Contractual Obligations, Commercial Commitments And Contingencies (Narrative) (Details) (USD $)	3 Months Ended	9 Months Ended	12 Months Ended		0 Months Ended	2 Months Ended	3 Months Ended	4 Months Ended	12 Months Ended			3 Months Ended				2 Months Ended
	Mar. 31, 2012 T	Sep. 22, 2009 T	Dec. 31, 2011	Mar. 01, 2011	May 03, 2010 DP&L [Member]	Feb. 28, 2007 DP&L [Member] T	Mar. 31, 2012 DP&L [Member] T	May 03, 2010 DP&L [Member]	Dec. 31, 2011 DP&L [Member]	Mar. 31, 2012 DPLE and DPLER [Member]	Mar. 31, 2012 MC Squared [Member]	Mar. 31, 2012 Beckjord Unit 6 [Member]	Mar. 31, 2012 Beckjord Unit 6 [Member] DP&L [Member]	Mar. 31, 2012 Hutchings Plant [Member]	Mar. 31, 2012 Hutchings Plant [Member] DP&L [Member]	Feb. 28, 2007 Coal Supply Agreements [Member] DP&L [Member] T	Mar. 31, 2012 Debt Obligation on 4.9% Equity Ownership [Member]	Mar. 31, 2012 Debt Obligation on 4.9% Equity Ownership [Member] DP&L [Member]	Mar. 31, 2012 First Mortgage Bonds Maturing in October 2013 - 5.125% [Member]	Mar. 31, 2012 First Mortgage Bonds Maturing in October 2013 - 5.125% [Member] DP&L [Member]	Mar. 31, 2012 Pollution Control Series Maturing in January 2028 - 4.70% [Member]	Mar. 31, 2012 Pollution Control Series Maturing in January 2028 - 4.70% [Member] DP&L [Member]	Mar. 31, 2012 Pollution Control Series Maturing in January 2034 - 4.80% [Member]	Mar. 31, 2012 Pollution Control Series Maturing in January 2034 - 4.80% [Member] DP&L [Member]	Mar. 31, 2012 Pollution Control Series Maturing in September 2036 - 4.80% [Member]	Mar. 31, 2012 Pollution Control Series Maturing in September 2036 - 4.80% [Member] DP&L [Member]	Mar. 31, 2012 U.S. Government note maturing in February 2061 - 4.20% [Member]	Sep. 30, 2011 U.S. Government note maturing in February 2061 - 4.20% [Member]	Mar. 31, 2012 U.S. Government note maturing in February 2061 - 4.20% [Member] DP&L [Member]	Mar. 31, 2012 Note to DPL Capital Trust II Maturing in September 2031 - 8.125% [Member]	Dec. 31, 2011 Senior Notes Maturing in September 2011 - 6.875% [Member]	Mar. 31, 2012 Five Year Senior Unsecured Notes at 6.50% maturing on October 15, 2016 [Member]	Mar. 31, 2012 Ten Year Senior Unsecured Notes at 7.25% maturing at October 15, 2021 [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Third party guarantees	$ 47,400,000									$ 47,100,000	$ 300,000
Due to third parties, current	400,000
Equity ownership interest	4.90%						4.90%										4.90%	4.90%
Equity ownership interest aggregate cost																		64,900,000
Debt obligation																	1,324,700,000	1,324,700,000
Debt instrument interest percentage				4.20%			4.20%												5.125%	5.125%	4.70%	4.70%	4.80%	4.80%	4.80%	4.80%	4.20%	4.20%	4.20%	8.125%	6.875%	6.50%	7.25%
Environmental reserves	3,200,000						3,200,000
Percentage of coal-fire power plant holdings													50.00%		100.00%
Percentage of energy generated by coal	99.00%						99.00%
Annual CO2 emissions generation at stations, in tons	16,000,000						16,000,000
Number of tons of CO2 emitted per year including electric generating units		25,000					25,000
Number of Auxiliary Boilers	7						7
Number of diesel electric generating engines							18	18
Number of emergency black start engines					8		8
Relief and civil penalties, per day							27,500
Coal supply failure by suppliers						1,500,000										1,500,000
Coal supply agreement, in tons						570,000										570,000
Deferred liability claims							18,100,000		17,800,000
Plant Value after Merger												0		0
Interest and Other Income	$ 5,500,000		$ 5,200,000				$ 5,500,000		$ 5,200,000