Accounts Receivable - Allowance for Credit Losses Rollforward (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021
Accounts, Notes, Loans and Financing Receivable [Line Items]
Current period provision for expected credit losses			$ (96)	$ (100)
Commonwealth Edison Co [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Current period provision for expected credit losses			(29)	(24)
PECO Energy Co [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Current period provision for expected credit losses			(21)	(17)
Baltimore Gas and Electric Company [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Current period provision for expected credit losses			(18)	(4)
Pepco Holdings LLC [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Current period provision for expected credit losses			(29)	(9)
Potomac Electric Power Company [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Current period provision for expected credit losses			(16)	(5)
Delmarva Power and Light Company [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Current period provision for expected credit losses			(6)	(2)
Atlantic City Electric Company [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Current period provision for expected credit losses			(7)	(2)
Customer accounts receivable
Accounts, Notes, Loans and Financing Receivable [Line Items]
Beginning balance	$ 389	$ 377	320	334
Current period provision for expected credit losses	(9)	(42)	101	28
Writeoffs, net of recoveries	26	15	67	42
Ending balance	354	320	354	320
Customer accounts receivable | Commonwealth Edison Co [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Beginning balance	92	103	73	97
Current period provision for expected credit losses	(5)	(9)	21	12
Writeoffs, net of recoveries	6	5	13	20
Ending balance	81	89	81	89
Customer accounts receivable | PECO Energy Co [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Beginning balance	125	130	105	116
Current period provision for expected credit losses	(10)	(14)	21	6
Writeoffs, net of recoveries	8	5	19	11
Ending balance	107	111	107	111
Customer accounts receivable | Baltimore Gas and Electric Company [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Beginning balance	59	43	38	35
Current period provision for expected credit losses	2	(14)	28	(5)
Writeoffs, net of recoveries	4	2	9	3
Ending balance	57	27	57	27
Customer accounts receivable | Pepco Holdings LLC [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Beginning balance	113	101	104	86
Current period provision for expected credit losses	4	(5)	31	15
Writeoffs, net of recoveries	8	3	26	8
Ending balance	109	93	109	93
Customer accounts receivable | Potomac Electric Power Company [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Beginning balance	40	41	37	32
Current period provision for expected credit losses	5	(1)	16	10
Writeoffs, net of recoveries	3	2	11	4
Ending balance	42	38	42	38
Customer accounts receivable | Delmarva Power and Light Company [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Beginning balance	24	25	18	22
Current period provision for expected credit losses	0	(5)	7	1
Writeoffs, net of recoveries	2	1	3	4
Ending balance	22	19	22	19
Customer accounts receivable | Atlantic City Electric Company [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Beginning balance	49	35	49	32
Current period provision for expected credit losses	(1)	1	8	4
Writeoffs, net of recoveries	3	0	12	0
Ending balance	45	36	45	36
Other receivables
Accounts, Notes, Loans and Financing Receivable [Line Items]
Beginning balance	81	79	72	71
Current period provision for expected credit losses	2	(5)	15	5
Writeoffs, net of recoveries	2	3	6	5
Ending balance	81	71	81	71
Other receivables | Commonwealth Edison Co [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Beginning balance	20	22	17	21
Current period provision for expected credit losses	(2)	(3)	2	(2)
Writeoffs, net of recoveries	0	1	1	1
Ending balance	18	18	18	18
Other receivables | PECO Energy Co [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Beginning balance	9	11	7	8
Current period provision for expected credit losses	2	(3)	4	1
Writeoffs, net of recoveries	1	1	1	2
Ending balance	10	7	10	7
Other receivables | Baltimore Gas and Electric Company [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Beginning balance	11	9	9	9
Current period provision for expected credit losses	1	0	4	1
Writeoffs, net of recoveries	1	1	2	2
Ending balance	11	8	11	8
Other receivables | Pepco Holdings LLC [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Beginning balance	41	37	39	33
Current period provision for expected credit losses	1	1	5	5
Writeoffs, net of recoveries	0	0	2	0
Ending balance	42	38	42	38
Other receivables | Potomac Electric Power Company [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Beginning balance	18	15	16	13
Current period provision for expected credit losses	2	1	4	3
Writeoffs, net of recoveries	0	0	0	0
Ending balance	20	16	20	16
Other receivables | Delmarva Power and Light Company [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Beginning balance	9	10	8	9
Current period provision for expected credit losses	(1)	(1)	0	0
Writeoffs, net of recoveries	0	0	0	0
Ending balance	8	9	8	9
Other receivables | Atlantic City Electric Company [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Beginning balance	14	12	15	11
Current period provision for expected credit losses	0	1	1	2
Writeoffs, net of recoveries	0	0	2	0
Ending balance	$ 14	$ 13	$ 14	$ 13