Fair Value of Financial Assets and Liabilities - Fair Value Measurements of Assets and Liabilities, Recurring and Nonrecurring (Details) - USD ($) $ in Millions	Sep. 30, 2020	Dec. 31, 2019
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Mark-to-market derivative liabilities (current liabilities)	$ 177	$ 247
Derivative Liability, Noncurrent	396	393
Derivative Instruments Not Designated as Hedging Instruments, Asset, at Fair Value	1	2
Derivative Asset, Notional Amount	658	724
Margin Deposit Assets	34	511
Derivative, Notional Amount	153	99
Cash and Cash Equivalents [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Cash equivalents	677	373
Restricted cash member [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Cash equivalents	116	110
Other Assets [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Cash equivalents	137	177
Nuclear Decommissioning Trust Fund Investments [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Net assets (liabilities) excluded from nuclear decommissioning trust fund investments	208	147
Fair Value, Recurring [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Cash equivalents	1,687	639
Deferred purchase price	732
Assets, Fair Value Disclosure	17,303	15,584
Deferred Compensation Liability, Current and Noncurrent	(135)	(147)
Total Liabilities	(681)	(763)
Fair Value, Net Asset (Liability)	16,622	14,821
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	(546)	(616)
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	(4,031)	(5,154)
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	(52)	(49)
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	3,537	4,587
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	13,755	13,500
Fair Value, Recurring [Member] | Cash Equivalents NDT [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	404	452
Fair Value, Recurring [Member] | Equity Securities [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	6,509	6,494
Fair Value, Recurring [Member] | Fixed Income Securities [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	4,982	4,783
Fair Value, Recurring [Member] | Corporate Debt Securities [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	1,796	1,726
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	1,980	1,939
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	52	42
Fair Value, Recurring [Member] | State and municipal debt [Domain]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	104	90
Fair Value, Recurring [Member] | Other Fixed Income [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	1,050	986
Fair Value, Recurring [Member] | Middle Market Lending [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	771	762
Fair Value, Recurring [Member] | Private Equity Funds [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	439	402
Fair Value, Recurring [Member] | Real Estate Funds [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	650	607
Fair Value, Recurring [Member] | Rabbi Trust Investments [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	275	262
Fair Value, Recurring [Member] | Cash Equivalents [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	58	50
Fair Value, Recurring [Member] | Mutual Funds [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	88	81
Fair Value, Recurring [Member] | Fixed Income Investments [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	11	12
Fair Value, Recurring [Member] | 6311 Life Insurance [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	118	119
Fair Value, Recurring [Member] | Commodity Derivative Assets [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Derivative Asset	854	1,183
Fair Value, Recurring [Member] | Economic Hedging Instrument [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Derivative Asset	4,066	4,744
Fair Value, Recurring [Member] | Proprietary Trading [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Derivative Asset	74	97
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	(3,286)	(3,658)
Fair Value, Inputs, Level 1 [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Collateral received from counterparties, net of collateral paid to counterparties	43	163
Fair Value, Inputs, Level 1 [Member] | Fair Value, Recurring [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Cash equivalents	1,687	639
Deferred purchase price	0
Assets, Fair Value Disclosure	7,454	6,156
Deferred Compensation Liability, Current and Noncurrent	0	0
Total Liabilities	(1)	0
Fair Value, Net Asset (Liability)	7,453	6,156
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	(1)	0
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	(700)	(1,071)
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
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	699	1,071
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	5,501	5,526
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	313	365
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	3,345	3,353
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	1,843	1,808
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
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	1,843	1,808
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
Fair Value, Inputs, Level 1 [Member] | Fair Value, Recurring [Member] | State and municipal debt [Domain]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	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	0	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
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
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
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	146	131
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	50
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	88	81
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
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
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	120	(140)
Fair Value, Inputs, Level 1 [Member] | Fair Value, Recurring [Member] | Economic Hedging Instrument [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Derivative Asset	776	768
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
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	(656)	(908)
Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Collateral received from counterparties, net of collateral paid to counterparties	114	551
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
Deferred purchase price	732
Assets, Fair Value Disclosure	4,741	4,061
Deferred Compensation Liability, Current and Noncurrent	(135)	(147)
Total Liabilities	(155)	(322)
Fair Value, Net Asset (Liability)	4,586	3,739
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	(20)	(175)
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	(1,692)	(2,855)
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	(36)	(34)
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	1,708	2,714
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	3,734	3,605
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	91	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	1,794	1,753
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	1,849	1,765
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	1,516	1,469
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	137	131
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	52	42
Fair Value, Inputs, Level 2 [Member] | Fair Value, Recurring [Member] | State and municipal debt [Domain]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	104	90
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	40	33
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
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
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
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	95	90
