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Fair Value of Financial Assets and Liabilities - Fair Value Measurements of Assets and Liabilities, Recurring and Nonrecurring (Details) - USD ($)
$ in Millions
 3 Months Ended 6 Months Ended 9 Months Ended
Sep. 30, 2021
Jun. 30, 2021
Sep. 30, 2021
Dec. 31, 2020
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Mark-to-market derivative liabilities (current liabilities) $ 1,717   $ 1,717 $ 295
Derivative Liability, Noncurrent 721   721 473
Margin Deposit Assets (2,084)   (2,084) (209)
Unrealized Gain (Loss) on Investments (179)   (83)  
Fair Value, Recurring [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Cash equivalents 2,573   2,573 686
DPP consideration 501   501 639
Assets, Fair Value Disclosure 21,421   21,421 17,776
Deferred Compensation Liability, Current and Noncurrent (149)   (149) (145)
Total Liabilities (2,579)   (2,579) (910)
Fair Value, Net Asset (Liability) 18,842   18,842 16,866
Derivative Asset, Notional Amount 728   728 1,043
Margin Deposit Assets (2,084)   (2,084) (209)
Derivative, Notional Amount 194   194 104
Derivative Instruments Not Designated as Hedging Instruments, Asset, at Fair Value 0   0 2
Fair Value, Recurring [Member] | Commodity Derivative Liabilites [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Total mark-to-market derivative liabilities (2,430)   (2,430) (765)
Fair Value, Recurring [Member] | Economic Hedging Instrument Liabilites [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Total mark-to-market derivative liabilities (21,872)   (21,872) (4,265)
Fair Value, Recurring [Member] | Proprietary Trading Liabilities [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Total mark-to-market derivative liabilities (58)   (58) (25)
Fair Value, Recurring [Member] | Effects of Netting and Allocation of Collateral Liabilites [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Total mark-to-market derivative liabilities 19,500   19,500 3,525
Fair Value, Recurring [Member] | Cash and Cash Equivalents [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Cash equivalents 689   689 409
Fair Value, Recurring [Member] | Restricted cash member [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Cash equivalents 222   222 59
Fair Value, Recurring [Member] | Other Assets [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Cash equivalents 54   54 53
Fair Value, Recurring [Member] | Nuclear Decommissioning Trust Fund Investments [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 15,732   15,732 14,780
Net assets (liabilities) excluded from nuclear decommissioning trust fund investments 130   130 181
Financial Instruments Sold, Not yet Purchased, Corporate Debt (50)   (50) (62)
Fair Value, Recurring [Member] | Cash Equivalents NDT [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 782   782 305
Fair Value, Recurring [Member] | Equity Securities Nuclear Decommissioning Trust Fund [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 7,650   7,650 7,525
Fair Value, Recurring [Member] | Fixed Income Securities [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 5,065   5,065 4,926
Fair Value, Recurring [Member] | Corporate Debt Securities [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 1,442   1,442 1,770
Fair Value, Recurring [Member] | US Treasury and Government [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 2,221   2,221 1,997
Fair Value, Recurring [Member] | Debt Security, Government, Non-US [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 54   54 56
Fair Value, Recurring [Member] | State and municipal debt [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 29   29 101
Fair Value, Recurring [Member] | Other Fixed Income [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 1,319   1,319 1,002
Fair Value, Recurring [Member] | Middle Market Lending [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 779   779 841
Fair Value, Recurring [Member] | Private Equity Funds [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 654   654 504
Fair Value, Recurring [Member] | Real Estate Funds [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 802   802 679
Fair Value, Recurring [Member] | Rabbi Trust Investments [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 312   312 283
Fair Value, Recurring [Member] | Cash Equivalents [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 65   65 60
Fair Value, Recurring [Member] | Mutual Funds [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 104   104 91
Fair Value, Recurring [Member] | Fixed Income Investments [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 10   10 11
Fair Value, Recurring [Member] | 6311 Life Insurance [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 133   133 121
Fair Value, Recurring [Member] | Equity Securities [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 137   137 195
Fair Value, Recurring [Member] | Commodity derivative assets [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Derivative Asset 2,166   2,166 1,193
Fair Value, Recurring [Member] | Economic Hedges [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Derivative Asset 23,243   23,243 4,258
Fair Value, Recurring [Member] | Proprietary Trading [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Derivative Asset 68   68 44
Fair Value, Recurring [Member] | Effects of netting and allocation of collateral [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Derivative Asset (21,145)   (21,145) (3,109)
Fair Value, Inputs, Level 1 [Member] | Fair Value, Recurring [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Cash equivalents 2,573   2,573 686
DPP consideration 0   0 0
Assets, Fair Value Disclosure 11,181   11,181 7,137
Deferred Compensation Liability, Current and Noncurrent 0   0 0
Total Liabilities (3)   (3) (142)
Fair Value, Net Asset (Liability) 11,178   11,178 6,995
Collateral received from counterparties, net of collateral paid to counterparties (345)   (345) (67)
Fair Value, Inputs, Level 1 [Member] | Fair Value, Recurring [Member] | Commodity Derivative Liabilites [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Total mark-to-market derivative liabilities (3)   (3) (142)
Fair Value, Inputs, Level 1 [Member] | Fair Value, Recurring [Member] | Economic Hedging Instrument Liabilites [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Total mark-to-market derivative liabilities (4,126)   (4,126) (682)
Fair Value, Inputs, Level 1 [Member] | Fair Value, Recurring [Member] | Proprietary Trading Liabilities [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Total mark-to-market derivative liabilities 0   0 0
Fair Value, Inputs, Level 1 [Member] | Fair Value, Recurring [Member] | Effects of Netting and Allocation of Collateral Liabilites [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Total mark-to-market derivative liabilities 4,123   4,123 540
Fair Value, Inputs, Level 1 [Member] | Fair Value, Recurring [Member] | Nuclear Decommissioning Trust Fund Investments [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 7,243   7,243 5,967
Fair Value, Inputs, Level 1 [Member] | Fair Value, Recurring [Member] | Cash Equivalents NDT [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 647   647 210
Fair Value, Inputs, Level 1 [Member] | Fair Value, Recurring [Member] | Equity Securities Nuclear Decommissioning Trust Fund [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 4,373   4,373 3,886
Fair Value, Inputs, Level 1 [Member] | Fair Value, Recurring [Member] | Fixed Income Securities [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 2,223   2,223 1,871
Fair Value, Inputs, Level 1 [Member] | Fair Value, Recurring [Member] | Corporate Debt Securities [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 0   0 0
Fair Value, Inputs, Level 1 [Member] | Fair Value, Recurring [Member] | US Treasury and Government [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 2,192   2,192 1,871
Fair Value, Inputs, Level 1 [Member] | Fair Value, Recurring [Member] | Debt Security, Government, Non-US [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 0   0 0
Fair Value, Inputs, Level 1 [Member] | Fair Value, Recurring [Member] | State and municipal debt [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 0   0 0
Fair Value, Inputs, Level 1 [Member] | Fair Value, Recurring [Member] | Other Fixed Income [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 31   31 0
Fair Value, Inputs, Level 1 [Member] | Fair Value, Recurring [Member] | Middle Market Lending [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 0   0 0
Fair Value, Inputs, Level 1 [Member] | Fair Value, Recurring [Member] | Private Equity Funds [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 0   0 0
Fair Value, Inputs, Level 1 [Member] | Fair Value, Recurring [Member] | Real Estate Funds [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 0   0 0
Fair Value, Inputs, Level 1 [Member] | Fair Value, Recurring [Member] | Rabbi Trust Investments [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 169   169 151
Fair Value, Inputs, Level 1 [Member] | Fair Value, Recurring [Member] | Cash Equivalents [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 65   65 60
Fair Value, Inputs, Level 1 [Member] | Fair Value, Recurring [Member] | Mutual Funds [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 104   104 91
Fair Value, Inputs, Level 1 [Member] | Fair Value, Recurring [Member] | Fixed Income Investments [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 0   0 0
Fair Value, Inputs, Level 1 [Member] | Fair Value, Recurring [Member] | 6311 Life Insurance [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 0   0 0
Fair Value, Inputs, Level 1 [Member] | Fair Value, Recurring [Member] | Equity Securities [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 137   137 195
Fair Value, Inputs, Level 1 [Member] | Fair Value, Recurring [Member] | Commodity derivative assets [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Derivative Asset 1,059   1,059 138
Fair Value, Inputs, Level 1 [Member] | Fair Value, Recurring [Member] | Economic Hedges [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Derivative Asset 5,527   5,527 745
Fair Value, Inputs, Level 1 [Member] | Fair Value, Recurring [Member] | Proprietary Trading [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Derivative Asset 0   0 0
Fair Value, Inputs, Level 1 [Member] | Fair Value, Recurring [Member] | Effects of netting and allocation of collateral [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Derivative Asset (4,468)   (4,468) (607)
Fair Value, Inputs, Level 2 [Member] | Fair Value, Recurring [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Cash equivalents 0   0 0
DPP consideration 501   501 639
Assets, Fair Value Disclosure 4,578   4,578 5,052
Deferred Compensation Liability, Current and Noncurrent (149)   (149) (145)
Total Liabilities (214)   (214) (176)
Fair Value, Net Asset (Liability) 4,364   4,364 4,876
