Shareholder Equity Preferred and Preference Securities (Details) - USD ($) $ / shares in Units, $ in Millions	Dec. 31, 2016	Dec. 31, 2015
Baltimore Gas and Electric Company [Member]
Class of Stock [Line Items]
Preferred Stock, Value, Outstanding	$ 0	$ 190
Preferred Stock, Shares Outstanding	0.00	1,900,000.00
Pepco Holdings LLC [Member] | Predecessor [Member]
Class of Stock [Line Items]
Preferred Stock, Shares Outstanding		18,000
Series 6.97% Preferred Stock [Member] | Baltimore Gas and Electric Company [Member]
Class of Stock [Line Items]
Preferred Stock, Value, Outstanding	$ 0	$ 50
Preferred Stock, Redemption Price Per Share	$ 100.00
Preferred Stock, Shares Outstanding	0.00	500,000.00
Series 6.7% Preferred Stock [Member] | Baltimore Gas and Electric Company [Member]
Class of Stock [Line Items]
Preferred Stock, Value, Outstanding	$ 0	$ 40
Preferred Stock, Redemption Price Per Share	$ 100.00
Preferred Stock, Shares Outstanding	0.00	400,000.00
Series 6.99% Preferred Stock [Member] | Baltimore Gas and Electric Company [Member]
Class of Stock [Line Items]
Preferred Stock, Value, Outstanding	$ 0	$ 60
Preferred Stock, Redemption Price Per Share	$ 100.00
Preferred Stock, Shares Outstanding	0.00	600,000.00
Series 7.125% Preferred Stock [Member] | Baltimore Gas and Electric Company [Member]
Class of Stock [Line Items]
Preferred Stock, Value, Outstanding	$ 0	$ 40
Preferred Stock, Redemption Price Per Share	$ 100.00
Preferred Stock, Shares Outstanding	0.00	400,000.00