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
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
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	11	12
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	84	78
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	180	366
Fair Value, Inputs, Level 2 [Member] | Fair Value, Recurring [Member] | Economic Hedging Instrument [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Derivative Asset	1,737	2,491
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	37	37
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	(1,594)	(2,162)
Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Collateral received from counterparties, net of collateral paid to counterparties	94	214
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
Deferred purchase price	0
Assets, Fair Value Disclosure	1,106	1,509
Deferred Compensation Liability, Current and Noncurrent	0	0
Total Liabilities	(525)	(441)
Fair Value, Net Asset (Liability)	581	1,068
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	(525)	(441)
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	(1,639)	(1,228)
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	(16)	(15)
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	1,130	802
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	518	511
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
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
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	280	257
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	280	257
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
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
Fair Value, Inputs, Level 3 [Member] | Fair Value, Recurring [Member] | State and municipal debt [Domain]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	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
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	238	254
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
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
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	41
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
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
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
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	41
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	554	957
Fair Value, Inputs, Level 3 [Member] | Fair Value, Recurring [Member] | Economic Hedging Instrument [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Derivative Asset	1,553	1,485
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	37	60
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	(1,036)	(588)
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
Deferred purchase price	0
Assets, Fair Value Disclosure	4,002	3,858
Deferred Compensation Liability, Current and Noncurrent	0	0
Total Liabilities	0	0
Fair Value, Net Asset (Liability)	4,002	3,858
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
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
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
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
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	4,002	3,858
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
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	1,370	1,388
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	1,010	953
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
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
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
Fair Value Measured at Net Asset Value Per Share [Member] | Fair Value, Recurring [Member] | State and municipal debt [Domain]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	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	1,010	953
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	533	508
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	439	402
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	650	607
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
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
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
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
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
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
Fair Value Measured at Net Asset Value Per Share [Member] | Fair Value, Recurring [Member] | Economic Hedging Instrument [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Derivative Asset	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
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
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	(215)	(307)
Mark-to-market derivative liabilities (current liabilities)	147	215
Derivative Liability, Noncurrent	121	123
Derivative Instruments Not Designated as Hedging Instruments, Asset, at Fair Value	1	2
Derivative Asset, Notional Amount	658	724
Margin Deposit Assets	34	511
Derivative, Notional Amount	153	99
Exelon Generation Co L L C [Member] | Cash and Cash Equivalents [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Cash equivalents	408	177
Exelon Generation Co L L C [Member] | Restricted cash member [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Cash equivalents	45	58
Exelon Generation Co L L C [Member] | Nuclear Decommissioning Trust Fund Investments [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Net assets (liabilities) excluded from nuclear decommissioning trust fund investments	208	147
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	270	214
Deferred purchase price	732
Assets, Fair Value Disclosure	15,670	14,951
Deferred Compensation Liability, Current and Noncurrent	(37)	(41)
Total Liabilities	(279)	(356)
Fair Value, Net Asset (Liability)	15,391	14,595
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	(242)	(315)
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	(3,727)	(4,853)
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	(52)	(49)
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	3,537	4,587
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	13,755	13,500
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	404	452
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	6,509	6,494
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	4,982	4,783
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	1,796	1,726
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	1,980	1,939
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	52	42
Exelon Generation Co L L C [Member] | Fair Value, Recurring [Member] | State and municipal debt [Domain]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	104	90
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	1,050	986
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	771	762
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	439	402
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	650	607
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	59	54
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
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	28	25
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
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	27	25
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	854	1,183
Exelon Generation Co L L C [Member] | Fair Value, Recurring [Member] | Economic Hedging Instrument [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Derivative Asset	4,066	4,744
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	74	97
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	(3,286)	(3,658)
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 1 [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Collateral received from counterparties, net of collateral paid to counterparties	43	163
