Debt Obligations (Long-term Debt Maturities) (Details) (USD $) In Millions, unless otherwise specified	Sep. 30, 2014
Due within one year	$ 110.1
Due within two years	385.1
Due within three years	470.1
Due within four years	70.1
Due within five years	0.1
Thereafter	1,232.7
Total Maturities	2,268.2
Unamortized discounts and premiums, net	3.8
Total	2,264.4
DP&L [Member]
Due within one year	0.1
Due within two years	445.1
Due within three years	0.1
Due within four years	0.1
Due within five years	0.1
Thereafter	432.1
Total Maturities	877.6
Unamortized discounts and premiums, net	(0.5)
Total	$ 877.1