Consolidated Statements of Shareholders' Equity (USD $) In Millions, except Share data	THE DAYTON POWER AND LIGHT COMPANY [Member] Common Stock [Member] USD ($)	THE DAYTON POWER AND LIGHT COMPANY [Member] Other Paid-In Capital [Member] USD ($)	THE DAYTON POWER AND LIGHT COMPANY [Member] Accumulated Other Comprehensive Income/(Loss) [Member] USD ($)	THE DAYTON POWER AND LIGHT COMPANY [Member] Retained Earnings [Member] USD ($)	THE DAYTON POWER AND LIGHT COMPANY [Member] USD ($)	Common Stock [Member] Successor [Member]	Common Stock [Member] Predecessor [Member] USD ($)	Warrant [Member] Predecessor [Member] USD ($)	Common Stock Held By Employee Plans [Member] Predecessor [Member] USD ($)	Other Paid-In Capital [Member] Successor [Member] USD ($)	Accumulated Other Comprehensive Income/(Loss) [Member] Successor [Member] USD ($)	Accumulated Other Comprehensive Income/(Loss) [Member] Predecessor [Member] USD ($)	Retained Earnings [Member] Successor [Member] USD ($)		Retained Earnings [Member] Predecessor [Member] USD ($)	Successor [Member] USD ($)		Predecessor [Member] USD ($)	Total USD ($)
Balance at Dec. 31, 2009	$ 0.4	$ 781.6	$ (19.7)	$ 640.3	$ 1,402.6		$ 1.2	$ 2.9	$ (19.3)			$ (29.0)			$ 1,144.1			$ 1,099.9
Balance (in shares) at Dec. 31, 2009	41,172,173						118,966,767
Net income					277.7													290.3
Total comprehensive income / (Loss)			(0.5)	277.7	277.2							10.1			290.3			300.4
Common stock dividends				(300.0)	(300.0)										(139.7)			(139.7)
Preferred stock dividends				(0.9)	(0.9)
Repurchase of warrants								(0.2)										(0.2)
Exercise of warrants (in shares)							18,288
Treasury stock purchased															(56.4)			(56.4)
Treasury stock purchased (in shares)							(2,182,751)
Treasury stock reissued															2.4			2.4
Treasury stock reissued (in shares)							122,540
Tax effects to equity		0.2			0.2										0.2			0.2
Employee / Director stock plans		0.4			0.4				6.8						5.1			11.9
Other		0.2		(0.2)
Balance at Dec. 31, 2010	0.4	782.4	(20.2)	616.9	1,379.5		1.2	2.7	(12.5)			(18.9)			1,246.0			1,218.5
Balance (in shares) at Dec. 31, 2010	41,172,173						116,924,844
Net income																		150.5
Total comprehensive income / (Loss)												(55.3)			150.5			95.2
Common stock dividends															(176.0)			(176.0)
Repurchase of warrants								(1.1)										(1.1)
Treasury stock reissued															18.2			18.2
Treasury stock reissued (in shares)							805,150
Tax effects to equity															1.4			1.4
Employee / Director stock plans									12.7						1.8			14.5
Other												(0.1)			(0.1)			(0.2)
Balance at Nov. 27, 2011							1.2	1.6	0.2			(74.3)			1,241.8			1,170.5
Balance (in shares) at Nov. 27, 2011							117,729,994
Balance at Dec. 31, 2010	0.4	782.4	(20.2)	616.9	1,379.5
Balance (in shares) at Dec. 31, 2010	41,172,173
Net income					193.2
Total comprehensive income / (Loss)			(14.4)	193.2	178.8
Common stock dividends				(220.0)	(220.0)
Preferred stock dividends				(0.9)	(0.9)
Contribution from Parent		20.0			20.0
Tax effects to equity		1.4			1.4
Employee / Director stock plans		(5.4)			(5.4)
Other		4.7		(0.2)	4.5
Balance at Dec. 31, 2011	0.4	803.1	(34.6)	589.0	1,357.9														2,230.7
Balance (in shares) at Dec. 31, 2011	41,172,173					1
Balance at Nov. 27, 2011
Capitalization at merger										2,235.6						2,235.6
Net income																(6.2)
Total comprehensive income / (Loss)											(0.4)		(6.2)			(6.6)
Contribution from Parent										1.7						1.7
Balance at Dec. 31, 2011	0.4	803.1	(34.6)	589.0	1,357.9					2,237.3	(0.4)		(6.2)			2,230.7			2,230.7
Balance (in shares) at Dec. 31, 2011	41,172,173					1
Net income					91.2											(1,729.8)
Total comprehensive income / (Loss)			(4.0)	91.2	87.2						(3.5)		(1,729.8)			(1,733.3)
Common stock dividends				(145.0)	(145.0)								(70.0)	[1]		(70.0)	[1]
Preferred stock dividends				(0.9)	(0.9)
Other		0.1		(0.2)	(0.1)					(0.6)						(0.6)
Balance at Dec. 31, 2012	$ 0.4	$ 803.2	$ (38.6)	$ 534.1	$ 1,299.1					$ 2,236.7	$ (3.9)		$ (1,806.0)			$ 426.8			$ 426.8
Balance (in shares) at Dec. 31, 2012	41,172,173					1

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