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	270	214
Deferred purchase price	0
Assets, Fair Value Disclosure	5,923	5,629
Deferred Compensation Liability, Current and Noncurrent	0	0
Total Liabilities	(1)	0
Fair Value, Net Asset (Liability)	5,922	5,629
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	(1)	0
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	(700)	(1,071)
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
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	699	1,071
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	5,501	5,526
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	313	365
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	3,345	3,353
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	1,843	1,808
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
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	1,843	1,808
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
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Recurring [Member] | State and municipal debt [Domain]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	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	0	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
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
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
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	32	29
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
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	28	25
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
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
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	120	(140)
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Recurring [Member] | Economic Hedging Instrument [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Derivative Asset	776	768
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
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	(656)	(908)
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Collateral received from counterparties, net of collateral paid to counterparties	114	551
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
Deferred purchase price	732
Assets, Fair Value Disclosure	4,673	3,996
Deferred Compensation Liability, Current and Noncurrent	(37)	(41)
Total Liabilities	(57)	(216)
Fair Value, Net Asset (Liability)	4,616	3,780
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	(20)	(175)
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	(1,692)	(2,855)
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	(36)	(34)
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	1,708	2,714
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	3,734	3,605
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	91	87
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	1,794	1,753
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	1,849	1,765
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	1,516	1,469
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	137	131
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	52	42
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Recurring [Member] | State and municipal debt [Domain]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	104	90
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	40	33
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
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
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
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	27	25
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
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
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
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	27	25
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	180	366
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Recurring [Member] | Economic Hedging Instrument [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Derivative Asset	1,737	2,491
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	37	37
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	(1,594)	(2,162)
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Collateral received from counterparties, net of collateral paid to counterparties	94	214
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
Deferred purchase price	0
Assets, Fair Value Disclosure	1,072	1,468
Deferred Compensation Liability, Current and Noncurrent	0	0
Total Liabilities	(221)	(140)
Fair Value, Net Asset (Liability)	851	1,328
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	(221)	(140)
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	(1,335)	(927)
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	(16)	(15)
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	1,130	802
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	518	511
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
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
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	280	257
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	280	257
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
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
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Recurring [Member] | State and municipal debt [Domain]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	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
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	238	254
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
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
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
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
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
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
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
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	554	957
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Recurring [Member] | Economic Hedging Instrument [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Derivative Asset	1,553	1,485
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	37	60
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	(1,036)	(588)
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
Deferred purchase price	0
Assets, Fair Value Disclosure	4,002	3,858
Deferred Compensation Liability, Current and Noncurrent	0	0
Total Liabilities	0	0
Fair Value, Net Asset (Liability)	4,002	3,858
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
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
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
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
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	4,002	3,858
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
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	1,370	1,388
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	1,010	953
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
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
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
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 [Domain]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	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	1,010	953
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	533	508
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	439	402
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	650	607
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
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
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
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
