Condensed Consolidated Statements of Results of Operations (USD $) In Millions, except Per Share data	3 Months Ended		6 Months Ended
	Jun. 30, 2011	Jun. 30, 2010	Jun. 30, 2011	Jun. 30, 2010
Revenues	$ 444.9	$ 445.5	$ 939.6	$ 896.7
Cost of revenues:
Fuel	92.1	90.9	191.9	192.8
Purchased power	113.6	90.9	234.4	163.7
Total cost of revenues	205.7	181.8	426.3	356.5
Gross margin	239.2	263.7	513.3	540.2
Operating expenses:
Operation and maintenance	106.8	87.5	206.2	168.1
Depreciation and amortization	35.1	35.7	70.2	73.1
General taxes	31.5	31.2	70.3	63.7
Total operating expenses	173.4	154.4	346.7	304.9
Operating income	65.8	109.3	166.6	235.3
Other income / (expense), net:
Investment income	0.1	0.2	0.2	0.3
Interest expense	(17.6)	(17.5)	(34.5)	(35.4)
Charge for early redemption of debt			(15.3)
Other expense	(0.3)	(0.5)	(0.7)	(1.3)
Total other income / (expense), net	(17.8)	(17.8)	(50.3)	(36.4)
Earnings before income tax	48.0	91.5	116.3	198.9
Income tax expense	16.3	30.1	41.1	66.5
Net income	31.7	61.4	75.2	132.4
Earnings on common stock	31.7	61.4	75.2	132.4
Average number of common shares outstanding (millions):
Basic	114.2	115.7	114.1	115.6
Diluted	114.9	116.2	114.7	116.2
Earnings per share of common stock:
Basic	$ 0.28	$ 0.53	$ 0.66	$ 1.15
Diluted	$ 0.28	$ 0.53	$ 0.66	$ 1.14
Dividends paid per share of common stock	$ 0.3325	$ 0.3025	$ 0.665	$ 0.605
THE DAYTON POWER AND LIGHT COMPANY [Member]
Revenues	408.6	423.9	872.4	861.9
Cost of revenues:
Fuel	89.1	88.5	187.7	189.1
Purchased power	104.4	90.3	222.2	162.9
Total cost of revenues	193.5	178.8	409.9	352.0
Gross margin	215.1	245.1	462.5	509.9
Operating expenses:
Operation and maintenance	95.1	85.4	186.5	164.7
Depreciation and amortization	33.4	33.2	66.5	68.0
General taxes	30.8	29.5	64.4	61.8
Total operating expenses	159.3	148.1	317.4	294.5
Operating income	55.8	97.0	145.1	215.4
Other income / (expense), net:
Investment income	0.5	0.4	1.1	0.9
Interest expense	(9.7)	(9.1)	(19.4)	(18.5)
Other expense	(0.3)	(0.5)	(0.8)	(1.1)
Total other income / (expense), net	(9.5)	(9.2)	(19.1)	(18.7)
Earnings before income tax	46.3	87.8	126.0	196.7
Income tax expense	15.5	28.4	42.5	65.2
Net income	30.8	59.4	83.5	131.5
Dividends on preferred stock	0.2	0.2	0.4	0.4
Earnings on common stock	$ 30.6	$ 59.2	$ 83.1	$ 131.1