Overview and Summary of Significant Accounting Policies (Narrative) (Details) (USD $) In Millions, unless otherwise specified	1 Months Ended	11 Months Ended	12 Months Ended
	Dec. 31, 2011	Nov. 27, 2011	Dec. 31, 2012 sqmi employee	Dec. 31, 2011	Dec. 31, 2010
Service Area Square Miles			6,000
Service Area By County			24
Approximate number of retail customers			513,000
DPLER Customers That Are DPL Electric Distribution Customers			74,000
Approximate number of DPLER customers			198,000
Entity number of employees			1,486
Number of coal fired power plants			8
Employees under a collective bargaining agreement which expires in October-2011			52.00%
Deferred SECA revenue	$ 17.8		$ 14.6	$ 17.8
SECA interest income			1.8
Capitalized interest for unregulated generation propety	0.5	3.9	4.0		3.4
Reduction in depreciation expense gross of tax			9.6	4.8
Reduction in depreciation expense net of tax			6.2	3.1
Straight-line depreciation average annual composite basis			4.80%	5.80%	2.60%
Asset Removal Costs	112.4		112.1	112.4
Insurance and claims costs	14.2		11.5	14.2
Additional Insurance Claims Cost	18.9		17.7	18.9
Investment in trust			0.5
Notes payable to trust	19.5		19.6	19.5
DP&L [Member]
Service Area Square Miles			6,000
Service Area By County			24
Approximate number of retail customers			513,000
Entity number of employees			1,428
Number of coal fired power plants			8
Employees under a collective bargaining agreement which expires in October-2011			52.00%
Deferred SECA revenue	17.8		14.6	17.8
SECA interest income			1.8
Capitalized interest for unregulated generation propety			4.0	4.4	3.4
Reduction of future depreciation due to asset impairment			7.1
Reduction of current depreciation due to asset impairment			1.8
Reduction in depreciation expense gross of tax			6.8	3.4
Reduction in depreciation expense net of tax			4.4	2.2
Straight-line depreciation average annual composite basis			4.20%	2.50%	2.60%
Asset Removal Costs	$ 112.4		$ 112.1	$ 112.4	$ 107.9