Debt Obligations (Long-term Debt Maturities) (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2014
Due within one year	$ 20.1
Due within two years	615.1
Due within three years	40.1
Due within four years	60.1
Due within five years	200.1
Thereafter	1,227.7
Total Maturities	2,163.2
Unamortized discounts and premiums, net	3.5
Total	2,159.7
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