Collateral received from counterparties, net of collateral paid to counterparties (710)   (710) 321
Fair Value, Inputs, Level 2 [Member] | Fair Value, Recurring [Member] | Commodity Derivative Liabilites [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Total mark-to-market derivative liabilities (65)   (65) (31)
Fair Value, Inputs, Level 2 [Member] | Fair Value, Recurring [Member] | Economic Hedging Instrument Liabilites [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Total mark-to-market derivative liabilities (9,192)   (9,192) (1,928)
Fair Value, Inputs, Level 2 [Member] | Fair Value, Recurring [Member] | Proprietary Trading Liabilities [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Total mark-to-market derivative liabilities (32)   (32) (21)
Fair Value, Inputs, Level 2 [Member] | Fair Value, Recurring [Member] | Effects of Netting and Allocation of Collateral Liabilites [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Total mark-to-market derivative liabilities 9,159   9,159 1,918
Fair Value, Inputs, Level 2 [Member] | Fair Value, Recurring [Member] | Nuclear Decommissioning Trust Fund Investments [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 3,148   3,148 3,981
Fair Value, Inputs, Level 2 [Member] | Fair Value, Recurring [Member] | Cash Equivalents NDT [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 135   135 95
Fair Value, Inputs, Level 2 [Member] | Fair Value, Recurring [Member] | Equity Securities Nuclear Decommissioning Trust Fund [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 1,717   1,717 2,077
Fair Value, Inputs, Level 2 [Member] | Fair Value, Recurring [Member] | Fixed Income Securities [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 1,296   1,296 1,809
Fair Value, Inputs, Level 2 [Member] | Fair Value, Recurring [Member] | Corporate Debt Securities [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 1,155   1,155 1,485
Fair Value, Inputs, Level 2 [Member] | Fair Value, Recurring [Member] | US Treasury and Government [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 29   29 126
Fair Value, Inputs, Level 2 [Member] | Fair Value, Recurring [Member] | Debt Security, Government, Non-US [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 54   54 56
Fair Value, Inputs, Level 2 [Member] | Fair Value, Recurring [Member] | State and municipal debt [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 29   29 101
Fair Value, Inputs, Level 2 [Member] | Fair Value, Recurring [Member] | Other Fixed Income [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 29   29 41
Fair Value, Inputs, Level 2 [Member] | Fair Value, Recurring [Member] | Middle Market Lending [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 0   0 0
Fair Value, Inputs, Level 2 [Member] | Fair Value, Recurring [Member] | Private Equity Funds [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 0   0 0
Fair Value, Inputs, Level 2 [Member] | Fair Value, Recurring [Member] | Real Estate Funds [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 0   0 0
Fair Value, Inputs, Level 2 [Member] | Fair Value, Recurring [Member] | Rabbi Trust Investments [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 109   109 98
Fair Value, Inputs, Level 2 [Member] | Fair Value, Recurring [Member] | Cash Equivalents [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 0   0 0
Fair Value, Inputs, Level 2 [Member] | Fair Value, Recurring [Member] | Mutual Funds [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 0   0 0
Fair Value, Inputs, Level 2 [Member] | Fair Value, Recurring [Member] | Fixed Income Investments [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 10   10 11
Fair Value, Inputs, Level 2 [Member] | Fair Value, Recurring [Member] | 6311 Life Insurance [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 99   99 87
Fair Value, Inputs, Level 2 [Member] | Fair Value, Recurring [Member] | Equity Securities [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 0   0 0
Fair Value, Inputs, Level 2 [Member] | Fair Value, Recurring [Member] | Commodity derivative assets [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Derivative Asset 820   820 334
Fair Value, Inputs, Level 2 [Member] | Fair Value, Recurring [Member] | Economic Hedges [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Derivative Asset 10,633   10,633 1,914
Fair Value, Inputs, Level 2 [Member] | Fair Value, Recurring [Member] | Proprietary Trading [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Derivative Asset 56   56 17
Fair Value, Inputs, Level 2 [Member] | Fair Value, Recurring [Member] | Effects of netting and allocation of collateral [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Derivative Asset (9,869)   (9,869) (1,597)
Fair Value, Inputs, Level 3 [Member] | Fair Value, Recurring [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Cash equivalents 0   0 0
DPP consideration 0   0 0
Assets, Fair Value Disclosure 796   796 1,252
Deferred Compensation Liability, Current and Noncurrent 0   0 0
Total Liabilities (2,362)   (2,362) (592)
Fair Value, Net Asset (Liability) (1,566)   (1,566) 660
Collateral received from counterparties, net of collateral paid to counterparties (590)   (590) 162
Fair Value, Inputs, Level 3 [Member] | Fair Value, Recurring [Member] | Commodity Derivative Liabilites [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Total mark-to-market derivative liabilities (2,362)   (2,362) (592)
Fair Value, Inputs, Level 3 [Member] | Fair Value, Recurring [Member] | Economic Hedging Instrument Liabilites [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Total mark-to-market derivative liabilities (8,554)   (8,554) (1,655)
Fair Value, Inputs, Level 3 [Member] | Fair Value, Recurring [Member] | Proprietary Trading Liabilities [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Total mark-to-market derivative liabilities (26)   (26) (4)
Fair Value, Inputs, Level 3 [Member] | Fair Value, Recurring [Member] | Effects of Netting and Allocation of Collateral Liabilites [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Total mark-to-market derivative liabilities 6,218   6,218 1,067
Fair Value, Inputs, Level 3 [Member] | Fair Value, Recurring [Member] | Nuclear Decommissioning Trust Fund Investments [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 475   475 497
Fair Value, Inputs, Level 3 [Member] | Fair Value, Recurring [Member] | Cash Equivalents NDT [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 0   0 0
Fair Value, Inputs, Level 3 [Member] | Fair Value, Recurring [Member] | Equity Securities Nuclear Decommissioning Trust Fund [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 1   1 0
Fair Value, Inputs, Level 3 [Member] | Fair Value, Recurring [Member] | Fixed Income Securities [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 287   287 285
Fair Value, Inputs, Level 3 [Member] | Fair Value, Recurring [Member] | Corporate Debt Securities [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 287   287 285
Fair Value, Inputs, Level 3 [Member] | Fair Value, Recurring [Member] | US Treasury and Government [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 0   0 0
Fair Value, Inputs, Level 3 [Member] | Fair Value, Recurring [Member] | Debt Security, Government, Non-US [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 0   0 0
Fair Value, Inputs, Level 3 [Member] | Fair Value, Recurring [Member] | State and municipal debt [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 0   0 0
Fair Value, Inputs, Level 3 [Member] | Fair Value, Recurring [Member] | Other Fixed Income [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 0   0 0
Fair Value, Inputs, Level 3 [Member] | Fair Value, Recurring [Member] | Middle Market Lending [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 187   187 212
Fair Value, Inputs, Level 3 [Member] | Fair Value, Recurring [Member] | Private Equity Funds [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 0   0 0
Fair Value, Inputs, Level 3 [Member] | Fair Value, Recurring [Member] | Real Estate Funds [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 0   0 0
Fair Value, Inputs, Level 3 [Member] | Fair Value, Recurring [Member] | Rabbi Trust Investments [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 34   34 34
Fair Value, Inputs, Level 3 [Member] | Fair Value, Recurring [Member] | Cash Equivalents [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 0   0 0
Fair Value, Inputs, Level 3 [Member] | Fair Value, Recurring [Member] | Mutual Funds [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 0   0 0
Fair Value, Inputs, Level 3 [Member] | Fair Value, Recurring [Member] | Fixed Income Investments [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 0   0 0
Fair Value, Inputs, Level 3 [Member] | Fair Value, Recurring [Member] | 6311 Life Insurance [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 34   34 34
Fair Value, Inputs, Level 3 [Member] | Fair Value, Recurring [Member] | Equity Securities [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 0   0 0
Fair Value, Inputs, Level 3 [Member] | Fair Value, Recurring [Member] | Commodity derivative assets [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Derivative Asset 287   287 721
Fair Value, Inputs, Level 3 [Member] | Fair Value, Recurring [Member] | Economic Hedges [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Derivative Asset 7,083   7,083 1,599
Fair Value, Inputs, Level 3 [Member] | Fair Value, Recurring [Member] | Proprietary Trading [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Derivative Asset 12   12 27
Fair Value, Inputs, Level 3 [Member] | Fair Value, Recurring [Member] | Effects of netting and allocation of collateral [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Derivative Asset (6,808)   (6,808) (905)
Fair Value Measured at Net Asset Value Per Share [Member] | Fair Value, Recurring [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Cash equivalents 0   0 0
DPP consideration 0   0 0
Assets, Fair Value Disclosure 4,866   4,866 4,335
Deferred Compensation Liability, Current and Noncurrent 0   0 0
Total Liabilities 0   0 0
Fair Value, Net Asset (Liability) 4,866   4,866 4,335
Fair Value Measured at Net Asset Value Per Share [Member] | Fair Value, Recurring [Member] | Commodity Derivative Liabilites [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Total mark-to-market derivative liabilities 0   0 0
Fair Value Measured at Net Asset Value Per Share [Member] | Fair Value, Recurring [Member] | Economic Hedging Instrument Liabilites [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Total mark-to-market derivative liabilities 0   0 0
Fair Value Measured at Net Asset Value Per Share [Member] | Fair Value, Recurring [Member] | Proprietary Trading Liabilities [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Total mark-to-market derivative liabilities 0   0 0
