Consolidated Statements of Shareholders' Equity - USD ($) $ in Millions	Total	Common Stock [Member]	Other Paid-In Capital [Member]	Accumulated Other Comprehensive Income/(Loss) [Member]	Retained Earnings [Member]	THE DAYTON POWER AND LIGHT COMPANY [Member]	THE DAYTON POWER AND LIGHT COMPANY [Member] Common Stock [Member]	THE DAYTON POWER AND LIGHT COMPANY [Member] Other Paid-In Capital [Member]	THE DAYTON POWER AND LIGHT COMPANY [Member] Accumulated Other Comprehensive Income/(Loss) [Member]	THE DAYTON POWER AND LIGHT COMPANY [Member] Retained Earnings [Member]
Balance at Dec. 31, 2013	$ 239.5	$ 0.0	$ 2,237.0	$ 24.6	$ (2,022.1)	$ 1,204.0	$ 0.4	$ 803.5	$ (26.7)	$ 426.8
Balance (in shares) at Dec. 31, 2013		1					41,172,173
Net comprehensive income/ (loss)	(91.7)			(17.1)	(74.6)	99.4			(15.6)	115.0
Common stock dividends						(159.0)				(159.0)
Preferred stock dividends						(0.9)				(0.9)
Other	0.4		0.4		0.0	(0.1)				(0.1)
Balance at Dec. 31, 2014	148.2	$ 0.0	2,237.4	7.5	(2,096.7)	1,143.4	$ 0.4	803.5	(42.3)	381.8
Balance (in shares) at Dec. 31, 2014		1					41,172,173
Net comprehensive income/ (loss)	(229.1)			9.9	(239.0)	120.0			13.6	106.4
Common stock dividends						(50.0)				(50.0)
Preferred stock dividends						(0.9)				(0.9)
Other	0.3		0.3		0.0	0.2		0.2
Balance at Dec. 31, 2015	(80.6)	$ 0.0	2,237.7	17.4	(2,335.7)	1,212.7	$ 0.4	803.7	(28.7)	437.3
Balance (in shares) at Dec. 31, 2015		1					41,172,173
Preferred Stock Redemption Premium	5.1
Net comprehensive income/ (loss)	(502.3)			(17.1)	(485.2)	(786.5)			(13.8)	(772.7)
Common stock dividends						(70.0)				(70.0)
Preferred stock dividends						(0.7)				(0.7)
Other	(4.7)		(4.7)		0.0	6.8		7.0		(0.2)
Balance at Dec. 31, 2016	$ (587.6)	$ 0.0	$ 2,233.0	$ 0.3	$ (2,820.9)	$ 362.3	$ 0.4	$ 810.7	$ (42.5)	$ (406.3)
Balance (in shares) at Dec. 31, 2016		1