Fair Value of Financial Assets and Liabilities - Fair Value of Financial Liabilities Recorded at Amortized Cost (Details) - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022
Estimate of Fair Value Measurement [Member] | Related Party
Financial Instruments, Financial Liabilities, Balance Sheet Groupings [Abstract]
Long-term debt (including amounts due within one year)	$ 390	$ 384
Estimate of Fair Value Measurement [Member] | Nonrelated Party
Financial Instruments, Financial Liabilities, Balance Sheet Groupings [Abstract]
Long-term debt (including amounts due within one year)	37,246	32,229
Estimate of Fair Value Measurement [Member] | Fair Value, Inputs, Level 1 [Member] | Related Party
Financial Instruments, Financial Liabilities, Balance Sheet Groupings [Abstract]
Long-term debt (including amounts due within one year)	0	0
Estimate of Fair Value Measurement [Member] | Fair Value, Inputs, Level 1 [Member] | Nonrelated Party
Financial Instruments, Financial Liabilities, Balance Sheet Groupings [Abstract]
Long-term debt (including amounts due within one year)	0	0
Estimate of Fair Value Measurement [Member] | Fair Value, Inputs, Level 2 [Member] | Related Party
Financial Instruments, Financial Liabilities, Balance Sheet Groupings [Abstract]
Long-term debt (including amounts due within one year)	0	0
Estimate of Fair Value Measurement [Member] | Fair Value, Inputs, Level 2 [Member] | Nonrelated Party
Financial Instruments, Financial Liabilities, Balance Sheet Groupings [Abstract]
Long-term debt (including amounts due within one year)	33,804	29,902
Estimate of Fair Value Measurement [Member] | Fair Value, Inputs, Level 3 [Member] | Related Party
Financial Instruments, Financial Liabilities, Balance Sheet Groupings [Abstract]
Long-term debt (including amounts due within one year)	390	384
Estimate of Fair Value Measurement [Member] | Fair Value, Inputs, Level 3 [Member] | Nonrelated Party
Financial Instruments, Financial Liabilities, Balance Sheet Groupings [Abstract]
Long-term debt (including amounts due within one year)	3,442	2,327
Reported Value Measurement [Member] | Related Party
Financial Instruments, Financial Liabilities, Balance Sheet Groupings [Abstract]
Long-term debt (including amounts due within one year)	390	390
Reported Value Measurement [Member] | Nonrelated Party
Financial Instruments, Financial Liabilities, Balance Sheet Groupings [Abstract]
Long-term debt (including amounts due within one year)	41,095	37,074
Long-term debt (including amounts due within one year)	582	626
Commonwealth Edison Co | Estimate of Fair Value Measurement [Member] | Related Party
Financial Instruments, Financial Liabilities, Balance Sheet Groupings [Abstract]
Long-term debt (including amounts due within one year)	208	204
Commonwealth Edison Co | Estimate of Fair Value Measurement [Member] | Nonrelated Party
Financial Instruments, Financial Liabilities, Balance Sheet Groupings [Abstract]
Long-term debt (including amounts due within one year)	10,210	9,006
Commonwealth Edison Co | Estimate of Fair Value Measurement [Member] | Fair Value, Inputs, Level 1 [Member] | Related Party
Financial Instruments, Financial Liabilities, Balance Sheet Groupings [Abstract]
Long-term debt (including amounts due within one year)	0	0
Commonwealth Edison Co | Estimate of Fair Value Measurement [Member] | Fair Value, Inputs, Level 1 [Member] | Nonrelated Party
Financial Instruments, Financial Liabilities, Balance Sheet Groupings [Abstract]
Long-term debt (including amounts due within one year)	0	0
Commonwealth Edison Co | Estimate of Fair Value Measurement [Member] | Fair Value, Inputs, Level 2 [Member] | Related Party
Financial Instruments, Financial Liabilities, Balance Sheet Groupings [Abstract]
Long-term debt (including amounts due within one year)	0	0
Commonwealth Edison Co | Estimate of Fair Value Measurement [Member] | Fair Value, Inputs, Level 2 [Member] | Nonrelated Party
Financial Instruments, Financial Liabilities, Balance Sheet Groupings [Abstract]
Long-term debt (including amounts due within one year)	10,210	9,006
Commonwealth Edison Co | Estimate of Fair Value Measurement [Member] | Fair Value, Inputs, Level 3 [Member] | Related Party
Financial Instruments, Financial Liabilities, Balance Sheet Groupings [Abstract]
Long-term debt (including amounts due within one year)	208	204
Commonwealth Edison Co | Estimate of Fair Value Measurement [Member] | Fair Value, Inputs, Level 3 [Member] | Nonrelated Party
Financial Instruments, Financial Liabilities, Balance Sheet Groupings [Abstract]
Long-term debt (including amounts due within one year)	0	0
Commonwealth Edison Co | Reported Value Measurement [Member] | Related Party
Financial Instruments, Financial Liabilities, Balance Sheet Groupings [Abstract]
