Goodwill Impairment (Narrative) (Details) (USD $) In Millions, unless otherwise specified	9 Months Ended	12 Months Ended
	Sep. 30, 2012	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Goodwill Allocated to DP&L Reporting Unit		$ 2,400.0
Goodwill Impairment	1,850.0	306.3	1,817.2
Goodwill		452.8	759.1	2,576.3
Effective Income Tax Rate, Continuing Operations		(11.20%)	(2.80%)
DP&L [Member]
Goodwill Impairment		(306.3)	(1,817.2)
Goodwill		$ 317.0	$ 623.3	$ 2,440.5