Debt and Credit Agreements - Summary of Credit Facility Thresholds (Details)	12 Months Ended
	Dec. 31, 2016
Line of Credit Facility [Line Items]
Basis Points For Prime Based Borrowings	27.50%
Basis Points For Libor Based Borrowings	127.5
Credit agreement threshold	2.50
Exelon Generation Co L L C [Member]
Line of Credit Facility [Line Items]
Basis Points For Prime Based Borrowings	27.50%
Basis Points For Libor Based Borrowings	127.5
Credit agreement threshold	3.00
Commonwealth Edison Co [Member]
Line of Credit Facility [Line Items]
Basis Points For Prime Based Borrowings	7.50%
Basis Points For Libor Based Borrowings	107.5
Credit agreement threshold	2.00
PECO Energy Co [Member]
Line of Credit Facility [Line Items]
Basis Points For Prime Based Borrowings	0.00%
Basis Points For Libor Based Borrowings	90.0
Credit agreement threshold	2.00
Baltimore Gas and Electric Company [Member]
Line of Credit Facility [Line Items]
Basis Points For Prime Based Borrowings	0.00%
Basis Points For Libor Based Borrowings	100.0
Credit agreement threshold	2.00
Potomac Electric Power Company [Member]
Line of Credit Facility [Line Items]
Basis Points For Prime Based Borrowings	7.50%
Basis Points For Libor Based Borrowings	107.5
Credit agreement threshold	2.00
Delmarva Power and Light Company [Member]
Line of Credit Facility [Line Items]
Basis Points For Prime Based Borrowings	7.50%
Basis Points For Libor Based Borrowings	107.5
Credit agreement threshold	2.00
Atlantic City Electric Company [Member]
Line of Credit Facility [Line Items]
Basis Points For Prime Based Borrowings	7.50%
Basis Points For Libor Based Borrowings	107.5
Credit agreement threshold	2.00