Financial Statements.
[34] Includes a $1 million increase in fair value and a $3 million decrease associated with PECO's block contract with Generation, for the three and six months ended June 30, 2010, respectively, which eliminate upon consolidation in Exelon's Consolidated Financial Statements.