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
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
Exelon Generation Co L L C [Member] | Fair Value Measured at Net Asset Value Per Share [Member] | Fair Value, Recurring [Member] | Economic Hedging Instrument [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Derivative Asset	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
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
Commonwealth Edison Co [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Mark-to-market derivative liabilities (current liabilities)	30	32
Derivative Liability, Noncurrent	274	269
Commonwealth Edison Co [Member] | Cash and Cash Equivalents [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Cash equivalents	76	90
Commonwealth Edison Co [Member] | Restricted cash member [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Cash equivalents	36	33
Commonwealth Edison Co [Member] | Other Assets [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Cash equivalents	127	163
Commonwealth Edison Co [Member] | Fair Value, Recurring [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Cash equivalents	396	280
Assets, Fair Value Disclosure	396	280
Total mark-to-market derivative liabilities	(304)	(301)
Deferred Compensation Liability, Current and Noncurrent	(7)	(8)
Total Liabilities	(311)	(309)
Fair Value, Net Asset (Liability)	85	(29)
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
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
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
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	396	280
Assets, Fair Value Disclosure	396	280
Total mark-to-market derivative liabilities	0	0
Deferred Compensation Liability, Current and Noncurrent	0	0
Total Liabilities	0	0
Fair Value, Net Asset (Liability)	396	280
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
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
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
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
Assets, Fair Value Disclosure	0	0
Total mark-to-market derivative liabilities	0	0
Deferred Compensation Liability, Current and Noncurrent	(7)	(8)
Total Liabilities	(7)	(8)
Fair Value, Net Asset (Liability)	(7)	(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
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
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
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
Assets, Fair Value Disclosure	0	0
Total mark-to-market derivative liabilities	(304)	(301)
Deferred Compensation Liability, Current and Noncurrent	0	0
Total Liabilities	(304)	(301)
Fair Value, Net Asset (Liability)	(304)	(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
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
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
PECO Energy Co [Member] | Cash and Cash Equivalents [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Cash equivalents	65	12
PECO Energy Co [Member] | Fair Value, Recurring [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Cash equivalents	184	15
Assets, Fair Value Disclosure	206	34
Total mark-to-market derivative liabilities	0	0
Deferred Compensation Liability, Current and Noncurrent	(8)	(9)
Total Liabilities	(8)	(9)
Fair Value, Net Asset (Liability)	198	25
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	22	19
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	9	8
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	13	11
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	184	15
Assets, Fair Value Disclosure	193	23
Total mark-to-market derivative liabilities	0	0
Deferred Compensation Liability, Current and Noncurrent	0	0
Total Liabilities	0	0
Fair Value, Net Asset (Liability)	193	23
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	9	8
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	9	8
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
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
Assets, Fair Value Disclosure	13	11
Total mark-to-market derivative liabilities	0	0
Deferred Compensation Liability, Current and Noncurrent	(8)	(9)
Total Liabilities	(8)	(9)
Fair Value, Net Asset (Liability)	5	2
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	13	11
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
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	13	11
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
Assets, Fair Value Disclosure	0	0
Total mark-to-market derivative liabilities	0	0
Deferred Compensation Liability, Current and Noncurrent	0	0
Total Liabilities	0	0
Fair Value, Net Asset (Liability)	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
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
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
Baltimore Gas and Electric Company [Member] | Cash and Cash Equivalents [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Cash equivalents	28	24
Baltimore Gas and Electric Company [Member] | Restricted cash member [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Cash equivalents	1	1
Baltimore Gas and Electric Company [Member] | Fair Value, Recurring [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Cash equivalents	298	0
Assets, Fair Value Disclosure	307	8
Total mark-to-market derivative liabilities	0	0
Deferred Compensation Liability, Current and Noncurrent	(5)	(5)
Total Liabilities	(5)	(5)
Fair Value, Net Asset (Liability)	302	3
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	9	8
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	9	8
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
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	298	0
Assets, Fair Value Disclosure	307	8
Total mark-to-market derivative liabilities	0	0
Deferred Compensation Liability, Current and Noncurrent	0	0
Total Liabilities	0	0
Fair Value, Net Asset (Liability)	307	8
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	9	8
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	9	8
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
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
Assets, Fair Value Disclosure	0	0
Total mark-to-market derivative liabilities	0	0
Deferred Compensation Liability, Current and Noncurrent	(5)	(5)
Total Liabilities	(5)	(5)
Fair Value, Net Asset (Liability)	(5)	(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
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
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
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
Assets, Fair Value Disclosure	0	0
Total mark-to-market derivative liabilities	0	0
Deferred Compensation Liability, Current and Noncurrent	0	0
Total Liabilities	0	0
Fair Value, Net Asset (Liability)	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
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
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
Pepco Holdings LLC [Member] | Cash and Cash Equivalents [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Cash equivalents	78	57
Pepco Holdings LLC [Member] | Other Assets [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Cash equivalents	10	14
Pepco Holdings LLC [Member] | Fair Value, Recurring [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Cash equivalents	166	124
Assets, Fair Value Disclosure	303	259
Deferred Compensation Liability, Current and Noncurrent	(17)	(19)
Total Liabilities	(17)	(19)
Fair Value, Net Asset (Liability)	286	240
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	137	135
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	52	44
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
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	11	12
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	60	65
