Accounts Receivable - Purchases and Sales of Accounts Receivable (Detail) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2026	Sep. 30, 2025
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts Receivable, Purchase	$ 3,708	$ 3,320
Commonwealth Edison Co
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts Receivable, Purchase	967	814
PECO Energy Co
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts Receivable, Purchase	1,091	954
Baltimore Gas and Electric Company
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts Receivable, Purchase	492	550
Pepco Holdings LLC
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts Receivable, Purchase	1,158	1,002
Potomac Electric Power Company
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts Receivable, Purchase	745	624
Delmarva Power and Light Company
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts Receivable, Purchase	209	201
Atlantic City Electric Company
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts Receivable, Purchase	$ 204	$ 177