Significant Accounting Policies - Narrative (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Significant Accounting Policies Additional Narrative Information [Line Items]
Retained earnings	$ 6,426	$ 5,490
Regulatory Liabilities	10,609	9,965
Deferred income taxes and unamortized investment tax credits	12,793	11,956
Net income	$ 2,460	2,328	$ 2,171
Minimum expectation of tax position to be realized	50.00%
Prior Period Adjustment [Abstract]
Prior Period Reclassification Adjustment		310
Corporate, Non-Segment
Significant Accounting Policies Additional Narrative Information [Line Items]
Retained earnings	$ 6,426	5,490
Net income	$ 2,460	$ 2,328	2,170
Commonwealth Edison Co | Corporate, Non-Segment
Significant Accounting Policies Additional Narrative Information [Line Items]
Percentage ownership of consolidated subsidiaries	99.00%	99.00%
Exelon significant subsidiaries | Corporate, Non-Segment
Significant Accounting Policies Additional Narrative Information [Line Items]
Percentage ownership of consolidated subsidiaries	100.00%	100.00%
Pepco Holdings LLC
Significant Accounting Policies Additional Narrative Information [Line Items]
Retained earnings	$ (240)	$ (275)
Regulatory Liabilities	863	975
Deferred income taxes and unamortized investment tax credits	3,190	3,031
Net income	$ 741	590	608
Prior Period Adjustment [Abstract]
Prior Period Reclassification Adjustment		$ 163
Pepco Holdings LLC | Potomac Electric Power Company
Significant Accounting Policies Additional Narrative Information [Line Items]
Percentage ownership of consolidated subsidiaries	100.00%	100.00%
Pepco Holdings LLC | Delmarva Power & Light Company
Significant Accounting Policies Additional Narrative Information [Line Items]
Percentage ownership of consolidated subsidiaries	100.00%	100.00%
Pepco Holdings LLC | Atlantic City Electric Company
Significant Accounting Policies Additional Narrative Information [Line Items]
Percentage ownership of consolidated subsidiaries	100.00%	100.00%
Atlantic City Electric Company
Significant Accounting Policies Additional Narrative Information [Line Items]
Retained earnings	$ 10	$ (18)
Regulatory Liabilities	156	146
Deferred income taxes and unamortized investment tax credits	816	771
Net income	155	120	148
Restricted Cash and Cash Equivalents	0	0
Baltimore Gas and Electric Company
Significant Accounting Policies Additional Narrative Information [Line Items]
Retained earnings	2,403	2,244
Regulatory Liabilities	648	800
Deferred income taxes and unamortized investment tax credits	2,099	1,945
Net income	527	485	380
Prior Period Adjustment [Abstract]
Prior Period Reclassification Adjustment		147
Delmarva Power & Light Company
Significant Accounting Policies Additional Narrative Information [Line Items]
Retained earnings	627	638
Regulatory Liabilities	367	415
Deferred income taxes and unamortized investment tax credits	946	904
Net income	209	177	169
Prior Period Adjustment [Abstract]
Prior Period Reclassification Adjustment		27
Potomac Electric Power Company
Significant Accounting Policies Additional Narrative Information [Line Items]
Retained earnings	1,100	1,069
Regulatory Liabilities	327	397
Deferred income taxes and unamortized investment tax credits	1,509	1,431
Net income	$ 390	306	$ 305
Prior Period Adjustment [Abstract]
Prior Period Reclassification Adjustment		$ 136