Income Taxes (Reconciliation of Unrecognized Tax Benefits) (Details) (USD $) In Millions, unless otherwise specified		12 Months Ended		1 Months Ended	12 Months Ended		11 Months Ended
	Dec. 31, 2013	Dec. 31, 2013 DP&L [Member]	Dec. 31, 2012 DP&L [Member]	Dec. 31, 2011 Successor [Member]	Dec. 31, 2013 Successor [Member]	Dec. 31, 2012 Successor [Member]	Nov. 27, 2011 Predecessor [Member]
Balance at beginning of year	$ 8.8	$ 18.3	$ 25.0	$ 24.9	$ 18.3	$ 25.0	$ 19.4
Tax positions taken during prior periods		(0.1)	(6.3)		(0.1)	(6.3)	2.0
Tax positions taken during current period		(2.5)	(0.4)	0.1	(2.5)	(0.4)
Settlement with taxing authorities, increase							3.5
Lapse of applicable statute of limitations		(6.9)			(6.9)
Balance at end of year	$ 8.8	$ 8.8	$ 18.3	$ 25.0	$ 8.8	$ 18.3	$ 24.9