Fair Value Measured at Net Asset Value Per Share [Member] | Fair Value, Recurring [Member] | Effects of Netting and Allocation of Collateral Liabilites [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Total mark-to-market derivative liabilities 0   0 0
Fair Value Measured at Net Asset Value Per Share [Member] | Fair Value, Recurring [Member] | Nuclear Decommissioning Trust Fund Investments [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 4,866   4,866 4,335
Fair Value Measured at Net Asset Value Per Share [Member] | Fair Value, Recurring [Member] | Cash Equivalents NDT [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 0   0 0
Fair Value Measured at Net Asset Value Per Share [Member] | Fair Value, Recurring [Member] | Equity Securities Nuclear Decommissioning Trust Fund [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 1,559   1,559 1,562
Fair Value Measured at Net Asset Value Per Share [Member] | Fair Value, Recurring [Member] | Fixed Income Securities [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 1,259   1,259 961
Fair Value Measured at Net Asset Value Per Share [Member] | Fair Value, Recurring [Member] | Corporate Debt Securities [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 0   0 0
Fair Value Measured at Net Asset Value Per Share [Member] | Fair Value, Recurring [Member] | US Treasury and Government [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 0   0 0
Fair Value Measured at Net Asset Value Per Share [Member] | Fair Value, Recurring [Member] | Debt Security, Government, Non-US [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 0   0 0
Fair Value Measured at Net Asset Value Per Share [Member] | Fair Value, Recurring [Member] | State and municipal debt [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 0   0 0
Fair Value Measured at Net Asset Value Per Share [Member] | Fair Value, Recurring [Member] | Other Fixed Income [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 1,259   1,259 961
Fair Value Measured at Net Asset Value Per Share [Member] | Fair Value, Recurring [Member] | Middle Market Lending [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 592   592 629
Fair Value Measured at Net Asset Value Per Share [Member] | Fair Value, Recurring [Member] | Private Equity Funds [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 654   654 504
Fair Value Measured at Net Asset Value Per Share [Member] | Fair Value, Recurring [Member] | Real Estate Funds [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 802   802 679
Fair Value Measured at Net Asset Value Per Share [Member] | Fair Value, Recurring [Member] | Rabbi Trust Investments [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 0   0 0
Fair Value Measured at Net Asset Value Per Share [Member] | Fair Value, Recurring [Member] | Cash Equivalents [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 0   0 0
Fair Value Measured at Net Asset Value Per Share [Member] | Fair Value, Recurring [Member] | Mutual Funds [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 0   0 0
Fair Value Measured at Net Asset Value Per Share [Member] | Fair Value, Recurring [Member] | Fixed Income Investments [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 0   0 0
Fair Value Measured at Net Asset Value Per Share [Member] | Fair Value, Recurring [Member] | 6311 Life Insurance [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 0   0 0
Fair Value Measured at Net Asset Value Per Share [Member] | Fair Value, Recurring [Member] | Equity Securities [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 0   0 0
Fair Value Measured at Net Asset Value Per Share [Member] | Fair Value, Recurring [Member] | Commodity derivative assets [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Derivative Asset 0   0 0
Fair Value Measured at Net Asset Value Per Share [Member] | Fair Value, Recurring [Member] | Economic Hedges [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Derivative Asset 0   0 0
Fair Value Measured at Net Asset Value Per Share [Member] | Fair Value, Recurring [Member] | Proprietary Trading [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Derivative Asset 0   0 0
Fair Value Measured at Net Asset Value Per Share [Member] | Fair Value, Recurring [Member] | Effects of netting and allocation of collateral [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Derivative Asset 0   0 0
Exelon Generation Co L L C [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Derivative Liability, Fair Value, Amount Not Offset Against Collateral 2,554   2,554 297
Mark-to-market derivative liabilities (current liabilities) 1,709   1,709 262
Derivative Liability, Noncurrent 511   511 205
Margin Deposit Assets (2,084)   (2,084) (209)
Unrealized Gain (Loss) on Investments (179)   (83)  
Exelon Generation Co L L C [Member] | Fair Value, Recurring [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Cash equivalents 1,673   1,673 124
DPP consideration 501   501 639
Assets, Fair Value Disclosure 20,281   20,281 16,992
Deferred Compensation Liability, Current and Noncurrent (44)   (44) (42)
Total Liabilities (2,260)   (2,260) (506)
Fair Value, Net Asset (Liability) 18,021   18,021 16,486
Derivative Asset, Notional Amount 728   728 1,043
Margin Deposit Assets (2,084)   (2,084) (209)
Derivative, Notional Amount 194   194 104
Derivative Instruments Not Designated as Hedging Instruments, Asset, at Fair Value 0   0 2
Exelon Generation Co L L C [Member] | Fair Value, Recurring [Member] | Investments in Equity        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Unrealized Gain (Loss) on Investments   $ 220    
Exelon Generation Co L L C [Member] | Fair Value, Recurring [Member] | Commodity Derivative Liabilites [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Total mark-to-market derivative liabilities (2,216)   (2,216) (464)
Exelon Generation Co L L C [Member] | Fair Value, Recurring [Member] | Economic Hedging Instrument Liabilites [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Total mark-to-market derivative liabilities (21,658)   (21,658) (3,964)
Exelon Generation Co L L C [Member] | Fair Value, Recurring [Member] | Proprietary Trading Liabilities [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Total mark-to-market derivative liabilities (58)   (58) (25)
Exelon Generation Co L L C [Member] | Fair Value, Recurring [Member] | Effects of Netting and Allocation of Collateral Liabilites [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Total mark-to-market derivative liabilities 19,500   19,500 3,525
Exelon Generation Co L L C [Member] | Fair Value, Recurring [Member] | Cash and Cash Equivalents [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Cash equivalents 292   292 171
Exelon Generation Co L L C [Member] | Fair Value, Recurring [Member] | Restricted cash member [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Cash equivalents 54   54 20
Exelon Generation Co L L C [Member] | Fair Value, Recurring [Member] | Nuclear Decommissioning Trust Fund Investments [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 15,732   15,732 14,780
Net assets (liabilities) excluded from nuclear decommissioning trust fund investments 130   130 181
Exelon Generation Co L L C [Member] | Fair Value, Recurring [Member] | Cash Equivalents NDT [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 782   782 305
Exelon Generation Co L L C [Member] | Fair Value, Recurring [Member] | Equity Securities Nuclear Decommissioning Trust Fund [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 7,650   7,650 7,525
Exelon Generation Co L L C [Member] | Fair Value, Recurring [Member] | Fixed Income Securities [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 5,065   5,065 4,926
Exelon Generation Co L L C [Member] | Fair Value, Recurring [Member] | Corporate Debt Securities [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 1,442   1,442 1,770
Exelon Generation Co L L C [Member] | Fair Value, Recurring [Member] | US Treasury and Government [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 2,221   2,221 1,997
Exelon Generation Co L L C [Member] | Fair Value, Recurring [Member] | Debt Security, Government, Non-US [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 54   54 56
Exelon Generation Co L L C [Member] | Fair Value, Recurring [Member] | State and municipal debt [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 29   29 101
Exelon Generation Co L L C [Member] | Fair Value, Recurring [Member] | Other Fixed Income [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 1,319   1,319 1,002
Exelon Generation Co L L C [Member] | Fair Value, Recurring [Member] | Middle Market Lending [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 779   779 841
Exelon Generation Co L L C [Member] | Fair Value, Recurring [Member] | Private Equity Funds [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 654   654 504
Exelon Generation Co L L C [Member] | Fair Value, Recurring [Member] | Real Estate Funds [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 802   802 679
Exelon Generation Co L L C [Member] | Fair Value, Recurring [Member] | Rabbi Trust Investments [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 72   72 61
Exelon Generation Co L L C [Member] | Fair Value, Recurring [Member] | Cash Equivalents [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 4   4 4
Exelon Generation Co L L C [Member] | Fair Value, Recurring [Member] | Mutual Funds [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 35   35 29
Exelon Generation Co L L C [Member] | Fair Value, Recurring [Member] | Fixed Income Investments [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 0   0 0
Exelon Generation Co L L C [Member] | Fair Value, Recurring [Member] | 6311 Life Insurance [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 33   33 28
Exelon Generation Co L L C [Member] | Fair Value, Recurring [Member] | Equity Securities [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 137   137 195
Exelon Generation Co L L C [Member] | Fair Value, Recurring [Member] | Commodity derivative assets [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Derivative Asset 2,166   2,166 1,193
Exelon Generation Co L L C [Member] | Fair Value, Recurring [Member] | Economic Hedges [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Derivative Asset 23,243   23,243 4,258
Exelon Generation Co L L C [Member] | Fair Value, Recurring [Member] | Proprietary Trading [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Derivative Asset 68   68 44
Exelon Generation Co L L C [Member] | Fair Value, Recurring [Member] | Effects of netting and allocation of collateral [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Derivative Asset (21,145)   (21,145) (3,109)
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Recurring [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Cash equivalents 1,673   1,673 124
DPP consideration 0   0 0
Assets, Fair Value Disclosure 10,151   10,151 6,457
Deferred Compensation Liability, Current and Noncurrent 0   0 0
Total Liabilities (3)   (3) (142)
