Summary of Significant Accounting Policies (Narrative) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2014 sqmi employee	Dec. 31, 2013 sqmi	Dec. 31, 2012
Service Area Square Miles	6,000	6,000
Approximate number of retail customers	516,000	516,000
DPLER Customers That Are DPL Electric Distribution Customers	131,000
Approximate number of DPLER customers	260,000
Entity number of employees	1,182
Number of coal fired power plants	5	5
Employees under a collective bargaining agreement which expires in October-2011	61.00%
Capitalized interest for unregulated generation propety	$ 1.5	$ 1.5	$ 4.0
Straight-line depreciation average annual composite basis	5.30%	5.80%	4.80%
Asset Removal Costs	119.3	115.0	112.1
Additional Insurance Claims Cost	15.6	18.8
Investment in trust	0.3	0.4
Notes payable to trust	14.9
Electric Generation supplied to customers	100.00
Electric Generation through competitive bid	100.00
DP&L [Member]
Service Area Square Miles	6,000
Approximate number of retail customers	516,000
Entity number of employees	1,130
Number of coal fired power plants	5
Employees under a collective bargaining agreement which expires in October-2011	64.00%
Capitalized interest for unregulated generation propety	1.5	1.5	4.0
Straight-line depreciation average annual composite basis	2.80%	4.40%	4.20%
Asset Removal Costs	119.3	115.0	112.1
Additional Insurance Claims Cost	$ 15.6	$ 18.8
Electric Generation supplied to customers	100.00
Electric Generation through competitive bid	100.00