Asset Impairment Expense (Narrative) (Details) (USD $)	12 Months Ended			0 Months Ended	12 Months Ended				3 Months Ended		12 Months Ended							1 Months Ended	12 Months Ended
	Dec. 31, 2013 MW	Dec. 31, 2012	Dec. 31, 2011	Jan. 09, 2013 Beaver Valley MW	Dec. 31, 2013 Beaver Valley		Dec. 31, 2012 Beaver Valley	Dec. 31, 2011 Beaver Valley	Dec. 31, 2013 DP&L (Conesville) MW		Dec. 31, 2012 DP&L (Conesville)	Dec. 31, 2011 DP&L (Conesville)	Dec. 31, 2013 Itabo (San Lorenzo)		Dec. 31, 2012 Itabo (San Lorenzo)	Dec. 31, 2011 Itabo (San Lorenzo)	Sep. 30, 2013 Itabo (San Lorenzo) MW	Jun. 30, 2013 Wind Turbines And Projects	Dec. 31, 2013 Wind Turbines And Projects		Dec. 31, 2012 Wind Turbines And Projects	Dec. 31, 2011 Wind Turbines And Projects	Dec. 31, 2013 Kelanitissa	Dec. 31, 2012 Kelanitissa	Dec. 31, 2011 Kelanitissa	Dec. 31, 2013 St. Patrick	Dec. 31, 2012 St. Patrick	Dec. 31, 2011 St. Patrick
Debt Instrument [Line Items]
Production Capacity (MW)	2,465			125					129								35
Lump sum payment received for termination of PPA				$ 60,000,000
Other Asset Impairment Charges	95,000,000	73,000,000	173,000,000		46,000,000	[1]	0	0	26,000,000	[1]	0	0	16,000,000	[1]	0	0			0		41,000,000	116,000,000	0	19,000,000	42,000,000	0	11,000,000	0
Assets carrying amount																	23,000,000										33,000,000
Assets, fair value									0								7,000,000		0	[1]							22,000,000
Gain (loss) on sale of assets	$ (14,000,000)	$ 174,000,000	$ (20,000,000)															$ 2,000,000

[1] See Note 21 — Asset Impairment Expense for further information.