Fair Value, Net Asset (Liability) 10,148   10,148 6,315
Collateral received from counterparties, net of collateral paid to counterparties (345)   (345) (67)
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Recurring [Member] | Commodity Derivative Liabilites [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Total mark-to-market derivative liabilities (3)   (3) (142)
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Recurring [Member] | Economic Hedging Instrument Liabilites [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Total mark-to-market derivative liabilities (4,126)   (4,126) (682)
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Recurring [Member] | Proprietary Trading Liabilities [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Total mark-to-market derivative liabilities 0   0 0
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Recurring [Member] | Effects of Netting and Allocation of Collateral Liabilites [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Total mark-to-market derivative liabilities 4,123   4,123 540
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Recurring [Member] | Nuclear Decommissioning Trust Fund Investments [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 7,243   7,243 5,967
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Recurring [Member] | Cash Equivalents NDT [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 647   647 210
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Recurring [Member] | Equity Securities Nuclear Decommissioning Trust Fund [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 4,373   4,373 3,886
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Recurring [Member] | Fixed Income Securities [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 2,223   2,223 1,871
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Recurring [Member] | Corporate Debt Securities [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 0   0 0
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Recurring [Member] | US Treasury and Government [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 2,192   2,192 1,871
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Recurring [Member] | Debt Security, Government, Non-US [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 0   0 0
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Recurring [Member] | State and municipal debt [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 0   0 0
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Recurring [Member] | Other Fixed Income [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 31   31 0
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Recurring [Member] | Middle Market Lending [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 0   0 0
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Recurring [Member] | Private Equity Funds [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 0   0 0
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Recurring [Member] | Real Estate Funds [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 0   0 0
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Recurring [Member] | Rabbi Trust Investments [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 39   39 33
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Recurring [Member] | Cash Equivalents [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 4   4 4
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Recurring [Member] | Mutual Funds [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 35   35 29
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Recurring [Member] | Fixed Income Investments [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 0   0 0
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Recurring [Member] | 6311 Life Insurance [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 0   0 0
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Recurring [Member] | Equity Securities [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 137   137 195
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Recurring [Member] | Commodity derivative assets [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Derivative Asset 1,059   1,059 138
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Recurring [Member] | Economic Hedges [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Derivative Asset 5,527   5,527 745
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Recurring [Member] | Proprietary Trading [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Derivative Asset 0   0 0
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Recurring [Member] | Effects of netting and allocation of collateral [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Derivative Asset (4,468)   (4,468) (607)
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Recurring [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Cash equivalents 0   0 0
DPP consideration 501   501 639
Assets, Fair Value Disclosure 4,502   4,502 4,982
Deferred Compensation Liability, Current and Noncurrent (44)   (44) (42)
Total Liabilities (109)   (109) (73)
Fair Value, Net Asset (Liability) 4,393   4,393 4,909
Collateral received from counterparties, net of collateral paid to counterparties (710)   (710) 321
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Recurring [Member] | Commodity Derivative Liabilites [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Total mark-to-market derivative liabilities (65)   (65) (31)
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Recurring [Member] | Economic Hedging Instrument Liabilites [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Total mark-to-market derivative liabilities (9,192)   (9,192) (1,928)
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Recurring [Member] | Proprietary Trading Liabilities [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Total mark-to-market derivative liabilities (32)   (32) (21)
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Recurring [Member] | Effects of Netting and Allocation of Collateral Liabilites [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Total mark-to-market derivative liabilities 9,159   9,159 1,918
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Recurring [Member] | Nuclear Decommissioning Trust Fund Investments [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 3,148   3,148 3,981
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Recurring [Member] | Cash Equivalents NDT [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 135   135 95
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Recurring [Member] | Equity Securities Nuclear Decommissioning Trust Fund [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 1,717   1,717 2,077
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Recurring [Member] | Fixed Income Securities [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 1,296   1,296 1,809
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Recurring [Member] | Corporate Debt Securities [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 1,155   1,155 1,485
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Recurring [Member] | US Treasury and Government [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 29   29 126
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Recurring [Member] | Debt Security, Government, Non-US [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 54   54 56
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Recurring [Member] | State and municipal debt [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 29   29 101
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Recurring [Member] | Other Fixed Income [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 29   29 41
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Recurring [Member] | Middle Market Lending [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 0   0 0
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Recurring [Member] | Private Equity Funds [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 0   0 0
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Recurring [Member] | Real Estate Funds [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 0   0 0
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Recurring [Member] | Rabbi Trust Investments [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 33   33 28
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Recurring [Member] | Cash Equivalents [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 0   0 0
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Recurring [Member] | Mutual Funds [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 0   0 0
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Recurring [Member] | Fixed Income Investments [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 0   0 0
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Recurring [Member] | 6311 Life Insurance [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 33   33 28
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Recurring [Member] | Equity Securities [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 0   0 0
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Recurring [Member] | Commodity derivative assets [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Derivative Asset 820   820 334
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Recurring [Member] | Economic Hedges [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Derivative Asset 10,633   10,633 1,914
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Recurring [Member] | Proprietary Trading [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Derivative Asset 56   56 17
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Recurring [Member] | Effects of netting and allocation of collateral [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Derivative Asset (9,869)   (9,869) (1,597)
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Recurring [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Cash equivalents 0   0 0
DPP consideration 0   0 0
Assets, Fair Value Disclosure 762   762 1,218
Deferred Compensation Liability, Current and Noncurrent 0   0 0
Total Liabilities (2,148)   (2,148) (291)
Fair Value, Net Asset (Liability) (1,386)   (1,386) 927
Collateral received from counterparties, net of collateral paid to counterparties (590)   (590) 162
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Recurring [Member] | Commodity Derivative Liabilites [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Total mark-to-market derivative liabilities (2,148)   (2,148) (291)
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Recurring [Member] | Economic Hedging Instrument Liabilites [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Total mark-to-market derivative liabilities (8,340)   (8,340) (1,354)
