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Significant Accounting Policies - Narrative (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020	Jan. 01, 2021
Significant Accounting Policies Additional Narrative Information [Line Items]
Retained earnings/Undistributed earnings (losses)	$ 4,597	$ 16,942
Regulatory Liabilities	9,549	10,004
Deferred income taxes and unamortized investment tax credits	11,250	10,611
Net income (loss)	$ 2,171	1,829	$ 1,954
Minimum expectation of tax position to be realized	50.00%
Corporate, Non-Segment [Member]
Significant Accounting Policies Additional Narrative Information [Line Items]
Retained earnings/Undistributed earnings (losses)	$ 4,597	16,942
Net income (loss)	$ 2,170	$ 1,706	1,963
Commonwealth Edison Company [Member] \| Corporate, Non-Segment [Member]
Significant Accounting Policies Additional Narrative Information [Line Items]
Percentage ownership of consolidated subsidiaries	99.00%	99.00%
Exelon Generation Co L L C [Member]
Significant Accounting Policies Additional Narrative Information [Line Items]
Percentage ownership of consolidated subsidiaries		100.00%
Exelon significant subsidiaries \| Corporate, Non-Segment [Member]
Significant Accounting Policies Additional Narrative Information [Line Items]
Percentage ownership of consolidated subsidiaries	100.00%	100.00%
Pepco Holdings LLC [Member]
Significant Accounting Policies Additional Narrative Information [Line Items]
Retained earnings/Undistributed earnings (losses)	$ (352)	$ (210)
Regulatory Liabilities	1,087	1,306
Deferred income taxes and unamortized investment tax credits	2,895	2,675
Net income (loss)	608	$ 561	495
Pepco Holdings LLC [Member] \| Pepco Holdings LLC [Member]
Significant Accounting Policies Additional Narrative Information [Line Items]
Net income (loss)	$ 8
Pepco Holdings LLC [Member] \| Potomac Electric Power Company [Member]
Significant Accounting Policies Additional Narrative Information [Line Items]
Percentage ownership of consolidated subsidiaries	100.00%	100.00%
Pepco Holdings LLC [Member] \| Delmarva Power & Light Company [Member]
Significant Accounting Policies Additional Narrative Information [Line Items]
Percentage ownership of consolidated subsidiaries	100.00%	100.00%
Pepco Holdings LLC [Member] \| Atlantic City Electric Company [Member]
Significant Accounting Policies Additional Narrative Information [Line Items]
Percentage ownership of consolidated subsidiaries	100.00%	100.00%
Atlantic City Electric Company [Member]
Significant Accounting Policies Additional Narrative Information [Line Items]
Retained earnings/Undistributed earnings (losses)	$ (12)	$ (15)
Regulatory Liabilities	182	242
Deferred income taxes and unamortized investment tax credits	734	682
Net income (loss)	$ 148	146	$ 112
Atlantic City Electric Company [Member] \| Atlantic City Electric Company [Member]
Significant Accounting Policies Additional Narrative Information [Line Items]
Retained earnings/Undistributed earnings (losses)				$ 8
Regulatory Liabilities				11
Deferred income taxes and unamortized investment tax credits				$ 3
Net income (loss)		$ 1