Goodwill and Other Intangible Assets (Narrative) (Details) (USD $)	12 Months Ended			3 Months Ended	12 Months Ended		3 Months Ended
	Dec. 31, 2013 MW	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2013 DP&L	Dec. 31, 2013 DP&L	Dec. 31, 2012 DP&L	Dec. 31, 2013 MountainView MW project	Dec. 31, 2013 Buffalo Gap project MW	Sep. 30, 2013 Ebute MW	Sep. 30, 2011 Chigen
Goodwill [Line Items]
Goodwill impairment expense	$ 372,000,000	$ 1,817,000,000	$ 17,000,000	$ 307,000,000		$ 1,820,000,000	$ 7,000,000	$ 0	$ 58,000,000	$ 17,000,000
Goodwill, fair value				316,000,000	316,000,000
Effective tax rate	33.00%	298.00%	29.00%		33.00%	298.00%
Number of wind projects							2	3
Production Capacity (MW)	2,465						67	524	294
Goodwill	1,622,000,000	1,999,000,000	3,820,000,000
Amortization of intangible assets	$ 29,000,000	$ 115,000,000	$ 20,000,000