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Recurring [Member] | Proprietary Trading Liabilities [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Total mark-to-market derivative liabilities (26)   (26) (4)
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Recurring [Member] | Effects of Netting and Allocation of Collateral Liabilites [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Total mark-to-market derivative liabilities 6,218   6,218 1,067
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Recurring [Member] | Nuclear Decommissioning Trust Fund Investments [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 475   475 497
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Recurring [Member] | Cash Equivalents NDT [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 0   0 0
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Recurring [Member] | Equity Securities Nuclear Decommissioning Trust Fund [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 1   1 0
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Recurring [Member] | Fixed Income Securities [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 287   287 285
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Recurring [Member] | Corporate Debt Securities [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 287   287 285
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Recurring [Member] | US Treasury and Government [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 0   0 0
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Recurring [Member] | Debt Security, Government, Non-US [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 0   0 0
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Recurring [Member] | State and municipal debt [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 0   0 0
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Recurring [Member] | Other Fixed Income [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 0   0 0
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Recurring [Member] | Middle Market Lending [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 187   187 212
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Recurring [Member] | Private Equity Funds [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 0   0 0
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Recurring [Member] | Real Estate Funds [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 0   0 0
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Recurring [Member] | Rabbi Trust Investments [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 0   0 0
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Recurring [Member] | Cash Equivalents [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 0   0 0
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Recurring [Member] | Mutual Funds [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 0   0 0
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Recurring [Member] | Fixed Income Investments [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 0   0 0
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Recurring [Member] | 6311 Life Insurance [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 0   0 0
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Recurring [Member] | Equity Securities [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 0   0 0
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Recurring [Member] | Commodity derivative assets [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Derivative Asset 287   287 721
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Recurring [Member] | Economic Hedges [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Derivative Asset 7,083   7,083 1,599
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Recurring [Member] | Proprietary Trading [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Derivative Asset 12   12 27
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Recurring [Member] | Effects of netting and allocation of collateral [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Derivative Asset (6,808)   (6,808) (905)
Exelon Generation Co L L C [Member] | Fair Value Measured at Net Asset Value Per Share [Member] | Fair Value, Recurring [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Cash equivalents 0   0 0
DPP consideration 0   0 0
Assets, Fair Value Disclosure 4,866   4,866 4,335
Deferred Compensation Liability, Current and Noncurrent 0   0 0
Total Liabilities 0   0 0
Fair Value, Net Asset (Liability) 4,866   4,866 4,335
Exelon Generation Co L L C [Member] | Fair Value Measured at Net Asset Value Per Share [Member] | Fair Value, Recurring [Member] | Commodity Derivative Liabilites [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Total mark-to-market derivative liabilities 0   0 0
Exelon Generation Co L L C [Member] | Fair Value Measured at Net Asset Value Per Share [Member] | Fair Value, Recurring [Member] | Economic Hedging Instrument Liabilites [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Total mark-to-market derivative liabilities 0   0 0
Exelon Generation Co L L C [Member] | Fair Value Measured at Net Asset Value Per Share [Member] | Fair Value, Recurring [Member] | Proprietary Trading Liabilities [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Total mark-to-market derivative liabilities 0   0 0
Exelon Generation Co L L C [Member] | Fair Value Measured at Net Asset Value Per Share [Member] | Fair Value, Recurring [Member] | Effects of Netting and Allocation of Collateral Liabilites [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Total mark-to-market derivative liabilities 0   0 0
Exelon Generation Co L L C [Member] | Fair Value Measured at Net Asset Value Per Share [Member] | Fair Value, Recurring [Member] | Nuclear Decommissioning Trust Fund Investments [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 4,866   4,866 4,335
Exelon Generation Co L L C [Member] | Fair Value Measured at Net Asset Value Per Share [Member] | Fair Value, Recurring [Member] | Cash Equivalents NDT [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 0   0 0
Exelon Generation Co L L C [Member] | Fair Value Measured at Net Asset Value Per Share [Member] | Fair Value, Recurring [Member] | Equity Securities Nuclear Decommissioning Trust Fund [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 1,559   1,559 1,562
Exelon Generation Co L L C [Member] | Fair Value Measured at Net Asset Value Per Share [Member] | Fair Value, Recurring [Member] | Fixed Income Securities [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 1,259   1,259 961
Exelon Generation Co L L C [Member] | Fair Value Measured at Net Asset Value Per Share [Member] | Fair Value, Recurring [Member] | Corporate Debt Securities [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 0   0 0
Exelon Generation Co L L C [Member] | Fair Value Measured at Net Asset Value Per Share [Member] | Fair Value, Recurring [Member] | US Treasury and Government [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 0   0 0
Exelon Generation Co L L C [Member] | Fair Value Measured at Net Asset Value Per Share [Member] | Fair Value, Recurring [Member] | Debt Security, Government, Non-US [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 0   0 0
Exelon Generation Co L L C [Member] | Fair Value Measured at Net Asset Value Per Share [Member] | Fair Value, Recurring [Member] | State and municipal debt [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 0   0 0
Exelon Generation Co L L C [Member] | Fair Value Measured at Net Asset Value Per Share [Member] | Fair Value, Recurring [Member] | Other Fixed Income [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 1,259   1,259 961
Exelon Generation Co L L C [Member] | Fair Value Measured at Net Asset Value Per Share [Member] | Fair Value, Recurring [Member] | Middle Market Lending [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 592   592 629
Exelon Generation Co L L C [Member] | Fair Value Measured at Net Asset Value Per Share [Member] | Fair Value, Recurring [Member] | Private Equity Funds [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 654   654 504
Exelon Generation Co L L C [Member] | Fair Value Measured at Net Asset Value Per Share [Member] | Fair Value, Recurring [Member] | Real Estate Funds [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 802   802 679
Exelon Generation Co L L C [Member] | Fair Value Measured at Net Asset Value Per Share [Member] | Fair Value, Recurring [Member] | Rabbi Trust Investments [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 0   0 0
Exelon Generation Co L L C [Member] | Fair Value Measured at Net Asset Value Per Share [Member] | Fair Value, Recurring [Member] | Cash Equivalents [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 0   0 0
Exelon Generation Co L L C [Member] | Fair Value Measured at Net Asset Value Per Share [Member] | Fair Value, Recurring [Member] | Mutual Funds [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 0   0 0
Exelon Generation Co L L C [Member] | Fair Value Measured at Net Asset Value Per Share [Member] | Fair Value, Recurring [Member] | Fixed Income Investments [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 0   0 0
Exelon Generation Co L L C [Member] | Fair Value Measured at Net Asset Value Per Share [Member] | Fair Value, Recurring [Member] | 6311 Life Insurance [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 0   0 0
Exelon Generation Co L L C [Member] | Fair Value Measured at Net Asset Value Per Share [Member] | Fair Value, Recurring [Member] | Equity Securities [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 0   0 0
Exelon Generation Co L L C [Member] | Fair Value Measured at Net Asset Value Per Share [Member] | Fair Value, Recurring [Member] | Commodity derivative assets [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Derivative Asset 0   0 0
Exelon Generation Co L L C [Member] | Fair Value Measured at Net Asset Value Per Share [Member] | Fair Value, Recurring [Member] | Economic Hedges [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Derivative Asset 0   0 0
Exelon Generation Co L L C [Member] | Fair Value Measured at Net Asset Value Per Share [Member] | Fair Value, Recurring [Member] | Proprietary Trading [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Derivative Asset 0   0 0
Exelon Generation Co L L C [Member] | Fair Value Measured at Net Asset Value Per Share [Member] | Fair Value, Recurring [Member] | Effects of netting and allocation of collateral [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Derivative Asset 0   0 0
Commonwealth Edison Co [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Mark-to-market derivative liabilities (current liabilities) 5   5 33
Derivative Liability, Noncurrent 209   209 268
Unrealized Gain (Loss) on Investments 0   0  
Commonwealth Edison Co [Member] | Other Assets [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Cash equivalents       43
