Significant Accounting Policies - Narrative (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Significant Accounting Policies Additional Narrative Information [Line Items]
Retained earnings	$ 5,490	$ 4,597
Regulatory Liabilities	9,965	9,549
Deferred income taxes and unamortized investment tax credits	11,956	11,250
Net income	$ 2,328	2,171	$ 1,829
Minimum expectation of tax position to be realized	50.00%
Corporate, Non-Segment
Significant Accounting Policies Additional Narrative Information [Line Items]
Retained earnings	$ 5,490	4,597
Net income	$ 2,328	$ 2,170	1,706
Commonwealth Edison Co | Corporate, Non-Segment
Significant Accounting Policies Additional Narrative Information [Line Items]
Percentage ownership of consolidated subsidiaries	99.00%	99.00%
Exelon Generation Co L L C
Significant Accounting Policies Additional Narrative Information [Line Items]
Percentage ownership of consolidated subsidiaries		100.00%
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	$ (275)	$ (352)
Regulatory Liabilities	975	1,087
Deferred income taxes and unamortized investment tax credits	3,031	2,895
Net income	$ 590	$ 608	561
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	$ (18)	$ (12)
Regulatory Liabilities	146	182
Deferred income taxes and unamortized investment tax credits	771	734
Net income	120	148	$ 146
Restricted Cash and Cash Equivalents	$ 0	$ 0