Consolidated Statements of Results of Operations (USD $) In Millions, except Per Share data, unless otherwise specified	3 Months Ended
	Mar. 31, 2012	Mar. 31, 2011
Other income / (expense), net:
Earnings on common stock		$ 43.5
Average number of common shares outstanding (millions):
Basic		114.0
Diluted		114.5
Earnings per share of common stock:
Basic		$ 0.38
Diluted		$ 0.38
THE DAYTON POWER AND LIGHT COMPANY [Member]
Revenues	399.6	449.8
Cost of revenues:
Fuel	95.6	98.6
Purchased power	84.9	117.8
Total cost of revenues	180.5	216.4
Gross margin	219.1	233.4
Operating expenses:
Operation and maintenance	99.2	91.4
Depreciation and amortization	34.7	33.1
General taxes	20.2	19.6
Total operating expenses	154.1	144.1
Operating income	65.0	89.3
Other income / (expense), net:
Investment income	0.1	0.6
Interest expense	(9.6)	(9.7)
Other expense	(0.1)	(0.5)
Total other income / (expense), net	(9.6)	(9.6)
Earnings before income tax	55.4	79.7
Income tax expense	17.3	27.0
Net income	38.1	52.7
Dividends on preferred stock	0.2	0.2
Earnings on common stock	37.9	52.5
Successor [Member]
Revenues	434.0
Cost of revenues:
Fuel	97.4
Purchased power	94.8
Amortization of intangibles	27.8
Total cost of revenues	220.0
Gross margin	214.0
Operating expenses:
Operation and maintenance	101.7
Depreciation and amortization	31.4
General taxes	21.7
Total operating expenses	154.8
Operating income	59.2
Other income / (expense), net:
Investment income	0.1
Interest expense	(29.6)
Charge for early redemption of debt
Other expense	(0.3)
Total other income / (expense), net	(29.8)
Earnings before income tax	29.4
Income tax expense	7.7
Net income	21.7
Predecessor [Member]
Revenues		480.6
Cost of revenues:
Fuel		99.7
Purchased power		120.8
Amortization of intangibles		0
Total cost of revenues		220.5
Gross margin		260.1
Operating expenses:
Operation and maintenance		99.3
Depreciation and amortization		35.1
General taxes		24.8
Total operating expenses		159.2
Operating income		100.9
Other income / (expense), net:
Investment income		0.1
Interest expense		(16.9)
Charge for early redemption of debt		(15.3)
Other expense		(0.5)
Total other income / (expense), net		(32.6)
Earnings before income tax		68.3
Income tax expense		24.8
Net income		$ 43.5
Average number of common shares outstanding (millions):
Basic		114.0
Diluted		114.5
Earnings per share of common stock:
Basic		$ 0.38
Diluted		$ 0.38
Dividends paid per share of common stock		$ 0.3325