Commonwealth Edison Co [Member] | Fair Value, Recurring [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Cash equivalents 309   309 285
Assets, Fair Value Disclosure 309   309 285
Total mark-to-market derivative liabilities (214)   (214) (301)
Deferred Compensation Liability, Current and Noncurrent (9)   (9) (8)
Total Liabilities (223)   (223) (309)
Fair Value, Net Asset (Liability) 86   86 (24)
Mark-to-market derivative liabilities (current liabilities) 5   5 33
Derivative Liability, Noncurrent 209   209 268
Commonwealth Edison Co [Member] | Fair Value, Recurring [Member] | Cash and Cash Equivalents [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Cash equivalents 145   145 83
Commonwealth Edison Co [Member] | Fair Value, Recurring [Member] | Restricted cash member [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Cash equivalents 107   107 37
Commonwealth Edison Co [Member] | Fair Value, Recurring [Member] | Other Assets [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Cash equivalents 44   44 44
Commonwealth Edison Co [Member] | Fair Value, Recurring [Member] | Rabbi Trust Investments [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 0   0 0
Commonwealth Edison Co [Member] | Fair Value, Recurring [Member] | Mutual Funds [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 0   0 0
Commonwealth Edison Co [Member] | Fair Value, Recurring [Member] | 6311 Life Insurance [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 0   0 0
Commonwealth Edison Co [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Recurring [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Cash equivalents 309   309 285
Assets, Fair Value Disclosure 309   309 285
Total mark-to-market derivative liabilities 0   0 0
Deferred Compensation Liability, Current and Noncurrent 0   0 0
Total Liabilities 0   0 0
Fair Value, Net Asset (Liability) 309   309 285
Commonwealth Edison Co [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Recurring [Member] | Rabbi Trust Investments [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 0   0 0
Commonwealth Edison Co [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Recurring [Member] | Mutual Funds [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 0   0 0
Commonwealth Edison Co [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Recurring [Member] | 6311 Life Insurance [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 0   0 0
Commonwealth Edison Co [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Recurring [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Cash equivalents 0   0 0
Assets, Fair Value Disclosure 0   0 0
Total mark-to-market derivative liabilities 0   0 0
Deferred Compensation Liability, Current and Noncurrent (9)   (9) (8)
Total Liabilities (9)   (9) (8)
Fair Value, Net Asset (Liability) (9)   (9) (8)
Commonwealth Edison Co [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Recurring [Member] | Rabbi Trust Investments [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 0   0 0
Commonwealth Edison Co [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Recurring [Member] | Mutual Funds [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 0   0 0
Commonwealth Edison Co [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Recurring [Member] | 6311 Life Insurance [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 0   0 0
Commonwealth Edison Co [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Recurring [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Cash equivalents 0   0 0
Assets, Fair Value Disclosure 0   0 0
Total mark-to-market derivative liabilities (214)   (214) (301)
Deferred Compensation Liability, Current and Noncurrent 0   0 0
Total Liabilities (214)   (214) (301)
Fair Value, Net Asset (Liability) (214)   (214) (301)
Commonwealth Edison Co [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Recurring [Member] | Rabbi Trust Investments [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 0   0 0
Commonwealth Edison Co [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Recurring [Member] | Mutual Funds [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 0   0 0
Commonwealth Edison Co [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Recurring [Member] | 6311 Life Insurance [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 0   0 0
PECO Energy Co [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Unrealized Gain (Loss) on Investments 0   0  
PECO Energy Co [Member] | Fair Value, Recurring [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Cash equivalents 247   247 8
Assets, Fair Value Disclosure 272   272 30
Total mark-to-market derivative liabilities 0   0 0
Deferred Compensation Liability, Current and Noncurrent (8)   (8) (9)
Total Liabilities (8)   (8) (9)
Fair Value, Net Asset (Liability) 264   264 21
PECO Energy Co [Member] | Fair Value, Recurring [Member] | Cash and Cash Equivalents [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Cash equivalents 105   105 18
PECO Energy Co [Member] | Fair Value, Recurring [Member] | Rabbi Trust Investments [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 25   25 22
PECO Energy Co [Member] | Fair Value, Recurring [Member] | Mutual Funds [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 10   10 9
PECO Energy Co [Member] | Fair Value, Recurring [Member] | 6311 Life Insurance [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 15   15 13
PECO Energy Co [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Recurring [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Cash equivalents 247   247 8
Assets, Fair Value Disclosure 257   257 17
Total mark-to-market derivative liabilities 0   0 0
Deferred Compensation Liability, Current and Noncurrent 0   0 0
Total Liabilities 0   0 0
Fair Value, Net Asset (Liability) 257   257 17
PECO Energy Co [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Recurring [Member] | Rabbi Trust Investments [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 10   10 9
PECO Energy Co [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Recurring [Member] | Mutual Funds [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 10   10 9
PECO Energy Co [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Recurring [Member] | 6311 Life Insurance [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 0   0 0
PECO Energy Co [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Recurring [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Cash equivalents 0   0 0
Assets, Fair Value Disclosure 15   15 13
Total mark-to-market derivative liabilities 0   0 0
Deferred Compensation Liability, Current and Noncurrent (8)   (8) (9)
Total Liabilities (8)   (8) (9)
Fair Value, Net Asset (Liability) 7   7 4
PECO Energy Co [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Recurring [Member] | Rabbi Trust Investments [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 15   15 13
PECO Energy Co [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Recurring [Member] | Mutual Funds [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 0   0 0
PECO Energy Co [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Recurring [Member] | 6311 Life Insurance [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 15   15 13
PECO Energy Co [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Recurring [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Cash equivalents 0   0 0
Assets, Fair Value Disclosure 0   0 0
Total mark-to-market derivative liabilities 0   0 0
Deferred Compensation Liability, Current and Noncurrent 0   0 0
Total Liabilities 0   0 0
Fair Value, Net Asset (Liability) 0   0 0
PECO Energy Co [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Recurring [Member] | Rabbi Trust Investments [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 0   0 0
PECO Energy Co [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Recurring [Member] | Mutual Funds [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 0   0 0
PECO Energy Co [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Recurring [Member] | 6311 Life Insurance [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 0   0 0
Baltimore Gas and Electric Company [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Unrealized Gain (Loss) on Investments 0   0  
Baltimore Gas and Electric Company [Member] | Fair Value, Recurring [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Cash equivalents 169   169 120
Assets, Fair Value Disclosure 183   183 130
Total mark-to-market derivative liabilities 0   0 0
Deferred Compensation Liability, Current and Noncurrent (6)   (6) (5)
Total Liabilities (6)   (6) (5)
Fair Value, Net Asset (Liability) 177   177 125
Baltimore Gas and Electric Company [Member] | Fair Value, Recurring [Member] | Cash and Cash Equivalents [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Cash equivalents 56   56 24
Baltimore Gas and Electric Company [Member] | Fair Value, Recurring [Member] | Restricted cash member [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Cash equivalents 27   27 1
Baltimore Gas and Electric Company [Member] | Fair Value, Recurring [Member] | Rabbi Trust Investments [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 14   14 10
Baltimore Gas and Electric Company [Member] | Fair Value, Recurring [Member] | Mutual Funds [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 14   14 10
Baltimore Gas and Electric Company [Member] | Fair Value, Recurring [Member] | 6311 Life Insurance [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 0   0 0
Baltimore Gas and Electric Company [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Recurring [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Cash equivalents 169   169 120
Assets, Fair Value Disclosure 183   183 130
Total mark-to-market derivative liabilities 0   0 0
Deferred Compensation Liability, Current and Noncurrent 0   0 0
Total Liabilities 0   0 0
Fair Value, Net Asset (Liability) 183   183 130
Baltimore Gas and Electric Company [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Recurring [Member] | Rabbi Trust Investments [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 14   14 10
Baltimore Gas and Electric Company [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Recurring [Member] | Mutual Funds [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 14   14 10
Baltimore Gas and Electric Company [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Recurring [Member] | 6311 Life Insurance [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 0   0 0
Baltimore Gas and Electric Company [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Recurring [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Cash equivalents 0   0 0
Assets, Fair Value Disclosure 0   0 0
Total mark-to-market derivative liabilities 0   0 0
Deferred Compensation Liability, Current and Noncurrent (6)   (6) (5)
Total Liabilities (6)   (6) (5)
Fair Value, Net Asset (Liability) (6)   (6) (5)
