Share-Based Compensation (Narrative) (Details) (USD $) In Millions, except Share data, unless otherwise specified	11 Months Ended		12 Months Ended
	Nov. 27, 2011		Dec. 31, 2011	Dec. 31, 2010
Acquisition cost per share			$ 30.00
Total share-based compensation, net of tax	$ 6.6			$ 3.1
Share-based compensation included in Operation and maintenance expense	10.1			4.7
Shares issued under equity and performance incentive plan (EPIP)	4,500,000
Share-based Compensation Arrangement by Share-based Payment Award Accelerated Compensation Cost	5.5
Share-based Compensation Arrangement by Share-based Payment Award Accelerated Compensation CostNetofTax	3.6
DP&L [Member]
Total share-based compensation, net of tax	6.6			3.1
Share-based compensation included in Operation and maintenance expense	10.1			4.7
Shares issued under equity and performance incentive plan (EPIP)	4,500,000
Share-based Compensation Arrangement by Share-based Payment Award Accelerated Compensation Cost	5.5
Share-based Compensation Arrangement by Share-based Payment Award Accelerated Compensation CostNetofTax	3.6
Restricted Shares [Member]
Acquisition cost per share	$ 30.00
Share-based compensation included in Operation and maintenance expense	5.3			1.7
Restricted Shares [Member] | DP&L [Member]
Acquisition cost per share	$ 30.00
Share-based compensation included in Operation and maintenance expense	5.3			1.7
Director RSU's [Member]
Acquisition cost per share	$ 30.00
Share-based compensation included in Operation and maintenance expense	0.6			0.4
Director RSU's [Member] | DP&L [Member]
Acquisition cost per share	$ 30.00
Share-based compensation included in Operation and maintenance expense	0.6	[1]		0.4	[1]
Management Performance Shares [Member]
Acquisition cost per share	$ 30.00
Share-based compensation included in Operation and maintenance expense	1.8			0.5
Management Performance Shares [Member] | DP&L [Member]
Acquisition cost per share	$ 30.00
Share-based compensation included in Operation and maintenance expense	1.8			0.5
Performance Shares [Member]
Acquisition cost per share	$ 30.00
Share-based compensation included in Operation and maintenance expense	2.4			2.1
Performance Shares [Member] | DP&L [Member]
Acquisition cost per share	$ 30.00
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.