Consolidated Statements of Results of Operations (USD $) In Millions, except Per Share data, unless otherwise specified	12 Months Ended			1 Months Ended	12 Months Ended	11 Months Ended	12 Months Ended
	Dec. 31, 2012 THE DAYTON POWER AND LIGHT COMPANY [Member]	Dec. 31, 2011 THE DAYTON POWER AND LIGHT COMPANY [Member]	Dec. 31, 2010 THE DAYTON POWER AND LIGHT COMPANY [Member]	Dec. 31, 2011 Successor [Member]	Dec. 31, 2012 Successor [Member]	Nov. 27, 2011 Predecessor [Member]	Dec. 31, 2010 Predecessor [Member]
Revenues	$ 1,531.8	$ 1,677.7	$ 1,738.8	$ 156.9	$ 1,668.4	$ 1,670.9	$ 1,831.4
Cost of revenues:
Fuel	354.9	380.6	371.9	35.8	361.9	355.8	383.9
Purchased power	309.5	401.6	383.5	36.7	342.1	404.6	387.4
Amortization of intangibles				11.6	95.1
Total cost of revenues	664.4	782.2	755.4	84.1	799.1	760.4	771.3
Gross margin	867.4	895.5	983.4	72.8	869.3	910.5	1,060.1
Operating expenses:
Operation and maintenance	385.9	364.8	330.1	47.5	406.4	377.8	340.6
Depreciation and amortization	141.3	134.9	130.7	11.6	125.4	129.4	139.4
General taxes	74.4	75.9	72.4	7.6	79.5	75.5	75.7
Goodwill Impairment					1,817.2
Fixed asset impairment	80.8
Total operating expenses	682.4	575.6	533.2	66.7	2,428.5	582.7	555.7
Operating income	185.0	319.9	450.2	6.1	(1,559.2)	327.8	504.4
Other income / (expense), net:
Investment income	2.3	17.3	1.7	0.1	2.5	0.4	1.8
Interest expense	(39.1)	(38.2)	(37.1)	(11.5)	(122.9)	(58.7)	(70.6)
Charge for early redemption of debt						(15.3)
Other expense	(1.9)	(1.6)	(1.9)	(0.3)	(2.5)	(1.7)	(2.3)
Total other income / (expense), net	(38.7)	(22.5)	(37.3)	(11.7)	(122.9)	(75.3)	(71.1)
Earnings before income tax	146.3	297.4	412.9	(5.6)	(1,682.1)	252.5	433.3
Income tax expense	55.1	104.2	135.2	0.6	47.7	102.0	143.0
Net income	91.2	193.2	277.7	(6.2)	(1,729.8)	150.5	290.3
Dividends on preferred stock	0.9	0.9	0.9
Earnings on common stock	$ 90.3	$ 192.3	$ 276.8
Average number of common shares outstanding (millions):
Basic						114.5	115.6
Diluted						115.1	116.1
Earnings per share of common stock:
Basic						$ 1.31	$ 2.51
Diluted						$ 1.31	$ 2.50
Dividends paid per share of common stock						$ 1.54	$ 1.21