Baltimore Gas and Electric Company [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Recurring [Member] | Rabbi Trust Investments [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 0   0 0
Baltimore Gas and Electric Company [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Recurring [Member] | Mutual Funds [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 0   0 0
Baltimore Gas and Electric Company [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Recurring [Member] | 6311 Life Insurance [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 0   0 0
Baltimore Gas and Electric Company [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Recurring [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Cash equivalents 0   0 0
Assets, Fair Value Disclosure 0   0 0
Total mark-to-market derivative liabilities 0   0 0
Deferred Compensation Liability, Current and Noncurrent 0   0 0
Total Liabilities 0   0 0
Fair Value, Net Asset (Liability) 0   0 0
Baltimore Gas and Electric Company [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Recurring [Member] | Rabbi Trust Investments [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 0   0 0
Baltimore Gas and Electric Company [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Recurring [Member] | Mutual Funds [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 0   0 0
Baltimore Gas and Electric Company [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Recurring [Member] | 6311 Life Insurance [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 0   0 0
Pepco Holdings LLC [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Unrealized Gain (Loss) on Investments 0   0  
Pepco Holdings LLC [Member] | Fair Value, Recurring [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Cash equivalents 100   100 86
Assets, Fair Value Disclosure 244   244 226
Deferred Compensation Liability, Current and Noncurrent (19)   (19) (17)
Total Liabilities (19)   (19) (17)
Fair Value, Net Asset (Liability) 225   225 209
Pepco Holdings LLC [Member] | Fair Value, Recurring [Member] | Cash and Cash Equivalents [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Cash equivalents 57   57 74
Pepco Holdings LLC [Member] | Fair Value, Recurring [Member] | Restricted cash member [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Cash equivalents 5   5 0
Pepco Holdings LLC [Member] | Fair Value, Recurring [Member] | Other Assets [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Cash equivalents 9   9 10
Pepco Holdings LLC [Member] | Fair Value, Recurring [Member] | Rabbi Trust Investments [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 144   144 140
Pepco Holdings LLC [Member] | Fair Value, Recurring [Member] | Cash Equivalents [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 59   59 55
Pepco Holdings LLC [Member] | Fair Value, Recurring [Member] | Mutual Funds [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 14   14 14
Pepco Holdings LLC [Member] | Fair Value, Recurring [Member] | Fixed Income Investments [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 10   10 11
Pepco Holdings LLC [Member] | Fair Value, Recurring [Member] | 6311 Life Insurance [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 61   61 60
Pepco Holdings LLC [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Recurring [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Cash equivalents 100   100 86
Assets, Fair Value Disclosure 173   173 155
Deferred Compensation Liability, Current and Noncurrent 0   0 0
Total Liabilities 0   0 0
Fair Value, Net Asset (Liability) 173   173 155
Pepco Holdings LLC [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Recurring [Member] | Rabbi Trust Investments [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 73   73 69
Pepco Holdings LLC [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Recurring [Member] | Cash Equivalents [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 59   59 55
Pepco Holdings LLC [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Recurring [Member] | Mutual Funds [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 14   14 14
Pepco Holdings LLC [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Recurring [Member] | Fixed Income Investments [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 0   0 0
Pepco Holdings LLC [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Recurring [Member] | 6311 Life Insurance [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 0   0 0
Pepco Holdings LLC [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Recurring [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Cash equivalents 0   0 0
Assets, Fair Value Disclosure 37   37 37
Deferred Compensation Liability, Current and Noncurrent (19)   (19) (17)
Total Liabilities (19)   (19) (17)
Fair Value, Net Asset (Liability) 18   18 20
Pepco Holdings LLC [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Recurring [Member] | Rabbi Trust Investments [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 37   37 37
Pepco Holdings LLC [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Recurring [Member] | Cash Equivalents [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 0   0 0
Pepco Holdings LLC [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Recurring [Member] | Mutual Funds [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 0   0 0
Pepco Holdings LLC [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Recurring [Member] | Fixed Income Investments [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 10   10 11
Pepco Holdings LLC [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Recurring [Member] | 6311 Life Insurance [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 27   27 26
Pepco Holdings LLC [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Recurring [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Cash equivalents 0   0 0
Assets, Fair Value Disclosure 34   34 34
Deferred Compensation Liability, Current and Noncurrent 0   0 0
Total Liabilities 0   0 0
Fair Value, Net Asset (Liability) 34   34 34
Pepco Holdings LLC [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Recurring [Member] | Rabbi Trust Investments [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 34   34 34
Pepco Holdings LLC [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Recurring [Member] | Cash Equivalents [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 0   0 0
Pepco Holdings LLC [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Recurring [Member] | Mutual Funds [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 0   0 0
Pepco Holdings LLC [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Recurring [Member] | Fixed Income Investments [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 0   0 0
Pepco Holdings LLC [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Recurring [Member] | 6311 Life Insurance [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 34   34 34
Potomac Electric Power Company [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Unrealized Gain (Loss) on Investments 0   0  
Potomac Electric Power Company [Member] | Fair Value, Recurring [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Cash equivalents 36   36 35
Assets, Fair Value Disclosure 155   155 150
Deferred Compensation Liability, Current and Noncurrent (2)   (2) (2)
Total Liabilities (2)   (2) (2)
Fair Value, Net Asset (Liability) 153   153 148
Potomac Electric Power Company [Member] | Fair Value, Recurring [Member] | Cash and Cash Equivalents [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Cash equivalents 19   19 30
Potomac Electric Power Company [Member] | Fair Value, Recurring [Member] | Restricted cash member [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Cash equivalents 5   5 0
Potomac Electric Power Company [Member] | Fair Value, Recurring [Member] | Rabbi Trust Investments [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 119   119 115
Potomac Electric Power Company [Member] | Fair Value, Recurring [Member] | Cash Equivalents [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 58   58 53
Potomac Electric Power Company [Member] | Fair Value, Recurring [Member] | Fixed Income Investments [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 0   0 2
Potomac Electric Power Company [Member] | Fair Value, Recurring [Member] | 6311 Life Insurance [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 61   61 60
Potomac Electric Power Company [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Recurring [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Cash equivalents 36   36 35
Assets, Fair Value Disclosure 94   94 88
Deferred Compensation Liability, Current and Noncurrent 0   0 0
Total Liabilities 0   0 0
Fair Value, Net Asset (Liability) 94   94 88
Potomac Electric Power Company [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Recurring [Member] | Rabbi Trust Investments [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 58   58 53
Potomac Electric Power Company [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Recurring [Member] | Cash Equivalents [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 58   58 53
Potomac Electric Power Company [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Recurring [Member] | Fixed Income Investments [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 0   0 0
Potomac Electric Power Company [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Recurring [Member] | 6311 Life Insurance [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 0   0 0
Potomac Electric Power Company [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Recurring [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Cash equivalents 0   0 0
Assets, Fair Value Disclosure 27   27 28
Deferred Compensation Liability, Current and Noncurrent (2)   (2) (2)
Total Liabilities (2)   (2) (2)
Fair Value, Net Asset (Liability) 25   25 26
Potomac Electric Power Company [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Recurring [Member] | Rabbi Trust Investments [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 27   27 28
Potomac Electric Power Company [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Recurring [Member] | Cash Equivalents [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 0   0 0
Potomac Electric Power Company [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Recurring [Member] | Fixed Income Investments [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 0   0 2
Potomac Electric Power Company [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Recurring [Member] | 6311 Life Insurance [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 27   27 26
Potomac Electric Power Company [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Recurring [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Cash equivalents 0   0 0
Assets, Fair Value Disclosure 34   34 34
Deferred Compensation Liability, Current and Noncurrent 0   0 0
Total Liabilities 0   0 0
Fair Value, Net Asset (Liability) 34   34 34
