Consolidated Statements of Results of Operations (USD $) In Millions, except Per Share data, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Operating expenses:
Goodwill Impairment	$ 1,850.0		$ 1,850.0
Other income / (expense), net:
Earnings on common stock		67.1		142.3
Average number of common shares outstanding (millions):
Basic		115.0		114.4
Diluted		115.5		115.0
Earnings per share of common stock:
Basic		$ 0.60		$ 1.20
Diluted		$ 0.60		$ 1.20
THE DAYTON POWER AND LIGHT COMPANY [Member]
Revenues	426.8	452.5	1,173.0	1,299.2
Cost of revenues:
Fuel	108.1	124.0	272.3	311.7
Purchased power	79.9	95.6	234.1	317.8
Total cost of revenues	188.0	219.6	506.4	629.5
Gross margin	238.8	232.9	666.6	669.7
Operating expenses:
Operation and maintenance	103.6	80.2	298.8	266.7
Depreciation and amortization	36.5	33.8	107.3	100.3
General taxes	14.3	18.9	54.1	57.6
Fixed asset impairment	80.8		80.8
Total operating expenses	235.2	132.9	541.0	424.6
Operating income	3.6	100.0	125.6	245.1
Other income / (expense), net:
Investment income	1.9	0.4	2.1	1.5
Interest expense	(10.0)	(9.3)	(29.0)	(28.7)
Other expense	(0.2)	(0.4)	(1.0)	(1.2)
Total other income / (expense), net	(8.3)	(9.3)	(27.9)	(28.4)
Earnings before income tax	(4.7)	90.7	97.7	216.7
Income tax expense	6.5	26.8	39.4	69.3
Net income	(11.2)	63.9	58.3	147.4
Dividends on preferred stock	0.2	0.2	0.6	0.6
Earnings on common stock	(11.4)	63.7	57.7	146.8
Successor [Member]
Revenues	471.7		1,287.7
Cost of revenues:
Fuel	112.7		279.0
Purchased power	90.7		265.8
Amortization of intangibles	24.2		71.2
Total cost of revenues	227.6		616.0
Gross margin	244.1		671.7
Operating expenses:
Operation and maintenance	106.6		312.1
Depreciation and amortization	33.1		95.6
General taxes	15.7		58.7
Goodwill Impairment	1,850.0		1,850.0
Total operating expenses	2,005.4		2,316.4
Operating income	(1,761.3)		(1,644.7)
Other income / (expense), net:
Investment income	1.9		2.2
Interest expense	(31.1)		(93.1)
Other expense	(0.2)		(1.4)
Total other income / (expense), net	(29.4)		(92.3)
Earnings before income tax	(1,790.7)		(1,737.0)
Income tax expense	20.2		40.3
Net income	(1,810.9)		(1,777.3)
Predecessor [Member]
Revenues		497.6		1,411.5
Cost of revenues:
Fuel		129.0		320.9
Purchased power		108.3		342.7
Total cost of revenues		237.3		663.6
Gross margin		260.3		747.9
Operating expenses:
Operation and maintenance		92.0		298.2
Depreciation and amortization		35.8		106.0
General taxes		19.6		64.2
Total operating expenses		147.4		468.4
Operating income		112.9		279.5
Other income / (expense), net:
Investment income		0.1		0.3
Interest expense		(16.8)		(51.3)
Charge for early redemption of debt				(15.3)
Other expense		(0.5)		(1.2)
Total other income / (expense), net		(17.2)		(67.5)
Earnings before income tax		95.7		212.0
Income tax expense		28.6		69.7
Net income		$ 67.1		$ 142.3
Average number of common shares outstanding (millions):
Basic		115.0		114.4
Diluted		115.5		115.0
Earnings per share of common stock:
Basic		$ 0.58		$ 1.24
Diluted		$ 0.58		$ 1.24
Dividends paid per share of common stock		$ 0.3325		$ 0.9975