Accounts Receivable - Purchases and Sales of Accounts Receivable (Detail) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts Receivable, Purchase	$ 1,060	$ 1,108
Commonwealth Edison Co
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts Receivable, Purchase	235	240
PECO Energy Co
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts Receivable, Purchase	297	309
Baltimore Gas and Electric Company
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts Receivable, Purchase	219	245
Pepco Holdings LLC
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts Receivable, Purchase	309	314
Potomac Electric Power Company
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts Receivable, Purchase	194	210
Delmarva Power and Light Company
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts Receivable, Purchase	60	56
Atlantic City Electric Company
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts Receivable, Purchase	$ 55	$ 48