Potomac Electric Power Company [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Recurring [Member] | Rabbi Trust Investments [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 34   34 34
Potomac Electric Power Company [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Recurring [Member] | Cash Equivalents [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 0   0 0
Potomac Electric Power Company [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Recurring [Member] | Fixed Income Investments [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 0   0 0
Potomac Electric Power Company [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Recurring [Member] | 6311 Life Insurance [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 34   34 34
Delmarva Power and Light Company [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Unrealized Gain (Loss) on Investments 0   0  
Delmarva Power and Light Company [Member] | Fair Value, Recurring [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Cash equivalents 26   26 0
Assets, Fair Value Disclosure 26   26 0
Deferred Compensation Liability, Current and Noncurrent 0   0 0
Total Liabilities 0   0 0
Fair Value, Net Asset (Liability) 26   26 0
Delmarva Power and Light Company [Member] | Fair Value, Recurring [Member] | Cash and Cash Equivalents [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Cash equivalents 13   13 15
Delmarva Power and Light Company [Member] | Fair Value, Recurring [Member] | Rabbi Trust Investments [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 0   0 0
Delmarva Power and Light Company [Member] | Fair Value, Recurring [Member] | Cash Equivalents [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 0   0 0
Delmarva Power and Light Company [Member] | Fair Value, Recurring [Member] | Fixed Income Investments [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 0   0 0
Delmarva Power and Light Company [Member] | Fair Value, Recurring [Member] | 6311 Life Insurance [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 0   0 0
Delmarva Power and Light Company [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Recurring [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Cash equivalents 26   26 0
Assets, Fair Value Disclosure 26   26 0
Deferred Compensation Liability, Current and Noncurrent 0   0 0
Total Liabilities 0   0 0
Fair Value, Net Asset (Liability) 26   26 0
Delmarva Power and Light Company [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Recurring [Member] | Rabbi Trust Investments [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 0   0 0
Delmarva Power and Light Company [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Recurring [Member] | Cash Equivalents [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 0   0 0
Delmarva Power and Light Company [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Recurring [Member] | Fixed Income Investments [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 0   0 0
Delmarva Power and Light Company [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Recurring [Member] | 6311 Life Insurance [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 0   0 0
Delmarva Power and Light Company [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Recurring [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Cash equivalents 0   0 0
Assets, Fair Value Disclosure 0   0 0
Deferred Compensation Liability, Current and Noncurrent 0   0 0
Total Liabilities 0   0 0
Fair Value, Net Asset (Liability) 0   0 0
Delmarva Power and Light Company [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Recurring [Member] | Rabbi Trust Investments [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 0   0 0
Delmarva Power and Light Company [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Recurring [Member] | Cash Equivalents [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 0   0 0
Delmarva Power and Light Company [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Recurring [Member] | Fixed Income Investments [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 0   0 0
Delmarva Power and Light Company [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Recurring [Member] | 6311 Life Insurance [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 0   0 0
Delmarva Power and Light Company [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Recurring [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Cash equivalents 0   0 0
Assets, Fair Value Disclosure 0   0 0
Deferred Compensation Liability, Current and Noncurrent 0   0 0
Total Liabilities 0   0 0
Fair Value, Net Asset (Liability) 0   0 0
Delmarva Power and Light Company [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Recurring [Member] | Rabbi Trust Investments [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 0   0 0
Delmarva Power and Light Company [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Recurring [Member] | Cash Equivalents [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 0   0 0
Delmarva Power and Light Company [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Recurring [Member] | Fixed Income Investments [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 0   0 0
Delmarva Power and Light Company [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Recurring [Member] | 6311 Life Insurance [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 0   0 0
Atlantic City Electric Company [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Unrealized Gain (Loss) on Investments 0   0  
Atlantic City Electric Company [Member] | Fair Value, Recurring [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Cash equivalents 14   14 13
Assets, Fair Value Disclosure 14   14 13
Deferred Compensation Liability, Current and Noncurrent 0   0 0
Total Liabilities 0   0 0
Fair Value, Net Asset (Liability) 14   14 13
Atlantic City Electric Company [Member] | Fair Value, Recurring [Member] | Cash and Cash Equivalents [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Cash equivalents 16   16 17
Atlantic City Electric Company [Member] | Fair Value, Recurring [Member] | Other Assets [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Cash equivalents 9   9 10
Atlantic City Electric Company [Member] | Fair Value, Recurring [Member] | Rabbi Trust Investments [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 0   0 0
Atlantic City Electric Company [Member] | Fair Value, Recurring [Member] | Cash Equivalents [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 0   0 0
Atlantic City Electric Company [Member] | Fair Value, Recurring [Member] | Fixed Income Investments [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 0   0 0
Atlantic City Electric Company [Member] | Fair Value, Recurring [Member] | 6311 Life Insurance [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 0   0 0
Atlantic City Electric Company [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Recurring [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Cash equivalents 14   14 13
Assets, Fair Value Disclosure 14   14 13
Deferred Compensation Liability, Current and Noncurrent 0   0 0
Total Liabilities 0   0 0
Fair Value, Net Asset (Liability) 14   14 13
Atlantic City Electric Company [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Recurring [Member] | Rabbi Trust Investments [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 0   0 0
Atlantic City Electric Company [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Recurring [Member] | Cash Equivalents [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 0   0 0
Atlantic City Electric Company [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Recurring [Member] | Fixed Income Investments [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 0   0 0
Atlantic City Electric Company [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Recurring [Member] | 6311 Life Insurance [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 0   0 0
Atlantic City Electric Company [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Recurring [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Cash equivalents 0   0 0
Assets, Fair Value Disclosure 0   0 0
Deferred Compensation Liability, Current and Noncurrent 0   0 0
Total Liabilities 0   0 0
Fair Value, Net Asset (Liability) 0   0 0
Atlantic City Electric Company [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Recurring [Member] | Rabbi Trust Investments [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 0   0 0
Atlantic City Electric Company [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Recurring [Member] | Cash Equivalents [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 0   0 0
Atlantic City Electric Company [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Recurring [Member] | Fixed Income Investments [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 0   0 0
Atlantic City Electric Company [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Recurring [Member] | 6311 Life Insurance [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 0   0 0
Atlantic City Electric Company [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Recurring [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Cash equivalents 0   0 0
Assets, Fair Value Disclosure 0   0 0
Deferred Compensation Liability, Current and Noncurrent 0   0 0
Total Liabilities 0   0 0
Fair Value, Net Asset (Liability) 0   0 0
Atlantic City Electric Company [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Recurring [Member] | Rabbi Trust Investments [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 0   0 0
Atlantic City Electric Company [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Recurring [Member] | Cash Equivalents [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 0   0 0
Atlantic City Electric Company [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Recurring [Member] | Fixed Income Investments [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 0   0 0
Atlantic City Electric Company [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Recurring [Member] | 6311 Life Insurance [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Investments, Fair Value Disclosure 0   0 0
Exelon Generation Co LLC Affiliate [Member] | Fair Value, Recurring [Member] | Nuclear Decommissioning Trust Fund Investments [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Financial Instruments Sold, Not yet Purchased, Corporate Debt (50)   (50) (62)
Maturity Less than 30 Days [Member] | Fair Value, Recurring [Member] | Nuclear Decommissioning Trust Fund Investments [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Derivative, Collateral, Right to Reclaim Cash 109   109 116
Maturity Less than 30 Days [Member] | Exelon Generation Co L L C [Member] | Fair Value, Recurring [Member] | Nuclear Decommissioning Trust Fund Investments [Member]        
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]        
Derivative, Collateral, Right to Reclaim Cash $ 109   $ 109 $ 116