Overview and Summary of Significant Accounting Policies (Changes in the Liability for Transmission and Distribution Asset Removal Costs) (Details) (USD $) In Millions, unless otherwise specified			12 Months Ended		1 Months Ended	12 Months Ended	11 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2012 DP&L [Member]	Dec. 31, 2011 DP&L [Member]	Dec. 31, 2011 Successor [Member]	Dec. 31, 2012 Successor [Member]	Nov. 27, 2011 Predecessor [Member]
Balance at January 1	$ 112.1	$ 112.4	$ 112.4	$ 107.9	$ 112.2	$ 112.4	$ 107.9
Additions			10.1	9.4	0.8	10.1	8.6
Settlements			(10.4)	(4.9)	(0.6)	(10.4)	(4.3)
Balance at December 31	$ 112.1	$ 112.4	$ 112.1	$ 112.4	$ 112.4	$ 112.1	$ 112.2