Accounts Receivable - Purchases and Sales of Accounts Receivable (Detail) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts Receivable, Purchase	$ 3,177	$ 3,124
Commonwealth Edison Co
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts Receivable, Purchase	750	726
PECO Energy Co
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts Receivable, Purchase	854	843
Baltimore Gas and Electric Company
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts Receivable, Purchase	606	628
Pepco Holdings LLC
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts Receivable, Purchase	967	927
Potomac Electric Power Company
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts Receivable, Purchase	607	600
Delmarva Power and Light Company
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts Receivable, Purchase	191	174
Atlantic City Electric Company
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts Receivable, Purchase	$ 169	$ 153