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	166	124
Assets, Fair Value Disclosure	232	182
Deferred Compensation Liability, Current and Noncurrent	0	0
Total Liabilities	0	0
Fair Value, Net Asset (Liability)	232	182
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	66	58
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	52	44
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
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
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
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
Assets, Fair Value Disclosure	37	36
Deferred Compensation Liability, Current and Noncurrent	(17)	(19)
Total Liabilities	(17)	(19)
Fair Value, Net Asset (Liability)	20	17
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	36
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
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
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	11	12
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	26	24
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
Assets, Fair Value Disclosure	34	41
Deferred Compensation Liability, Current and Noncurrent	0	0
Total Liabilities	0	0
Fair Value, Net Asset (Liability)	34	41
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	41
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
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
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
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	41
Potomac Electric Power Company [Member] | Cash and Cash Equivalents [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Cash equivalents	46	29
Potomac Electric Power Company [Member] | Fair Value, Recurring [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Cash equivalents	112	34
Assets, Fair Value Disclosure	225	144
Deferred Compensation Liability, Current and Noncurrent	(2)	(2)
Total Liabilities	(2)	(2)
Fair Value, Net Asset (Liability)	223	142
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	113	110
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	51	43
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	2	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	60	65
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	112	34
Assets, Fair Value Disclosure	163	77
Deferred Compensation Liability, Current and Noncurrent	0	0
Total Liabilities	0	0
Fair Value, Net Asset (Liability)	163	77
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	51	43
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	51	43
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
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
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
Assets, Fair Value Disclosure	28	26
Deferred Compensation Liability, Current and Noncurrent	(2)	(2)
Total Liabilities	(2)	(2)
Fair Value, Net Asset (Liability)	26	24
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	28	26
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
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	2	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	26	24
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
Assets, Fair Value Disclosure	34	41
Deferred Compensation Liability, Current and Noncurrent	0	0
Total Liabilities	0	0
Fair Value, Net Asset (Liability)	34	41
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	41
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
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
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	41
Delmarva Power and Light Company [Member] | Cash and Cash Equivalents [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Cash equivalents	9	13
Delmarva Power and Light Company [Member] | Fair Value, Recurring [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Cash equivalents	17	0
Assets, Fair Value Disclosure	17	0
Deferred Compensation Liability, Current and Noncurrent	0	0
Total Liabilities	0	0
Fair Value, Net Asset (Liability)	17	0
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
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
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
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
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	17	0
Assets, Fair Value Disclosure	17	0
Deferred Compensation Liability, Current and Noncurrent	0	0
Total Liabilities	0	0
Fair Value, Net Asset (Liability)	17	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
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
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
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
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
Assets, Fair Value Disclosure	0	0
Deferred Compensation Liability, Current and Noncurrent	0	0
Total Liabilities	0	0
Fair Value, Net Asset (Liability)	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
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
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
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
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
Assets, Fair Value Disclosure	0	0
Deferred Compensation Liability, Current and Noncurrent	0	0
Total Liabilities	0	0
Fair Value, Net Asset (Liability)	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
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
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
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
Atlantic City Electric Company [Member] | Cash and Cash Equivalents [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Cash equivalents	13	12
Atlantic City Electric Company [Member] | Other Assets [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Cash equivalents	10	14
Atlantic City Electric Company [Member] | Fair Value, Recurring [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Cash equivalents	14	16
Assets, Fair Value Disclosure	14	16
Deferred Compensation Liability, Current and Noncurrent	0	0
Total Liabilities	0	0
Fair Value, Net Asset (Liability)	14	16
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
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
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
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
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	16
Assets, Fair Value Disclosure	14	16
Deferred Compensation Liability, Current and Noncurrent	0	0
Total Liabilities	0	0
Fair Value, Net Asset (Liability)	14	16
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
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
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
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
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
Assets, Fair Value Disclosure	0	0
Deferred Compensation Liability, Current and Noncurrent	0	0
Total Liabilities	0	0
Fair Value, Net Asset (Liability)	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
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
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
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
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
Assets, Fair Value Disclosure	0	0
Deferred Compensation Liability, Current and Noncurrent	0	0
Total Liabilities	0	0
Fair Value, Net Asset (Liability)	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
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
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
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
Maturity Less than 30 Days [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	121	90
Maturity Less than 30 Days [Member] | Exelon Generation Co L L C [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	$ 121	$ 90