Income Taxes (Components of Income Tax Expense) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended				1 Months Ended		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 DP&L [Member]	Dec. 31, 2011 Successor [Member]		Dec. 31, 2013 Successor [Member]		Dec. 31, 2012 Successor [Member]		Dec. 31, 2011 Successor [Member] Parent Company [Member]	Dec. 31, 2013 Successor [Member] Parent Company [Member]	Dec. 31, 2012 Successor [Member] Parent Company [Member]	Nov. 27, 2011 Predecessor [Member]		Nov. 27, 2011 Predecessor [Member] Parent Company [Member]
Federal income tax		$ 35.5	$ 50.9	$ 103.8	$ (2.0)	[1]	$ (69.9)	[1]	$ (588.7)	[1]				$ 88.4	[1]
State income taxes, net of federal effect		0.3	(2.0)	1.4	0.1		1.7		3.5					3.8
Depreciation of AFUDC - Equity		(2.5)	3.0	(3.2)	(0.3)		(3.2)		(2.4)					(2.9)
Investment tax credit amortized		(2.5)	(2.5)	(2.5)	(0.2)		(0.5)		(0.3)					(2.3)
Section 199 - domestic production deduction		(4.1)	(2.5)	(4.9)			(4.1)		(2.1)					(3.6)
Non-deductible merger costs			0.6	3.6	0.1									6.0
Non-deductible merger-related compensation					3.5				0.6
Non-deductible goodwill impairment							107.2		636.0
Accrual (settlement) for open tax years	(8.8)				0.1		(8.8)		(0.1)					0.1
ESOP				13.6
Income Tax Rate Reconciliation, Deductions, Employee Stock Ownership Plan Dividends				13.6
Compensation on benefits				(5.3)										13.8
Income not subject to tax					(0.6)
Other, net		0.7	7.6	(2.3)	(0.1)	[2]	(0.1)	[2]	1.2	[2]				(1.3)	[2]
Total tax expense		18.6	55.1	104.2	0.6		22.3		47.7		0.6	22.3	47.7	102.0		102.0
Federal - Current		38.6	52.1	54.9	0.4		1.8		48.6					53.2
State and Local - Current		(0.1)	1.0	0.9	0.4		0.7		1.2					0.9
Total Current		38.5	53.1	55.8	0.8		2.5		49.8					54.1
Federal - Deferred		(20.4)	4.7	47.1	(0.2)		18.1		(4.9)					43.2
State and Local - Deferred		0.5	(2.7)	1.3			1.7		2.8					4.7
Deferred income taxes					0.1		24.0		(4.2)					65.5
Total Deferred		$ (19.9)	$ 2.0	$ 48.4	$ (0.2)		$ 19.8		$ (2.1)					$ 47.9

[1] Components of Deferred Tax Assets and Liabilities (Successor)Years ended December 31,$ in millions20132012Net non-current Assets / (Liabilities)Depreciation / property basis$ (531.5)$ (517.0)Income taxes recoverable (11.4) (12.3)Regulatory assets (15.6) (20.6)Investment tax credit 1.0 1.2Intangibles (3.9) (2.4)Compensation and employee benefits (2.0) 2.2Long-term debt (1.7) (2.0)Other (c) 0.8 16.0Net non-current liabilities$ (564.3)$ (534.9)Net current Assets / (Liabilities) (d)Other$ (2.6)$ 4.7Net current assets / (liabilities)$ (2.6)$ 4.7(a)The statutory tax rate of 35% was applied to pre-tax earnings.

[2] (b)Includes expense of $0.0 million, $1.2 million and benefits of $0.0 million and $2.3 million in the years ended December 31, 2013 and 2012, the period November 28, 2011 through December 31, 2011 and the period January 1, 2011 through November 27, 2011, respectively, of income tax related to adjustments from prior years.