Goodwill and Other Intangible Assets (Narrative) (Details) - USD ($) $ in Millions		3 Months Ended	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Feb. 18, 2015
Goodwill [Line Items]
Goodwill impairment expense			$ 0	$ 317	$ 164
Goodwill	$ 1,157	$ 1,157	1,157	1,157	1,458
Goodwill, Acquired During Period				16
Goodwill	3,912	3,912	3,912	$ 3,912	$ 3,896
Main street power [Member]
Goodwill [Line Items]
Business Acquisition, Percentage of Voting Interests Acquired						100.00%
Goodwill, Acquired During Period	$ 16
DPL Subsidiary [Member]
Goodwill [Line Items]
Goodwill impairment expense		$ 317
Goodwill			$ 317