Consolidated Statements of Cash Flows - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Cash flows from operating activities:
Net income (loss)		$ (485.2)	$ (239.0)	$ (74.6)
Adjustments to reconcile Net loss to Net cash from operating activities
Depreciation and amortization		132.3	138.8	139.8
Amortization of intangibles		0.0	0.0	1.2
Amortization of debt market value adjustments		0.1	(1.1)	0.3
Amortization of deferred financing costs		5.6	5.9	6.3
Unrealized loss (gain) on derivatives		(4.3)	5.8	3.0
Deferred income taxes		(306.2)	(17.1)	17.7
Charge for early redemption of debt		3.1	2.1	30.9
Goodwill impairment	[1]	0.0	317.0	135.8
Fixed-asset impairment (Note 15)		859.0	0.0	11.5
Loss / (Gain) on asset disposal		(49.2)	0.4	(3.9)
Changes in certain assets and liabilities:
Accounts receivable		24.2	43.4	0.5
Inventories		32.0	(9.0)	(24.9)
Prepaid taxes		0.2	(1.3)	(0.9)
Taxes applicable to subsequent years		0.2	(3.4)	(7.1)
Deferred regulatory costs, net		4.1	21.8	5.4
Accounts payable		16.5	(5.1)	32.1
Accrued taxes payable		45.1	43.8	20.7
Accrued interest payable		(3.7)	(5.7)	(1.3)
Other current and deferred liabilities		(4.0)	(10.4)	(40.6)
Pension, retiree and other benefits		8.6	(0.7)	19.1
Unamortized investment tax credit		(0.4)	(0.5)	(0.5)
Insurance and claims costs		(0.5)	(0.5)	(0.2)
Other		(10.4)	23.3	(26.2)
Net cash provided by operating activities		267.1	308.5	244.1
Cash flows from investing activities:
Capital expenditures		(148.5)	(137.2)	(118.1)
Proceeds from sale of property		75.5	1.3	10.7
Insurance proceeds		6.3	0.0	0.3
Purchase of renewable energy credits		(0.4)	(0.8)	(3.5)
Increase in restricted cash		(11.8)	(0.4)	(3.3)
Other investing activities, net		1.1	0.4	1.3
Net cash used in investing activities		(77.8)	(136.7)	(112.6)
Cash flows from financing activities:
Deferred financing costs		(8.6)	(6.9)	(3.6)
Preferred Stock, Redemption Amount		(23.5)	0.0	0.0
Retirement of debt		(577.8)	(474.5)	(335.0)
Premium paid for early redemption of debt		0.0	0.0	(29.1)
Issuance of long-term debt		442.8	325.0	200.0
Borrowings from revolving credit facilities		15.0	80.0	190.0
Repayment of borrowings from revolving credit facilities		(15.0)	(80.0)	(190.0)
Net cash from financing activities		(167.1)	(156.4)	(167.7)
Cash and cash equivalents:
Net increase / (decrease) in cash		22.2	15.4	(36.2)
Balance at beginning of period		32.4	17.0
Cash and cash equivalents at end of period		54.6	32.4	17.0
Supplemental cash flow information:
Interest paid, net of amounts capitalized		103.8	111.6	117.3
Income taxes paid / (refunded), net		0.3	0.8	0.7
Non-cash financing and investing activities:
Accruals for capital expenditures		16.2	18.6	16.3
THE DAYTON POWER AND LIGHT COMPANY [Member]
Cash flows from operating activities:
Net income (loss)		(772.7)	106.4	115.0
Adjustments to reconcile Net loss to Net cash from operating activities
Depreciation and amortization		120.3	138.2	144.8
Amortization of deferred financing costs		2.9	2.9	3.1
Unrealized loss (gain) on derivatives		(4.2)	5.7	2.1
Deferred income taxes		(477.5)	(19.2)	7.5
Charge for early redemption of debt		0.5	5.0	0.0
Goodwill impairment			317.0
Fixed-asset impairment (Note 15)		1,353.5	0.0	0.0
Loss / (Gain) on asset disposal		0.0	0.4	(3.5)
Changes in certain assets and liabilities:
Accounts receivable		(9.7)	28.7	(7.1)
Inventories		32.2	(9.1)	(24.6)
Prepaid taxes		2.7	(1.3)	(1.1)
Taxes applicable to subsequent years		0.0	(3.7)	(6.9)
Deferred regulatory costs, net		4.1	21.8	5.4
Accounts payable		16.0	(5.8)	32.4
Accrued taxes payable		(10.5)	7.3	9.0
Accrued interest payable		(2.0)	(5.7)	0.1
Other current and deferred liabilities		(1.8)	(9.3)	(18.1)
Pension, retiree and other benefits		8.6	(0.7)	19.1
Unamortized investment tax credit		(2.3)	(2.4)	(2.5)
Other		5.2	2.5	(23.0)
Net cash provided by operating activities		264.8	256.7	251.7
Cash flows from investing activities:
Capital expenditures		(128.3)	(127.0)	(114.2)
Proceeds from sale of property		0.0	0.0	10.7
Insurance proceeds		6.1	5.2	0.9
Purchase of renewable energy credits		(0.4)	(0.8)	(3.5)
Increase in restricted cash		(11.9)	(0.3)	(3.7)
Other investing activities, net		1.1	0.4	1.3
Net cash used in investing activities		(133.4)	(122.5)	(108.5)
Cash flows from financing activities:
Dividends paid on preferred stock		(0.7)	(0.9)	(0.9)
Deferred financing costs		(8.5)	(3.9)	(0.7)
Preferred Stock, Redemption Amount		(23.5)	0.0	0.0
Retirement of debt		(445.3)	(314.4)	(0.1)
Issuance of long-term debt		442.8	200.0	0.0
Borrowings from revolving credit facilities		0.0	50.0	0.0
Repayment of borrowings from revolving credit facilities		0.0	(50.0)	0.0
Dividends paid on common stock to parent		(70.0)	(50.0)	(159.0)
Borrowings from related party		10.0	35.0	15.0
Repayment of borrowings from related party		(40.0)	0.0	(15.0)
Net cash from financing activities		(135.2)	(134.2)	(160.7)
Cash and cash equivalents:
Net increase / (decrease) in cash		(3.8)	0.0	(17.5)
Balance at beginning of period		5.4	5.4	22.9
Cash and cash equivalents at end of period		1.6	5.4	5.4
Supplemental cash flow information:
Interest paid, net of amounts capitalized		21.4	27.5	26.6
Income taxes paid / (refunded), net		0.3	0.8	0.7
Non-cash financing and investing activities:
Accruals for capital expenditures		14.8	16.9	16.3
Subsidiary of Common Parent [Member] | THE DAYTON POWER AND LIGHT COMPANY [Member]
Non-cash financing and investing activities:
Equity Settlement of Related Party Payable		$ 7.5	$ 0.0	$ 0.0

[1] Goodwill impairment of $135.8 million in 2014 has been reclassified to Discontinued operations in the Consolidated Statement of Operations.