Derivative Instruments and Hedging Activities (Classification within the Condensed Consolidated Statements of Results of Operations or Balance Sheets of the Gains and Losses) (Details) (USD $) In Millions, unless otherwise specified	1 Months Ended	11 Months Ended	12 Months Ended		1 Months Ended	11 Months Ended	12 Months Ended	1 Months Ended	11 Months Ended	12 Months Ended		1 Months Ended	11 Months Ended	12 Months Ended		1 Months Ended	11 Months Ended	12 Months Ended																1 Months Ended	11 Months Ended	12 Months Ended	1 Months Ended	11 Months Ended	12 Months Ended							1 Months Ended	11 Months Ended	12 Months Ended		1 Months Ended	11 Months Ended	12 Months Ended	1 Months Ended	11 Months Ended	12 Months Ended										11 Months Ended	12 Months Ended	11 Months Ended	12 Months Ended					1 Months Ended	11 Months Ended	12 Months Ended		1 Months Ended	11 Months Ended	12 Months Ended		1 Months Ended	11 Months Ended	12 Months Ended
	Dec. 31, 2011	Nov. 27, 2011	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011 NYMEX Coal Contract [Member]	Nov. 27, 2011 NYMEX Coal Contract [Member]	Dec. 31, 2012 NYMEX Coal Contract [Member]	Dec. 31, 2011 Commodity Contract - FTR [Member]	Nov. 27, 2011 Commodity Contract - FTR [Member]	Dec. 31, 2013 Commodity Contract - FTR [Member]	Dec. 31, 2012 Commodity Contract - FTR [Member]	Dec. 31, 2011 Commodity Contract - Heating Oil [Member]	Nov. 27, 2011 Commodity Contract - Heating Oil [Member]	Dec. 31, 2013 Commodity Contract - Heating Oil [Member]	Dec. 31, 2012 Commodity Contract - Heating Oil [Member]	Dec. 31, 2011 Forward Contract Power [Member]	Nov. 27, 2011 Forward Contract Power [Member]	Dec. 31, 2013 Forward Contract Power [Member]	Dec. 31, 2012 Forward Contract Power [Member]	Dec. 31, 2013 DP&L [Member]	Dec. 31, 2012 DP&L [Member]	Dec. 31, 2011 DP&L [Member]	Dec. 31, 2012 DP&L [Member] NYMEX Coal Contract [Member]	Dec. 31, 2011 DP&L [Member] NYMEX Coal Contract [Member]	Dec. 31, 2013 DP&L [Member] Commodity Contract - FTR [Member]	Dec. 31, 2012 DP&L [Member] Commodity Contract - FTR [Member]	Dec. 31, 2011 DP&L [Member] Commodity Contract - FTR [Member]	Dec. 31, 2013 DP&L [Member] Commodity Contract - Heating Oil [Member]	Dec. 31, 2012 DP&L [Member] Commodity Contract - Heating Oil [Member]	Dec. 31, 2011 DP&L [Member] Commodity Contract - Heating Oil [Member]	Dec. 31, 2013 DP&L [Member] Forward Contract Power [Member]	Dec. 31, 2012 DP&L [Member] Forward Contract Power [Member]	Dec. 31, 2011 DP&L [Member] Forward Contract Power [Member]	Dec. 31, 2011 Revenue [Member]	Nov. 27, 2011 Revenue [Member]	Dec. 31, 2012 Revenue [Member]	Dec. 31, 2011 Revenue [Member] Forward Contract Power [Member]	Nov. 27, 2011 Revenue [Member] Forward Contract Power [Member]	Dec. 31, 2012 Revenue [Member] Forward Contract Power [Member]	Dec. 31, 2013 Revenue [Member] DP&L [Member]	Dec. 31, 2012 Revenue [Member] DP&L [Member]	Dec. 31, 2011 Revenue [Member] DP&L [Member]	Dec. 31, 2013 Revenue [Member] DP&L [Member] Forward Contract Power [Member]	Dec. 31, 2012 Revenue [Member] DP&L [Member] Forward Contract Power [Member]	Dec. 31, 2011 Revenue [Member] DP&L [Member] Forward Contract Power [Member]	Dec. 31, 2011 Fuel [Member]	Nov. 27, 2011 Fuel [Member]	Dec. 31, 2013 Fuel [Member]	Dec. 31, 2012 Fuel [Member]	Dec. 31, 2011 Fuel [Member] NYMEX Coal Contract [Member]	Nov. 27, 2011 Fuel [Member] NYMEX Coal Contract [Member]	Dec. 31, 2012 Fuel [Member] NYMEX Coal Contract [Member]	Dec. 31, 2011 Fuel [Member] Commodity Contract - Heating Oil [Member]	Nov. 27, 2011 Fuel [Member] Commodity Contract - Heating Oil [Member]	Dec. 31, 2013 Fuel [Member] Commodity Contract - Heating Oil [Member]	Dec. 31, 2012 Fuel [Member] Commodity Contract - Heating Oil [Member]	Dec. 