Share-Based Compensation (Summarized Share-Based Compensation Expense) (Details) (USD $) In Millions, unless otherwise specified	11 Months Ended		12 Months Ended
	Nov. 27, 2011		Dec. 31, 2010
Share-based compensation included in Operation and maintenance expense	$ 10.1		$ 4.7
Income tax expense / (benefit)	(3.5)		(1.6)
Total share-based compensation, net of tax	6.6		3.1
DP&L [Member]
Share-based compensation included in Operation and maintenance expense	10.1		4.7
Income tax expense / (benefit)	(3.5)		(1.6)
Total share-based compensation, net of tax	6.6		3.1
Restricted Shares [Member]
Share-based compensation included in Operation and maintenance expense	5.3		1.7
Restricted Shares [Member] | DP&L [Member]
Share-based compensation included in Operation and maintenance expense	5.3		1.7
Director RSU's [Member]
Share-based compensation included in Operation and maintenance expense	0.6		0.4
Director RSU's [Member] | DP&L [Member]
Share-based compensation included in Operation and maintenance expense	0.6	[1]	0.4	[1]
Management Performance Shares [Member]
Share-based compensation included in Operation and maintenance expense	1.8		0.5
Management Performance Shares [Member] | DP&L [Member]
Share-based compensation included in Operation and maintenance expense	1.8		0.5
Performance Shares [Member]
Share-based compensation included in Operation and maintenance expense	2.4		2.1
Performance Shares [Member] | DP&L [Member]
Share-based compensation included in Operation and maintenance expense	$ 2.4		$ 2.1

[1] (a) Includes an amount associated with compensation awarded to DPL’s Board of Directors which is immaterial in total.