Debt Obligations (Current portion - Long-term Debt) (Details) (USD $) In Millions, unless otherwise specified					3 Months Ended	12 Months Ended	3 Months Ended	6 Months Ended	12 Months Ended	3 Months Ended	12 Months Ended			3 Months Ended			3 Months Ended		3 Months Ended	12 Months Ended
	Mar. 31, 2014	Dec. 31, 2013	Mar. 31, 2014 DP&L [Member]	Dec. 31, 2013 DP&L [Member]	Mar. 31, 2014 Pollution control series maturing in November 2040 - variable rates: 0.04% - 0.26% and 0.06% - 0.32% [Member]	Dec. 31, 2013 Pollution control series maturing in November 2040 - variable rates: 0.04% - 0.26% and 0.06% - 0.32% [Member]	Mar. 31, 2014 Pollution control series maturing in November 2040 - variable rates: 0.04% - 0.26% and 0.06% - 0.32% [Member] DP&L [Member]	Jun. 30, 2013 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 Pollution control series maturing in November 2040 - variable rates: 0.04% - 0.26% and 0.06% - 0.32% [Member] DP&L [Member]	Mar. 31, 2014 First Mortgage Bonds Maturing in October 2013 - 5.125% [Member]	Dec. 31, 2013 First Mortgage Bonds Maturing in October 2013 - 5.125% [Member]	Mar. 31, 2014 First Mortgage Bonds Maturing in October 2013 - 5.125% [Member] DP&L [Member]	Dec. 31, 2013 First Mortgage Bonds Maturing in October 2013 - 5.125% [Member] DP&L [Member]	Mar. 31, 2014 U.S. Government note maturing in February 2061 - 4.20% [Member]	Dec. 31, 2013 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]	Mar. 31, 2014 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]	Mar. 31, 2014 Bank Term Loan maturing in May 2018 [Member]	Dec. 31, 2013 Bank Term Loan maturing in May 2018 [Member]
Obligation for capital lease	$ 0.1	$ 0.1	$ 0.1	$ 0.1
Current portion - long-term debt	20.2	10.2	0.2	0.2						20.0	10.0	0.1	0.1
Debt instrument maturity year					Nov. 01, 2040		Nov. 01, 2040			May 01, 2018				Feb. 01, 2061			Feb. 01, 2061		May 01, 2018
Debt instrument interest percentage														4.20%		4.20%	4.20%	4.20%
Debt instrument interest percentage minimum					0.04%	0.05%	0.04%		0.05%	2.41%	2.42%			4.20%			4.20%		2.41%	2.42%
Debt instrument interest percentage maximum					0.08%	0.24%		0.08%	0.24%	2.42%	2.45%								2.42%	2.45%
U.S. Government note maturing in February 2061 - 4.20%, current														$ 0.1	$ 0.1