Long-term debt (including amounts due within one year)	205	205
Commonwealth Edison Co | Reported Value Measurement [Member] | Nonrelated Party
Financial Instruments, Financial Liabilities, Balance Sheet Groupings [Abstract]
Long-term debt (including amounts due within one year)	11,486	10,518
PECO Energy Co | Estimate of Fair Value Measurement [Member] | Related Party
Financial Instruments, Financial Liabilities, Balance Sheet Groupings [Abstract]
Long-term debt (including amounts due within one year)	182	180
PECO Energy Co | Estimate of Fair Value Measurement [Member] | Nonrelated Party
Financial Instruments, Financial Liabilities, Balance Sheet Groupings [Abstract]
Long-term debt (including amounts due within one year)	4,562	3,914
PECO Energy Co | Estimate of Fair Value Measurement [Member] | Fair Value, Inputs, Level 1 [Member] | Related Party
Financial Instruments, Financial Liabilities, Balance Sheet Groupings [Abstract]
Long-term debt (including amounts due within one year)	0	0
PECO Energy Co | Estimate of Fair Value Measurement [Member] | Fair Value, Inputs, Level 1 [Member] | Nonrelated Party
Financial Instruments, Financial Liabilities, Balance Sheet Groupings [Abstract]
Long-term debt (including amounts due within one year)	0	0
PECO Energy Co | Estimate of Fair Value Measurement [Member] | Fair Value, Inputs, Level 2 [Member] | Related Party
Financial Instruments, Financial Liabilities, Balance Sheet Groupings [Abstract]
Long-term debt (including amounts due within one year)	0	0
PECO Energy Co | Estimate of Fair Value Measurement [Member] | Fair Value, Inputs, Level 2 [Member] | Nonrelated Party
Financial Instruments, Financial Liabilities, Balance Sheet Groupings [Abstract]
Long-term debt (including amounts due within one year)	4,562	3,864
PECO Energy Co | Estimate of Fair Value Measurement [Member] | Fair Value, Inputs, Level 3 [Member] | Related Party
Financial Instruments, Financial Liabilities, Balance Sheet Groupings [Abstract]
Long-term debt (including amounts due within one year)	182	180
PECO Energy Co | Estimate of Fair Value Measurement [Member] | Fair Value, Inputs, Level 3 [Member] | Nonrelated Party
Financial Instruments, Financial Liabilities, Balance Sheet Groupings [Abstract]
Long-term debt (including amounts due within one year)	0	50
PECO Energy Co | Reported Value Measurement [Member] | Related Party
Financial Instruments, Financial Liabilities, Balance Sheet Groupings [Abstract]
Long-term debt (including amounts due within one year)	184	184
PECO Energy Co | Reported Value Measurement [Member] | Nonrelated Party
Financial Instruments, Financial Liabilities, Balance Sheet Groupings [Abstract]
Long-term debt (including amounts due within one year)	5,134	4,612
Baltimore Gas and Electric Company | Estimate of Fair Value Measurement [Member] | Nonrelated Party
Financial Instruments, Financial Liabilities, Balance Sheet Groupings [Abstract]
Long-term debt (including amounts due within one year)	4,145	3,613
Baltimore Gas and Electric Company | Estimate of Fair Value Measurement [Member] | Fair Value, Inputs, Level 1 [Member] | Nonrelated Party
Financial Instruments, Financial Liabilities, Balance Sheet Groupings [Abstract]
Long-term debt (including amounts due within one year)	0	0
Baltimore Gas and Electric Company | Estimate of Fair Value Measurement [Member] | Fair Value, Inputs, Level 2 [Member] | Nonrelated Party
Financial Instruments, Financial Liabilities, Balance Sheet Groupings [Abstract]
Long-term debt (including amounts due within one year)	4,145	3,613
Baltimore Gas and Electric Company | Estimate of Fair Value Measurement [Member] | Fair Value, Inputs, Level 3 [Member] | Nonrelated Party
Financial Instruments, Financial Liabilities, Balance Sheet Groupings [Abstract]
Long-term debt (including amounts due within one year)	0	0
Baltimore Gas and Electric Company | Reported Value Measurement [Member] | Nonrelated Party
Financial Instruments, Financial Liabilities, Balance Sheet Groupings [Abstract]
Long-term debt (including amounts due within one year)	4,602	4,207
Pepco Holdings LLC | Estimate of Fair Value Measurement [Member] | Nonrelated Party
Financial Instruments, Financial Liabilities, Balance Sheet Groupings [Abstract]
Long-term debt (including amounts due within one year)	7,602	6,784
Pepco Holdings LLC | Estimate of Fair Value Measurement [Member] | Fair Value, Inputs, Level 1 [Member] | Nonrelated Party
Financial Instruments, Financial Liabilities, Balance Sheet Groupings [Abstract]
Long-term debt (including amounts due within one year)	0	0
Pepco Holdings LLC | Estimate of Fair Value Measurement [Member] | Fair Value, Inputs, Level 2 [Member] | Nonrelated Party