31, 2013 Fuel [Member] DP&L [Member]	Dec. 31, 2012 Fuel [Member] DP&L [Member]	Dec. 31, 2011 Fuel [Member] DP&L [Member]	Dec. 31, 2012 Fuel [Member] DP&L [Member] NYMEX Coal Contract [Member]	Dec. 31, 2011 Fuel [Member] DP&L [Member] NYMEX Coal Contract [Member]	Dec. 31, 2013 Fuel [Member] DP&L [Member] Commodity Contract - Heating Oil [Member]	Dec. 31, 2012 Fuel [Member] DP&L [Member] Commodity Contract - Heating Oil [Member]	Dec. 31, 2011 Fuel [Member] DP&L [Member] Commodity Contract - Heating Oil [Member]	Nov. 27, 2011 O&M [Member]	Dec. 31, 2012 O&M [Member]	Nov. 27, 2011 O&M [Member] Commodity Contract - Heating Oil [Member]	Dec. 31, 2012 O&M [Member] Commodity Contract - Heating Oil [Member]	Dec. 31, 2012 O&M [Member] DP&L [Member]	Dec. 31, 2011 O&M [Member] DP&L [Member]	Dec. 31, 2012 O&M [Member] DP&L [Member] Commodity Contract - Heating Oil [Member]	Dec. 31, 2011 O&M [Member] DP&L [Member] Commodity Contract - Heating Oil [Member]	Dec. 31, 2011 Purchased Power [Member]	Nov. 27, 2011 Purchased Power [Member]	Dec. 31, 2013 Purchased Power [Member]	Dec. 31, 2012 Purchased Power [Member]	Dec. 31, 2011 Purchased Power [Member] Commodity Contract - FTR [Member]	Nov. 27, 2011 Purchased Power [Member] Commodity Contract - FTR [Member]	Dec. 31, 2013 Purchased Power [Member] Commodity Contract - FTR [Member]	Dec. 31, 2012 Purchased Power [Member] Commodity Contract - FTR [Member]	Dec. 31, 2011 Purchased Power [Member] Forward Contract Power [Member]	Nov. 27, 2011 Purchased Power [Member] Forward Contract Power [Member]	Dec. 31, 2013 Purchased Power [Member] Forward Contract Power [Member]	Dec. 31, 2012 Purchased Power [Member] Forward Contract Power [Member]	Dec. 31, 2013 Purchased Power [Member] DP&L [Member]	Dec. 31, 2012 Purchased Power [Member] DP&L [Member]	Dec. 31, 2011 Purchased Power [Member] DP&L [Member]	Dec. 31, 2013 Purchased Power [Member] DP&L [Member] Commodity Contract - FTR [Member]	Dec. 31, 2012 Purchased Power [Member] DP&L [Member] Commodity Contract - FTR [Member]	Dec. 31, 2011 Purchased Power [Member] DP&L [Member] Commodity Contract - FTR [Member]	Dec. 31, 2013 Purchased Power [Member] DP&L [Member] Forward Contract Power [Member]	Dec. 31, 2012 Purchased Power [Member] DP&L [Member] Forward Contract Power [Member]	Dec. 31, 2011 Purchased Power [Member] DP&L [Member] Forward Contract Power [Member]
Change in unrealized gain / (loss)	$ (2.7)	$ (49.5)	$ 0.9	$ 17.0	$ (1.4)	$ (50.7)	$ 14.5		$ (0.2)	$ 0.3	$ (0.2)	$ (0.5)	$ 0.6		$ (1.6)	$ (0.8)	$ 0.8	$ 0.6	$ 4.3	$ (0.9)	$ 15.7	$ (51.8)	$ 14.5	$ (52.1)	$ 0.3	$ (0.2)	$ (0.1)		$ (1.6)	$ 0.1	$ (1.2)	$ 3.0	$ 0.3
Gain (Loss) on Derivative Instruments, Net, Pretax	(1.9)	7.6	2.4	(32.1)	(1.2)	8.7	(29.5)	0.1	(0.6)	1.2	0.5	0.1	2.2	0.1	1.9	(0.9)	(2.7)	1.1	(5.0)	2.9	(22.2)	7.8	(29.5)	7.5	1.2	0.5	(0.6)	0.1	1.9	2.3	1.6	4.9	(1.4)
Partner's share of gain (loss)	(0.3)	(25.9)		4.2	(0.3)	(25.9)	4.2														4.2	(26.1)	4.2	(26.1)
Regulatory (asset)/liability	(0.2)	(6.9)		0.4	(0.1)	(7.0)	1.0					(0.1)	0.1		(0.6)						0.4	(7.1)	1.0	(7.1)					(0.6)
Derivative, Gain (Loss) on Derivative, Net	$ (4.6)	$ (41.9)	$ 3.3	$ (15.1)	$ (2.6)	$ (42.0)	$ (15.0)	$ 0.1	$ (0.8)	$ 1.5	$ 0.3	$ (0.4)	$ 2.8	$ 0.1	$ 0.3	$ (1.7)	$ (1.9)	$ 1.7	$ (0.7)	$ 2.0	$ (6.5)	$ (44.0)	$ (15.0)	$ (44.6)	$ 1.5	$ 0.3	$ (0.7)	$ 0.1	$ 0.3	$ 2.4	$ 0.4	$ 7.9	$ (1.1)	$ 0.6	$ (3.8)	$ (5.1)	$ 0.6	$ (3.8)	$ (5.1)	$ 0.2	$ 2.7	$ 2.5	$ 0.2	$ 2.7	$ 2.5	$ (2.5)	$ (6.6)	$ 0.1	$ (19.5)	$ (2.2)	$ (9.1)	$ (20.2)	$ (0.3)	$ 2.5	$ 0.1	$ 0.7	$ 0.1	$ (19.5)	$ (9.2)	$ (20.2)	$ (11.4)	$ 0.1	$ 0.7	$ 2.2	$ 0.2	$ 0.2	$ 0.2	$ 0.2	$ 0.2	$ 0.2	$ 0.2	$ 0.2	$ (2.2)	$ 1.1	$ 3.2	$ 4.7	$ 0.1	$ (0.8)	$ 1.5	$ 0.3	$ (2.3)	$ 1.9	$ 1.7	$ 4.4	$ 1.7	$ 5.5	$ (4.3)	$ 1.5	$ 0.3	$ (0.7)	$ 0.2	$ 5.2	$ (3.6)