Fair Value Measurements (Narrative) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012
Debt Maturities Maximum Period	2061
Debt Maturities Minimum Period	2016
Unrealized gains and immaterial unrealized losses in AOCI, before tax	$ 0.9	$ 0.7
Unrealized gains and immaterial unrealized losses in AOCI, after tax	0.6	0.5
Unrealized gains or losses are expected to be transferred to earnings in the next twelve months.	0.1
Unrealized gains or losses expected to be realized over next twelve months, net of tax	0.1
Percent of inputs to the fair value of derivative instruments from quoted market prices	95.00%
Gross additions to our existing landfill and asbestos AROs		0.1
Partial reduction to the ARO liability		0.1
Money market funds	0	130.0
Available-for-sale Securities, Gross Realized Gains (Losses), Sale Proceeds	2.1
AvailableForSaleSecuritiesGross Realized Gains Losses Sale Proceeds Net of Tax	1.4
DP&L [Member]
Unrealized gains and immaterial unrealized losses in AOCI, before tax	1.2	1.6
Unrealized gains and immaterial unrealized losses in AOCI, after tax	0.7	1.0
Unrealized gains or losses are expected to be transferred to earnings in the next twelve months.	0.1
Unrealized gains or losses expected to be realized over next twelve months, net of tax	0.1
Percent of inputs to the fair value of derivative instruments from quoted market prices	95.00%
Gross additions to our existing landfill and asbestos AROs		0.1
Partial reduction to the ARO liability		0.1
Available-for-sale Securities, Gross Realized Gains (Losses), Sale Proceeds	2.1	2.1
AvailableForSaleSecuritiesGross Realized Gains Losses Sale Proceeds Net of Tax	$ 1.4	$ 1.4