Financial Instruments, Financial Liabilities, Balance Sheet Groupings [Abstract]
Long-term debt (including amounts due within one year)	4,160	4,507
Pepco Holdings LLC | Estimate of Fair Value Measurement [Member] | Fair Value, Inputs, Level 3 [Member] | Nonrelated Party
Financial Instruments, Financial Liabilities, Balance Sheet Groupings [Abstract]
Long-term debt (including amounts due within one year)	3,442	2,277
Pepco Holdings LLC | Reported Value Measurement [Member] | Nonrelated Party
Financial Instruments, Financial Liabilities, Balance Sheet Groupings [Abstract]
Long-term debt (including amounts due within one year)	8,648	8,120
Pepco Holdings LLC
Financial Instruments, Financial Liabilities, Balance Sheet Groupings [Abstract]
Long-term debt (including amounts due within one year)	429	462
Potomac Electric Power Company | Estimate of Fair Value Measurement [Member] | Nonrelated Party
Financial Instruments, Financial Liabilities, Balance Sheet Groupings [Abstract]
Long-term debt (including amounts due within one year)	3,911	3,434
Potomac Electric Power Company | Estimate of Fair Value Measurement [Member] | Fair Value, Inputs, Level 1 [Member] | Nonrelated Party
Financial Instruments, Financial Liabilities, Balance Sheet Groupings [Abstract]
Long-term debt (including amounts due within one year)	0	0
Potomac Electric Power Company | Estimate of Fair Value Measurement [Member] | Fair Value, Inputs, Level 2 [Member] | Nonrelated Party
Financial Instruments, Financial Liabilities, Balance Sheet Groupings [Abstract]
Long-term debt (including amounts due within one year)	2,311	2,229
Potomac Electric Power Company | Estimate of Fair Value Measurement [Member] | Fair Value, Inputs, Level 3 [Member] | Nonrelated Party
Financial Instruments, Financial Liabilities, Balance Sheet Groupings [Abstract]
Long-term debt (including amounts due within one year)	1,600	1,205
Potomac Electric Power Company | Reported Value Measurement [Member] | Nonrelated Party
Financial Instruments, Financial Liabilities, Balance Sheet Groupings [Abstract]
Long-term debt (including amounts due within one year)	4,096	3,751
Delmarva Power & Light Company | Estimate of Fair Value Measurement [Member] | Nonrelated Party
Financial Instruments, Financial Liabilities, Balance Sheet Groupings [Abstract]
Long-term debt (including amounts due within one year)	1,828	1,622
Delmarva Power & Light Company | Estimate of Fair Value Measurement [Member] | Fair Value, Inputs, Level 1 [Member] | Nonrelated Party
Financial Instruments, Financial Liabilities, Balance Sheet Groupings [Abstract]
Long-term debt (including amounts due within one year)	0	0
Delmarva Power & Light Company | Estimate of Fair Value Measurement [Member] | Fair Value, Inputs, Level 2 [Member] | Nonrelated Party
Financial Instruments, Financial Liabilities, Balance Sheet Groupings [Abstract]
Long-term debt (including amounts due within one year)	694	1,164
Delmarva Power & Light Company | Estimate of Fair Value Measurement [Member] | Fair Value, Inputs, Level 3 [Member] | Nonrelated Party
Financial Instruments, Financial Liabilities, Balance Sheet Groupings [Abstract]
Long-term debt (including amounts due within one year)	1,134	458
Delmarva Power & Light Company | Reported Value Measurement [Member] | Nonrelated Party
Financial Instruments, Financial Liabilities, Balance Sheet Groupings [Abstract]
Long-term debt (including amounts due within one year)	2,080	1,938
Atlantic City Electric Company | Estimate of Fair Value Measurement [Member] | Nonrelated Party
Financial Instruments, Financial Liabilities, Balance Sheet Groupings [Abstract]
Long-term debt (including amounts due within one year)	1,647	1,523
Atlantic City Electric Company | Estimate of Fair Value Measurement [Member] | Fair Value, Inputs, Level 1 [Member] | Nonrelated Party
Financial Instruments, Financial Liabilities, Balance Sheet Groupings [Abstract]
Long-term debt (including amounts due within one year)	0	0
Atlantic City Electric Company | Estimate of Fair Value Measurement [Member] | Fair Value, Inputs, Level 2 [Member] | Nonrelated Party
Financial Instruments, Financial Liabilities, Balance Sheet Groupings [Abstract]
Long-term debt (including amounts due within one year)	939	909
Atlantic City Electric Company | Estimate of Fair Value Measurement [Member] | Fair Value, Inputs, Level 3 [Member] | Nonrelated Party
Financial Instruments, Financial Liabilities, Balance Sheet Groupings [Abstract]
Long-term debt (including amounts due within one year)	708	614
Atlantic City Electric Company | Reported Value Measurement [Member] | Nonrelated Party
Financial Instruments, Financial Liabilities, Balance Sheet Groupings [Abstract]
Long-term debt (including amounts due within one year)	$ 1,833	$ 1,757