Debt Obligations (Current portion - Long-term Debt) (Details) (USD $) In Millions, unless otherwise specified						12 Months Ended			12 Months Ended					12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Nov. 27, 2011	Dec. 31, 2012 DP&L [Member]	Dec. 31, 2011 DP&L [Member]	Dec. 31, 2012 Pollution control series maturing in November 2040 - variable rates: 0.04% - 0.26% and 0.06% - 0.32% [Member]	Dec. 31, 2012 Pollution control series maturing in November 2040 - variable rates: 0.04% - 0.26% and 0.06% - 0.32% [Member] DP&L [Member]	Dec. 31, 2012 Five Point One Two Five Percent First Mortgage Bonds Maturing In October 2013 [Member] DP&L [Member]	Dec. 31, 2012 First Mortgage Bonds Maturing in October 2013 - 5.125% [Member]	Dec. 31, 2012 First Mortgage Bonds Maturing in October 2013 - 5.125% [Member] DP&L [Member]	Dec. 31, 2012 U.S. Government note maturing in February 2061 - 4.20% [Member]	Dec. 31, 2011 U.S. Government note maturing in February 2061 - 4.20% [Member]	Mar. 01, 2011 U.S. Government note maturing in February 2061 - 4.20% [Member]	Dec. 31, 2012 U.S. Government note maturing in February 2061 - 4.20% [Member] DP&L [Member]	Dec. 31, 2011 U.S. Government note maturing in February 2061 - 4.20% [Member] DP&L [Member]	Mar. 01, 2011 U.S. Government note maturing in February 2061 - 4.20% [Member] DP&L [Member]	Sep. 01, 2011 Senior Notes Maturing in September 2011 - 6.875% [Member]
Obligation for capital lease	$ 0.3	$ 0.3		$ 0.3	$ 0.3
Current portion - long-term debt	584.9	0.4		570.4	0.4	100.0	100.0	470.0	484.5
Senior notes maturing in September 2011			297.4
Debt instrument maturity year						Nov. 01, 2040	Nov. 01, 2040		Oct. 01, 2013	Oct. 01, 2013	Feb. 01, 2061			Feb. 01, 2061
Debt instrument interest percentage			6.875%						5.125%	5.125%	4.20%		4.20%	4.20%		4.20%	6.875%
U.S. Government note maturing in February 2061 - 4.20%, current											$ 0.1	$ 0.1		$ 0.1	$ 0.1