Debt Obligations (Long-term Debt) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended	12 Months Ended			3 Months Ended	12 Months Ended	3 Months Ended			3 Months Ended			3 Months Ended		3 Months Ended		3 Months Ended		3 Months Ended		3 Months Ended		3 Months Ended		3 Months Ended	12 Months Ended	3 Months Ended		6 Months Ended	12 Months Ended			3 Months Ended		3 Months Ended			3 Months Ended	12 Months Ended	3 Months Ended		3 Months Ended			3 Months Ended
	Mar. 31, 2014	Dec. 31, 2013	Mar. 31, 2014 DP&L [Member]	Dec. 31, 2013 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 September 2016	Dec. 31, 2013 First Mortgage Bonds Maturing in September 2016	Sep. 13, 2013 First Mortgage Bonds Maturing in September 2016	Mar. 31, 2014 First Mortgage Bonds Maturing in September 2016 DP&L [Member]	Dec. 31, 2013 First Mortgage Bonds Maturing in September 2016 DP&L [Member]	Sep. 30, 2013 First Mortgage Bonds Maturing in September 2016 DP&L [Member]	Mar. 31, 2014 Pollution Control Series Maturing in January 2028 - 4.70% [Member]	Dec. 31, 2013 Pollution Control Series Maturing in January 2028 - 4.70% [Member]	Mar. 31, 2014 Pollution Control Series Maturing in January 2028 - 4.70% [Member] DP&L [Member]	Dec. 31, 2013 Pollution Control Series Maturing in January 2028 - 4.70% [Member] DP&L [Member]	Mar. 31, 2014 Pollution Control Series Maturing in January 2034 - 4.80% [Member]	Dec. 31, 2013 Pollution Control Series Maturing in January 2034 - 4.80% [Member]	Mar. 31, 2014 Pollution Control Series Maturing in January 2034 - 4.80% [Member] DP&L [Member]	Dec. 31, 2013 Pollution Control Series Maturing in January 2034 - 4.80% [Member] DP&L [Member]	Mar. 31, 2014 Pollution Control Series Maturing in September 2036 - 4.80% [Member]	Dec. 31, 2013 Pollution Control Series Maturing in September 2036 - 4.80% [Member]	Mar. 31, 2014 Pollution Control Series Maturing in September 2036 - 4.80% [Member] DP&L [Member]	Dec. 31, 2013 Pollution Control Series Maturing in September 2036 - 4.80% [Member] 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]	Dec. 31, 2013 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 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]	Dec. 31, 2013 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]	Mar. 31, 2014 Note to DPL Capital Trust II Maturing in September 2031 - 8.125% [Member]	Dec. 31, 2013 Note to DPL Capital Trust II Maturing in September 2031 - 8.125% [Member]	Mar. 31, 2014 Five Year Senior Unsecured Notes at 6.50% maturing on October 15, 2016 [Member]	Dec. 31, 2013 Five Year Senior Unsecured Notes at 6.50% maturing on October 15, 2016 [Member]	Oct. 03, 2011 Five Year Senior Unsecured Notes at 6.50% maturing on October 15, 2016 [Member]	Mar. 31, 2014 Ten Year Senior Unsecured Notes at 7.25% maturing at October 15, 2021 [Member]	Dec. 31, 2013 Ten Year Senior Unsecured Notes at 7.25% maturing at October 15, 2021 [Member]	Oct. 03, 2011 Ten Year Senior Unsecured Notes at 7.25% maturing at October 15, 2021 [Member]
Long-term debt, gross							$ 444.4	$ 444.3	$ 445.0	$ 445.0	$ 445.0	$ 445.0	$ 36.0	$ 36.0	$ 35.3	$ 35.3	$ 179.6	$ 179.6	$ 179.1	$ 179.1	$ 96.4	$ 96.4	$ 100.0	$ 100.0	$ 100.0	$ 100.0	$ 100.0	[1]			$ 100.0	[1]		$ 18.7	$ 18.2	$ 18.2	$ 18.7	$ 170.0	$ 180.0	$ 19.6	$ 19.6	$ 430.0	$ 430.0		$ 780.0	$ 780.0
Total long-term debt at subsidary	874.6	874.6
Unamortized debt discount	18.2	18.3	(0.7)	(0.7)
Total long-term debt	$ 2,274.2	$ 2,284.2	$ 876.9	$ 876.9
Debt instrument maturity year					May 01, 2018		Sep. 01, 2016			Sep. 01, 2016			Jan. 01, 2028		Jan. 01, 2028		Jan. 01, 2034		Jan. 01, 2034		Sep. 01, 2036		Sep. 01, 2036		Nov. 01, 2040		Nov. 01, 2040						Feb. 01, 2061		Feb. 01, 2061			May 01, 2018		Sep. 01, 2031		Oct. 01, 2016			Oct. 01, 2021
Debt instrument interest percentage							1.88%			1.875%			4.70%		4.70%		4.80%		4.80%		4.80%		4.80%										4.20%	4.20%	4.20%		4.20%			8.125%		6.50%		6.50%	7.25%		7.25%
Debt instrument interest percentage minimum					2.41%	2.42%																			0.04%	0.05%	0.04%			0.05%			4.20%		4.20%			2.41%	2.42%
Debt instrument interest percentage maximum					2.42%	2.45%																			0.08%	0.24%			0.08%	0.24%								2.42%	2.45%

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